Merge branch 'develop' into features/cache-archives

61 files changed, 2867 insertions, 745 deletions

diff --git a/lib/spack/docs/basic_usage.rst b/lib/spack/docs/basic_usage.rst
index 6efed83621..50c48b802b 100644
--- a/lib/spack/docs/basic_usage.rst
+++ b/lib/spack/docs/basic_usage.rst
@@ -102,8 +102,8 @@ that the packages is installed:
    ==> adept-utils is already installed in /home/gamblin2/spack/opt/chaos_5_x86_64_ib/gcc@4.4.7/adept-utils@1.0-5adef8da.
    ==> Trying to fetch from https://github.com/hpc/mpileaks/releases/download/v1.0/mpileaks-1.0.tar.gz
    ######################################################################## 100.0%
-   ==> Staging archive: /home/gamblin2/spack/var/spack/stage/mpileaks@1.0%gcc@4.4.7=chaos_5_x86_64_ib-59f6ad23/mpileaks-1.0.tar.gz
-   ==> Created stage in /home/gamblin2/spack/var/spack/stage/mpileaks@1.0%gcc@4.4.7=chaos_5_x86_64_ib-59f6ad23.
+   ==> Staging archive: /home/gamblin2/spack/var/spack/stage/mpileaks@1.0%gcc@4.4.7 arch=chaos_5_x86_64_ib-59f6ad23/mpileaks-1.0.tar.gz
+   ==> Created stage in /home/gamblin2/spack/var/spack/stage/mpileaks@1.0%gcc@4.4.7 arch=chaos_5_x86_64_ib-59f6ad23.
    ==> No patches needed for mpileaks.
    ==> Building mpileaks.
 
@@ -132,10 +132,10 @@ sites, as installing a version that one user needs will not disrupt
 existing installations for other users.
 
 In addition to different versions, Spack can customize the compiler,
-compile-time options (variants), and platform (for cross compiles) of
-an installation.  Spack is unique in that it can also configure the
-*dependencies* a package is built with.  For example, two
-configurations of the same version of a package, one built with boost
+compile-time options (variants), compiler flags, and platform (for
+cross compiles) of an installation.  Spack is unique in that it can
+also configure the *dependencies* a package is built with.  For example,
+two configurations of the same version of a package, one built with boost
 1.39.0, and the other version built with version 1.43.0, can coexist.
 
 This can all be done on the command line using the *spec* syntax.
@@ -334,9 +334,15 @@ of libelf would look like this:
    -- chaos_5_x86_64_ib / gcc@4.4.7 --------------------------------
    libdwarf@20130729-d9b90962
 
+We can also search for packages that have a certain attribute. For example,
+``spack find -l libdwarf +debug`` will show only installations of libdwarf
+with the 'debug' compile-time option enabled, while ``spack find -l +debug``
+will find every installed package with a 'debug' compile-time option enabled.
+
 The full spec syntax is discussed in detail in :ref:`sec-specs`.
 
 
+
 Compiler configuration
 -----------------------------------
 
@@ -463,6 +469,26 @@ For compilers, like ``clang``, that do not support Fortran, put
 Once you save the file, the configured compilers will show up in the
 list displayed by ``spack compilers``.
 
+You can also add compiler flags to manually configured compilers. The
+valid flags are ``cflags``, ``cxxflags``, ``fflags``, ``cppflags``,
+``ldflags``, and ``ldlibs``. For example,::
+
+    ...
+    chaos_5_x86_64_ib:
+      ...
+      intel@15.0.0:
+          cc: /usr/local/bin/icc-15.0.024-beta
+          cxx: /usr/local/bin/icpc-15.0.024-beta
+          f77: /usr/local/bin/ifort-15.0.024-beta
+          fc: /usr/local/bin/ifort-15.0.024-beta
+          cppflags: -O3 -fPIC
+      ...
+
+These flags will be treated by spack as if they were enterred from
+the command line each time this compiler is used. The compiler wrappers
+then inject those flags into the compiler command. Compiler flags
+enterred from the command line will be discussed in more detail in the
+following section.
 
 .. _sec-specs:
 
@@ -480,7 +506,7 @@ the full syntax of specs.
 
 Here is an example of a much longer spec than we've seen thus far::
 
-   mpileaks @1.2:1.4 %gcc@4.7.5 +debug -qt =bgqos_0 ^callpath @1.1 %gcc@4.7.2
+   mpileaks @1.2:1.4 %gcc@4.7.5 +debug -qt arch=bgq_os ^callpath @1.1 %gcc@4.7.2
 
 If provided to ``spack install``, this will install the ``mpileaks``
 library at some version between ``1.2`` and ``1.4`` (inclusive),
@@ -498,8 +524,12 @@ More formally, a spec consists of the following pieces:
 * ``%`` Optional compiler specifier, with an optional compiler version
   (``gcc`` or ``gcc@4.7.3``)
 * ``+`` or ``-`` or ``~`` Optional variant specifiers (``+debug``,
-  ``-qt``, or ``~qt``)
-* ``=`` Optional architecture specifier (``bgqos_0``)
+  ``-qt``, or ``~qt``) for boolean variants
+* ``name=<value>`` Optional variant specifiers that are not restricted to
+boolean variants
+* ``name=<value>`` Optional compiler flag specifiers. Valid flag names are
+``cflags``, ``cxxflags``, ``fflags``, ``cppflags``, ``ldflags``, and ``ldlibs``.
+* ``arch=<value>`` Optional architecture specifier (``arch=bgq_os``)
 * ``^`` Dependency specs (``^callpath@1.1``)
 
 There are two things to notice here.  The first is that specs are
@@ -579,7 +609,7 @@ compilers, variants, and architectures just like any other spec.
 Specifiers are associated with the nearest package name to their left.
 For example, above, ``@1.1`` and ``%gcc@4.7.2`` associates with the
 ``callpath`` package, while ``@1.2:1.4``, ``%gcc@4.7.5``, ``+debug``,
-``-qt``, and ``=bgqos_0`` all associate with the ``mpileaks`` package.
+``-qt``, and ``arch=bgq_os`` all associate with the ``mpileaks`` package.
 
 In the diagram above, ``mpileaks`` depends on ``mpich`` with an
 unspecified version, but packages can depend on other packages with
@@ -635,22 +665,25 @@ based on site policies.
 Variants
 ~~~~~~~~~~~~~~~~~~~~~~~
 
-.. Note::
-
-   Variants are not yet supported, but will be in the next Spack
-   release (0.9), due in Q2 2015.
-
-Variants are named options associated with a particular package, and
-they can be turned on or off.  For example, above, supplying
-``+debug`` causes ``mpileaks`` to be built with debug flags.  The
-names of particular variants available for a package depend on what
-was provided by the package author.  ``spack info <package>`` will
+Variants are named options associated with a particular package. They are
+optional, as each package must provide default values for each variant it
+makes available. Variants can be specified using
+a flexible parameter syntax ``name=<value>``. For example,
+``spack install libelf debug=True`` will install libelf build with debug
+flags. The names of particular variants available for a package depend on
+what was provided by the package author. ``spack into <package>`` will
 provide information on what build variants are available.
 
-Depending on the package a variant may be on or off by default.  For
-``mpileaks`` here, ``debug`` is off by default, and we turned it on
-with ``+debug``.  If a package is on by default you can turn it off by
-either adding ``-name`` or ``~name`` to the spec.
+For compatibility with earlier versions, variants which happen to be
+boolean in nature can be specified by a syntax that represents turning
+options on and off. For example, in the previous spec we could have
+supplied ``libelf +debug`` with the same effect of enabling the debug
+compile time option for the libelf package.
+
+Depending on the package a variant may have any default value.  For
+``libelf`` here, ``debug`` is ``False`` by default, and we turned it on
+with ``debug=True`` or ``+debug``.  If a package is ``True`` by default
+you can turn it off by either adding ``-name`` or ``~name`` to the spec.
 
 There are two syntaxes here because, depending on context, ``~`` and
 ``-`` may mean different things.  In most shells, the following will
@@ -662,7 +695,7 @@ result in the shell performing home directory substitution:
    mpileaks~debug    # use this instead
 
 If there is a user called ``debug``, the ``~`` will be incorrectly
-expanded.  In this situation, you would want to write ``mpileaks
+expanded.  In this situation, you would want to write ``libelf
 -debug``.  However, ``-`` can be ambiguous when included after a
 package name without spaces:
 
@@ -677,12 +710,35 @@ package, not a request for ``mpileaks`` built without ``debug``
 options.  In this scenario, you should write ``mpileaks~debug`` to
 avoid ambiguity.
 
-When spack normalizes specs, it prints them out with no spaces and
-uses only ``~`` for disabled variants.  We allow ``-`` and spaces on
-the command line is provided for convenience and legibility.
+When spack normalizes specs, it prints them out with no spaces boolean
+variants using the backwards compatibility syntax and uses only ``~``
+for disabled boolean variants.  We allow ``-`` and spaces on the command
+line is provided for convenience and legibility.
+
 
+Compiler Flags
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Compiler flags are specified using the same syntax as non-boolean variants,
+but fulfill a different purpose. While the function of a variant is set by
+the package, compiler flags are used by the compiler wrappers to inject
+flags into the compile line of the build. Additionally, compiler flags are
+inherited by dependencies. ``spack install libdwarf cppflags=\"-g\"`` will
+install both libdwarf and libelf with the ``-g`` flag injected into their
+compile line.
+
+Notice that the value of the compiler flags must be escape quoted on the
+command line. From within python files, the same spec would be specified
+``libdwarf cppflags="-g"``. This is necessary because of how the shell
+handles the quote symbols.
 
-Architecture specifier
+The six compiler flags are injected in the order of implicit make commands
+in gnu autotools. If all flags are set, the order is
+``$cppflags $cflags|$cxxflags $ldflags command $ldlibs`` for C and C++ and
+``$fflags $cppflags $ldflags command $ldlibs`` for fortran.
+
+
+Architecture specifiers
 ~~~~~~~~~~~~~~~~~~~~~~~
 
 .. Note::
@@ -690,12 +746,9 @@ Architecture specifier
    Architecture specifiers are part of specs but are not yet
    functional. They will be in Spack version 1.0, due in Q3 2015.
 
-The architecture specifier starts with a ``=`` and also comes after
-some package name within a spec.  It allows a user to specify a
-particular architecture for the package to be built.  This is mostly
-used for architectures that need cross-compilation, and in most cases,
-users will not need to specify the architecture when they install a
-package.
+The architecture specifier looks identical to a variant specifier for a
+non-boolean variant. The architecture can be specified only using the
+reserved name ``arch`` (``arch=bgq_os``).
 
 
 .. _sec-virtual-dependencies:
@@ -773,6 +826,23 @@ any MPI implementation will do.  If another package depends on
 error.  Likewise, if you try to plug in some package that doesn't
 provide MPI, Spack will raise an error.
 
+Specifying Specs by Hash
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Complicated specs can become cumbersome to enter on the command line,
+especially when many of the qualifications are necessary to
+distinguish between similar installs, for example when using the
+``uninstall`` command. To avoid this, when referencing an existing spec,
+Spack allows you to reference specs by their hash. We previously
+discussed the spec hash that Spack computes. In place of a spec in any
+command, substitute ``/<hash>`` where ``<hash>`` is any amount from
+the beginning of a spec hash. If the given spec hash is sufficient
+to be unique, Spack will replace the reference with the spec to which
+it refers. Otherwise, it will prompt for a more qualified hash.
+
+Note that this will not work to reinstall a depencency uninstalled by
+``spack uninstall -f``.
+
 .. _spack-providers:
 
 ``spack providers``
@@ -1002,8 +1072,8 @@ than one installed package matches it), then Spack will warn you:
 
    $ spack load libelf
    ==> Error: Multiple matches for spec libelf.  Choose one:
-   libelf@0.8.13%gcc@4.4.7=chaos_5_x86_64_ib
-   libelf@0.8.13%intel@15.0.0=chaos_5_x86_64_ib
+   libelf@0.8.13%gcc@4.4.7 arch=chaos_5_x86_64_ib
+   libelf@0.8.13%intel@15.0.0 arch=chaos_5_x86_64_ib
 
 You can either type the ``spack load`` command again with a fully
 qualified argument, or you can add just enough extra constraints to
@@ -1251,6 +1321,120 @@ regenerate all module and dotkit files from scratch:
 
 .. _extensions:
 
+Filesystem Views
+-------------------------------
+
+.. Maybe this is not the right location for this documentation.
+
+The Spack installation area allows for many package installation trees
+to coexist and gives the user choices as to what versions and variants
+of packages to use.  To use them, the user must rely on a way to
+aggregate a subset of those packages.  The section on Environment
+Modules gives one good way to do that which relies on setting various
+environment variables.  An alternative way to aggregate is through
+**filesystem views**.
+
+A filesystem view is a single directory tree which is the union of the
+directory hierarchies of the individual package installation trees
+that have been included.  The files of the view's installed packages
+are brought into the view by symbolic or hard links back to their
+location in the original Spack installation area.  As the view is
+formed, any clashes due to a file having the exact same path in its
+package installation tree are handled in a first-come-first-served
+basis and a warning is printed.  Packages and their dependencies can
+be both added and removed.  During removal, empty directories will be
+purged.  These operations can be limited to pertain to just the
+packages listed by the user or to exclude specific dependencies and
+they allow for software installed outside of Spack to coexist inside
+the filesystem view tree.
+
+By its nature, a filesystem view represents a particular choice of one
+set of packages among all the versions and variants that are available
+in the Spack installation area.  It is thus equivalent to the
+directory hiearchy that might exist under ``/usr/local``.  While this
+limits a view to including only one version/variant of any package, it
+provides the benefits of having a simpler and traditional layout which
+may be used without any particular knowledge that its packages were
+built by Spack.
+
+Views can be used for a variety of purposes including:
+
+- A central installation in a traditional layout, eg ``/usr/local`` maintained over time by the sysadmin.
+- A self-contained installation area which may for the basis of a top-level atomic versioning scheme, eg ``/opt/pro`` vs ``/opt/dev``.
+- Providing an atomic and monolithic binary distribution, eg for delivery as a single tarball.
+- Producing ephemeral testing or developing environments.
+
+Using Filesystem Views
+~~~~~~~~~~~~~~~~~~~~~~
+
+A filesystem view is created and packages are linked in by the ``spack
+view`` command's ``symlink`` and ``hardlink`` sub-commands.  The
+``spack view remove`` command can be used to unlink some or all of the
+filesystem view.
+
+The following example creates a filesystem view based
+on an installed ``cmake`` package and then removes from the view the
+files in the ``cmake`` package while retaining its dependencies.
+
+.. code-block:: sh
+
+    
+    $ spack view -v symlink myview cmake@3.5.2
+    ==> Linking package: "ncurses"
+    ==> Linking package: "zlib"
+    ==> Linking package: "openssl"
+    ==> Linking package: "cmake"
+    
+    $ ls myview/
+    bin  doc  etc  include  lib  share
+
+    $ ls myview/bin/
+    captoinfo  clear  cpack     ctest    infotocap        openssl  tabs  toe   tset
+    ccmake     cmake  c_rehash  infocmp  ncurses6-config  reset    tic   tput
+    
+    $ spack view -v -d false rm myview cmake@3.5.2
+    ==> Removing package: "cmake"
+    
+    $ ls myview/bin/
+    captoinfo  c_rehash  infotocap        openssl  tabs  toe   tset
+    clear      infocmp   ncurses6-config  reset    tic   tput
+
+
+Limitations of Filesystem Views
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This section describes some limitations that should be considered in
+using filesystems views.  
+
+Filesystem views are merely organizational.  The binary executable
+programs, shared libraries and other build products found in a view
+are mere links into the "real" Spack installation area.  If a view is
+built with symbolic links it requires the Spack-installed package to
+be kept in place.  Building a view with hardlinks removes this
+requirement but any internal paths (eg, rpath or ``#!`` interpreter
+specifications) will still require the Spack-installed package files
+to be in place.
+
+.. FIXME: reference the relocation work of Hegner and Gartung.
+
+As described above, when a view is built only a single instance of a
+file may exist in the unified filesystem tree.  If more than one
+package provides a file at the same path (relative to its own root)
+then it is the first package added to the view that "wins".  A warning
+is printed and it is up to the user to determine if the conflict
+matters.
+
+It is up to the user to assure a consistent view is produced.  In
+particular if the user excludes packages, limits the following of
+dependencies or removes packages the view may become inconsistent.  In
+particular, if two packages require the same sub-tree of dependencies,
+removing one package (recursively) will remove its dependencies and
+leave the other package broken.
+
+
+
+
+
 Extensions & Python support
 ------------------------------------
 
@@ -1282,7 +1466,7 @@ You can find extensions for your Python installation like this:
 .. code-block:: sh
 
    $ spack extensions python
-   ==> python@2.7.8%gcc@4.4.7=chaos_5_x86_64_ib-703c7a96
+   ==> python@2.7.8%gcc@4.4.7 arch=chaos_5_x86_64_ib-703c7a96
    ==> 36 extensions:
    geos          py-ipython     py-pexpect    py-pyside            py-sip
    py-basemap    py-libxml2     py-pil        py-pytz              py-six
@@ -1372,9 +1556,9 @@ installation:
 .. code-block:: sh
 
    $ spack activate py-numpy
-   ==> Activated extension py-setuptools@11.3.1%gcc@4.4.7=chaos_5_x86_64_ib-3c74eb69 for python@2.7.8%gcc@4.4.7.
-   ==> Activated extension py-nose@1.3.4%gcc@4.4.7=chaos_5_x86_64_ib-5f70f816 for python@2.7.8%gcc@4.4.7.
-   ==> Activated extension py-numpy@1.9.1%gcc@4.4.7=chaos_5_x86_64_ib-66733244 for python@2.7.8%gcc@4.4.7.
+   ==> Activated extension py-setuptools@11.3.1%gcc@4.4.7 arch=chaos_5_x86_64_ib-3c74eb69 for python@2.7.8%gcc@4.4.7.
+   ==> Activated extension py-nose@1.3.4%gcc@4.4.7 arch=chaos_5_x86_64_ib-5f70f816 for python@2.7.8%gcc@4.4.7.
+   ==> Activated extension py-numpy@1.9.1%gcc@4.4.7 arch=chaos_5_x86_64_ib-66733244 for python@2.7.8%gcc@4.4.7.
 
 Several things have happened here.  The user requested that
 ``py-numpy`` be activated in the ``python`` installation it was built
@@ -1389,7 +1573,7 @@ packages listed as activated:
 .. code-block:: sh
 
    $ spack extensions python
-   ==> python@2.7.8%gcc@4.4.7=chaos_5_x86_64_ib-703c7a96
+   ==> python@2.7.8%gcc@4.4.7  arch=chaos_5_x86_64_ib-703c7a96
    ==> 36 extensions:
    geos          py-ipython     py-pexpect    py-pyside            py-sip
    py-basemap    py-libxml2     py-pil        py-pytz              py-six
@@ -1437,7 +1621,7 @@ dependencies, you can use ``spack activate -f``:
 .. code-block:: sh
 
    $ spack activate -f py-numpy
-   ==> Activated extension py-numpy@1.9.1%gcc@4.4.7=chaos_5_x86_64_ib-66733244 for python@2.7.8%gcc@4.4.7.
+   ==> Activated extension py-numpy@1.9.1%gcc@4.4.7 arch=chaos_5_x86_64_ib-66733244 for python@2.7.8%gcc@4.4.7.
 
 .. _spack-deactivate:
 
diff --git a/lib/spack/docs/configuration.rst b/lib/spack/docs/configuration.rst
index c0b79a7f44..c613071c65 100644
--- a/lib/spack/docs/configuration.rst
+++ b/lib/spack/docs/configuration.rst
@@ -70,9 +70,9 @@ directory. Here's an example of an external configuration:
    packages:
       openmpi:
          paths:
-            openmpi@1.4.3%gcc@4.4.7=chaos_5_x86_64_ib: /opt/openmpi-1.4.3
-            openmpi@1.4.3%gcc@4.4.7=chaos_5_x86_64_ib+debug: /opt/openmpi-1.4.3-debug
-            openmpi@1.6.5%intel@10.1=chaos_5_x86_64_ib: /opt/openmpi-1.6.5-intel
+            openmpi@1.4.3%gcc@4.4.7 arch=chaos_5_x86_64_ib: /opt/openmpi-1.4.3
+            openmpi@1.4.3%gcc@4.4.7 arch=chaos_5_x86_64_ib+debug: /opt/openmpi-1.4.3-debug
+            openmpi@1.6.5%intel@10.1 arch=chaos_5_x86_64_ib: /opt/openmpi-1.6.5-intel
 
 This example lists three installations of OpenMPI, one built with gcc,
 one built with gcc and debug information, and another built with Intel.
@@ -108,9 +108,9 @@ be:
   packages:
     openmpi:
       paths:
-        openmpi@1.4.3%gcc@4.4.7=chaos_5_x86_64_ib: /opt/openmpi-1.4.3
-        openmpi@1.4.3%gcc@4.4.7=chaos_5_x86_64_ib+debug: /opt/openmpi-1.4.3-debug
-        openmpi@1.6.5%intel@10.1=chaos_5_x86_64_ib: /opt/openmpi-1.6.5-intel
+        openmpi@1.4.3%gcc@4.4.7 arch=chaos_5_x86_64_ib: /opt/openmpi-1.4.3
+        openmpi@1.4.3%gcc@4.4.7 arch=chaos_5_x86_64_ib+debug: /opt/openmpi-1.4.3-debug
+        openmpi@1.6.5%intel@10.1 arch=chaos_5_x86_64_ib: /opt/openmpi-1.6.5-intel
       buildable: False
 
 The addition of the ``buildable`` flag tells Spack that it should never build
diff --git a/lib/spack/docs/features.rst b/lib/spack/docs/features.rst
index 0998ba8da4..27a3b4b435 100644
--- a/lib/spack/docs/features.rst
+++ b/lib/spack/docs/features.rst
@@ -31,14 +31,21 @@ platform, all on the command line.
    # Specify a compiler (and its version), with %
    $ spack install mpileaks@1.1.2 %gcc@4.7.3
 
-   # Add special compile-time options with +
+   # Add special compile-time options by name
+   $ spack install mpileaks@1.1.2 %gcc@4.7.3 debug=True
+
+   # Add special boolean compile-time options with +
    $ spack install mpileaks@1.1.2 %gcc@4.7.3 +debug
 
-   # Cross-compile for a different architecture with =
-   $ spack install mpileaks@1.1.2 =bgqos_0
+   # Add compiler flags using the conventional names
+   $ spack install mpileaks@1.1.2 %gcc@4.7.3 cppflags=\"-O3 -floop-block\"
+
+   # Cross-compile for a different architecture with arch=
+   $ spack install mpileaks@1.1.2 arch=bgqos_0
 
-Users can specify as many or few options as they care about.  Spack
-will fill in the unspecified values with sensible defaults.
+Users can specify as many or few options as they care about. Spack
+will fill in the unspecified values with sensible defaults. The two listed
+syntaxes for variants are identical when the value is boolean.
 
 
 Customize dependencies
diff --git a/lib/spack/docs/packaging_guide.rst b/lib/spack/docs/packaging_guide.rst
index 63c411ffb5..1f83f611b0 100644
--- a/lib/spack/docs/packaging_guide.rst
+++ b/lib/spack/docs/packaging_guide.rst
@@ -1221,11 +1221,13 @@ just as easily provide a version range:
 
    depends_on("libelf@0.8.2:0.8.4:")
 
-Or a requirement for a particular variant:
+Or a requirement for a particular variant or compiler flags:
 
 .. code-block:: python
 
    depends_on("libelf@0.8+debug")
+   depends_on('libelf debug=True')
+   depends_on('libelf cppflags="-fPIC")
 
 Both users *and* package authors can use the same spec syntax to refer
 to different package configurations.  Users use the spec syntax on the
@@ -1623,21 +1625,21 @@ the user runs ``spack install`` and the time the ``install()`` method
 is called.  The concretized version of the spec above might look like
 this::
 
-   mpileaks@2.3%gcc@4.7.3=linux-ppc64
-       ^callpath@1.0%gcc@4.7.3+debug=linux-ppc64
-           ^dyninst@8.1.2%gcc@4.7.3=linux-ppc64
-               ^libdwarf@20130729%gcc@4.7.3=linux-ppc64
-                   ^libelf@0.8.11%gcc@4.7.3=linux-ppc64
-           ^mpich@3.0.4%gcc@4.7.3=linux-ppc64
+   mpileaks@2.3%gcc@4.7.3 arch=linux-ppc64
+       ^callpath@1.0%gcc@4.7.3+debug arch=linux-ppc64
+           ^dyninst@8.1.2%gcc@4.7.3 arch=linux-ppc64
+               ^libdwarf@20130729%gcc@4.7.3 arch=linux-ppc64
+                   ^libelf@0.8.11%gcc@4.7.3 arch=linux-ppc64
+           ^mpich@3.0.4%gcc@4.7.3 arch=linux-ppc64
 
 .. graphviz::
 
    digraph {
-       "mpileaks@2.3\n%gcc@4.7.3\n=linux-ppc64" -> "mpich@3.0.4\n%gcc@4.7.3\n=linux-ppc64"
-       "mpileaks@2.3\n%gcc@4.7.3\n=linux-ppc64" -> "callpath@1.0\n%gcc@4.7.3+debug\n=linux-ppc64" -> "mpich@3.0.4\n%gcc@4.7.3\n=linux-ppc64"
-       "callpath@1.0\n%gcc@4.7.3+debug\n=linux-ppc64" -> "dyninst@8.1.2\n%gcc@4.7.3\n=linux-ppc64"
-       "dyninst@8.1.2\n%gcc@4.7.3\n=linux-ppc64" -> "libdwarf@20130729\n%gcc@4.7.3\n=linux-ppc64" -> "libelf@0.8.11\n%gcc@4.7.3\n=linux-ppc64"
-       "dyninst@8.1.2\n%gcc@4.7.3\n=linux-ppc64" -> "libelf@0.8.11\n%gcc@4.7.3\n=linux-ppc64"
+       "mpileaks@2.3\n%gcc@4.7.3\n arch=linux-ppc64" -> "mpich@3.0.4\n%gcc@4.7.3\n arch=linux-ppc64"
+       "mpileaks@2.3\n%gcc@4.7.3\n arch=linux-ppc64" -> "callpath@1.0\n%gcc@4.7.3+debug\n arch=linux-ppc64" -> "mpich@3.0.4\n%gcc@4.7.3\n arch=linux-ppc64"
+       "callpath@1.0\n%gcc@4.7.3+debug\n arch=linux-ppc64" -> "dyninst@8.1.2\n%gcc@4.7.3\n arch=linux-ppc64"
+       "dyninst@8.1.2\n%gcc@4.7.3\n arch=linux-ppc64" -> "libdwarf@20130729\n%gcc@4.7.3\n arch=linux-ppc64" -> "libelf@0.8.11\n%gcc@4.7.3\n arch=linux-ppc64"
+       "dyninst@8.1.2\n%gcc@4.7.3\n arch=linux-ppc64" -> "libelf@0.8.11\n%gcc@4.7.3\n arch=linux-ppc64"
    }
 
 Here, all versions, compilers, and platforms are filled in, and there
@@ -1666,9 +1668,9 @@ running ``spack spec``.  For example:
        ^libdwarf
            ^libelf
 
-   dyninst@8.0.1%gcc@4.7.3=linux-ppc64
-       ^libdwarf@20130729%gcc@4.7.3=linux-ppc64
-           ^libelf@0.8.13%gcc@4.7.3=linux-ppc64
+   dyninst@8.0.1%gcc@4.7.3 arch=linux-ppc64
+       ^libdwarf@20130729%gcc@4.7.3 arch=linux-ppc64
+           ^libelf@0.8.13%gcc@4.7.3 arch=linux-ppc64
 
 This is useful when you want to know exactly what Spack will do when
 you ask for a particular spec.
@@ -1908,6 +1910,12 @@ the command line.
     ``$rpath_flag`` can be overriden on a compiler specific basis in
     ``lib/spack/spack/compilers/$compiler.py``.
 
+The compiler wrappers also pass the compiler flags specified by the user from
+the command line (``cflags``, ``cxxflags``, ``fflags``, ``cppflags``, ``ldflags``,
+and/or ``ldlibs``). They do not override the canonical autotools flags with the
+same names (but in ALL-CAPS) that may be passed into the build by particularly
+challenging package scripts.
+
 Compiler flags
 ~~~~~~~~~~~~~~
 In rare circumstances such as compiling and running small unit tests, a package
@@ -2154,12 +2162,12 @@ example:
        def install(self, prefix):
            # Do default install
 
-       @when('=chaos_5_x86_64_ib')
+       @when('arch=chaos_5_x86_64_ib')
        def install(self, prefix):
            # This will be executed instead of the default install if
            # the package's sys_type() is chaos_5_x86_64_ib.
 
-       @when('=bgqos_0")
+       @when('arch=bgqos_0")
        def install(self, prefix):
            # This will be executed if the package's sys_type is bgqos_0
 
@@ -2749,11 +2757,11 @@ build it:
    $ spack stage libelf
    ==> Trying to fetch from http://www.mr511.de/software/libelf-0.8.13.tar.gz
    ######################################################################## 100.0%
-   ==> Staging archive: /Users/gamblin2/src/spack/var/spack/stage/libelf@0.8.13%gcc@4.8.3=linux-ppc64/libelf-0.8.13.tar.gz
-   ==> Created stage in /Users/gamblin2/src/spack/var/spack/stage/libelf@0.8.13%gcc@4.8.3=linux-ppc64.
+   ==> Staging archive: /Users/gamblin2/src/spack/var/spack/stage/libelf@0.8.13%gcc@4.8.3 arch=linux-ppc64/libelf-0.8.13.tar.gz
+   ==> Created stage in /Users/gamblin2/src/spack/var/spack/stage/libelf@0.8.13%gcc@4.8.3 arch=linux-ppc64.
    $ spack cd libelf
    $ pwd
-   /Users/gamblin2/src/spack/var/spack/stage/libelf@0.8.13%gcc@4.8.3=linux-ppc64/libelf-0.8.13
+   /Users/gamblin2/src/spack/var/spack/stage/libelf@0.8.13%gcc@4.8.3 arch=linux-ppc64/libelf-0.8.13
 
 ``spack cd`` here changed he current working directory to the
 directory containing the expanded ``libelf`` source code.  There are a
diff --git a/lib/spack/env/cc b/lib/spack/env/cc
index 9758b74f37..bf98b4c354 100755
--- a/lib/spack/env/cc
+++ b/lib/spack/env/cc
@@ -174,6 +174,28 @@ if [[ -z $command ]]; then
     die "ERROR: Compiler '$SPACK_COMPILER_SPEC' does not support compiling $language programs."
 fi
 
+#
+# Filter '.' and Spack environment directories out of PATH so that
+# this script doesn't just call itself
+#
+IFS=':' read -ra env_path <<< "$PATH"
+IFS=':' read -ra spack_env_dirs <<< "$SPACK_ENV_PATH"
+spack_env_dirs+=("" ".")
+PATH=""
+for dir in "${env_path[@]}"; do
+    addpath=true
+    for env_dir in "${spack_env_dirs[@]}"; do
+        if [[ $dir == $env_dir ]]; then
+            addpath=false
+            break
+        fi
+    done
+    if $addpath; then
+        PATH="${PATH:+$PATH:}$dir"
+    fi
+done
+export PATH
+
 if [[ $mode == vcheck ]]; then
     exec ${command} "$@"
 fi
@@ -286,28 +308,6 @@ unset LD_LIBRARY_PATH
 unset LD_RUN_PATH
 unset DYLD_LIBRARY_PATH
 
-#
-# Filter '.' and Spack environment directories out of PATH so that
-# this script doesn't just call itself
-#
-IFS=':' read -ra env_path <<< "$PATH"
-IFS=':' read -ra spack_env_dirs <<< "$SPACK_ENV_PATH"
-spack_env_dirs+=("" ".")
-PATH=""
-for dir in "${env_path[@]}"; do
-    addpath=true
-    for env_dir in "${spack_env_dirs[@]}"; do
-        if [[ $dir == $env_dir ]]; then
-            addpath=false
-            break
-        fi
-    done
-    if $addpath; then
-        PATH="${PATH:+$PATH:}$dir"
-    fi
-done
-export PATH
-
 full_command=("$command" "${args[@]}")
 
 # In test command mode, write out full command for Spack tests.
@@ -324,8 +324,8 @@ fi
 if [[ $SPACK_DEBUG == TRUE ]]; then
     input_log="$SPACK_DEBUG_LOG_DIR/spack-cc-$SPACK_SHORT_SPEC.in.log"
     output_log="$SPACK_DEBUG_LOG_DIR/spack-cc-$SPACK_SHORT_SPEC.out.log"
-    echo "[$mode] $command $input_command" >> $input_log
-    echo "[$mode] ${full_command[@]}" >> $output_log
+    echo "[$mode] $command $input_command" >> "$input_log"
+    echo "[$mode] ${full_command[@]}" >> "$output_log"
 fi
 
 exec "${full_command[@]}"
diff --git a/lib/spack/llnl/util/tty/__init__.py b/lib/spack/llnl/util/tty/__init__.py
index c638b113fd..ee81e11a20 100644
--- a/lib/spack/llnl/util/tty/__init__.py
+++ b/lib/spack/llnl/util/tty/__init__.py
@@ -64,12 +64,14 @@ def info(message, *args, **kwargs):
     format = kwargs.get('format', '*b')
     stream = kwargs.get('stream', sys.stdout)
     wrap   = kwargs.get('wrap', False)
+    break_long_words = kwargs.get('break_long_words', False)
 
     cprint("@%s{==>} %s" % (format, cescape(str(message))), stream=stream)
     for arg in args:
         if wrap:
             lines = textwrap.wrap(
-                str(arg), initial_indent=indent, subsequent_indent=indent)
+                str(arg), initial_indent=indent, subsequent_indent=indent,
+                break_long_words=break_long_words)
             for line in lines:
                 stream.write(line + '\n')
         else:
diff --git a/lib/spack/llnl/util/tty/colify.py b/lib/spack/llnl/util/tty/colify.py
index 429ba45882..81a83691d7 100644
--- a/lib/spack/llnl/util/tty/colify.py
+++ b/lib/spack/llnl/util/tty/colify.py
@@ -198,8 +198,13 @@ def colify(elts, **options):
         for col in xrange(cols):
             elt = col * rows + row
             width = config.widths[col] + cextra(elts[elt])
-            fmt = '%%-%ds' % width
-            output.write(fmt % elts[elt])
+            if col < cols - 1:
+                fmt = '%%-%ds' % width
+                output.write(fmt % elts[elt])
+            else:
+                # Don't pad the rightmost column (sapces can wrap on
+                # small teriminals if one line is overlong)
+                output.write(elts[elt])
 
         output.write("\n")
         row += 1
diff --git a/lib/spack/spack/__init__.py b/lib/spack/spack/__init__.py
index 927e4c1422..965e3a7f78 100644
--- a/lib/spack/spack/__init__.py
+++ b/lib/spack/spack/__init__.py
@@ -39,7 +39,9 @@ spack_file = join_path(spack_root, "bin", "spack")
 lib_path       = join_path(spack_root, "lib", "spack")
 build_env_path = join_path(lib_path, "env")
 module_path    = join_path(lib_path, "spack")
+platform_path  = join_path(module_path, 'platforms')
 compilers_path = join_path(module_path, "compilers")
+operating_system_path = join_path(module_path, 'operating_systems')
 test_path      = join_path(module_path, "test")
 hooks_path     = join_path(module_path, "hooks")
 var_path       = join_path(spack_root, "var", "spack")
@@ -109,7 +111,7 @@ concretizer = DefaultConcretizer()
 
 # Version information
 from spack.version import Version
-spack_version = Version("0.9")
+spack_version = Version("0.9.1")
 
 #
 # Executables used by Spack
diff --git a/lib/spack/spack/abi.py b/lib/spack/spack/abi.py
index 91d1d2003d..38cff62af4 100644
--- a/lib/spack/spack/abi.py
+++ b/lib/spack/spack/abi.py
@@ -35,8 +35,9 @@ class ABI(object):
        The current implementation is rather rough and could be improved."""
 
     def architecture_compatible(self, parent, child):
-        """Returns true iff the parent and child specs have ABI compatible architectures."""
-        return not parent.architecture or not child.architecture or parent.architecture == child.architecture
+        """Returns true iff the parent and child specs have ABI compatible targets."""
+        return not parent.architecture or not child.architecture \
+                        or parent.architecture == child.architecture
 
 
     @memoized
diff --git a/lib/spack/spack/architecture.py b/lib/spack/spack/architecture.py
index b14cb2bea2..cbac7b41d6 100644
--- a/lib/spack/spack/architecture.py
+++ b/lib/spack/spack/architecture.py
@@ -22,68 +22,498 @@
 # License along with this program; if not, write to the Free Software
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
+"""
+This module contains all the elements that are required to create an
+architecture object. These include, the target processor, the operating system,
+and the architecture platform (i.e. cray, darwin, linux, bgq, etc) classes.
+
+On a multiple architecture machine, the architecture spec field can be set to
+build a package against any target and operating system that is present on the
+platform. On Cray platforms or any other architecture that has different front
+and back end environments, the operating system will determine the method of
+compiler
+detection.
+
+There are two different types of compiler detection:
+    1. Through the $PATH env variable (front-end detection)
+    2. Through the tcl module system. (back-end detection)
+
+Depending on which operating system is specified, the compiler will be detected
+using one of those methods.
+
+For platforms such as linux and darwin, the operating system is autodetected
+and the target is set to be x86_64.
+
+The command line syntax for specifying an architecture is as follows:
+
+    target=<Target name> os=<OperatingSystem name>
+
+If the user wishes to use the defaults, either target or os can be left out of
+the command line and Spack will concretize using the default. These defaults
+are set in the 'platforms/' directory which contains the different subclasses
+for platforms. If the machine has multiple architectures, the user can
+also enter front-end, or fe or back-end or be. These settings will concretize
+to their respective front-end and back-end targets and operating systems.
+Additional platforms can be added by creating a subclass of Platform
+and adding it inside the platform directory.
+
+Platforms are an abstract class that are extended by subclasses. If the user
+wants to add a new type of platform (such as cray_xe), they can create a
+subclass and set all the class attributes such as priority, front_target,
+back_target, front_os, back_os. Platforms also contain a priority class
+attribute. A lower number signifies higher priority. These numbers are
+arbitrarily set and can be changed though often there isn't much need unless a
+new platform is added and the user wants that to be detected first.
+
+Targets are created inside the platform subclasses. Most architecture
+(like linux, and darwin) will have only one target (x86_64) but in the case of
+Cray machines, there is both a frontend and backend processor. The user can
+specify which targets are present on front-end and back-end architecture
+
+Depending on the platform, operating systems are either auto-detected or are
+set. The user can set the front-end and back-end operating setting by the class
+attributes front_os and back_os. The operating system as described earlier,
+will be responsible for compiler detection.
+"""
 import os
-import re
-import platform
+import imp
+import inspect
 
-from llnl.util.lang import memoized
+from llnl.util.lang import memoized, list_modules, key_ordering
+from llnl.util.filesystem import join_path
+import llnl.util.tty as tty
 
 import spack
+import spack.compilers
+from spack.util.naming import mod_to_class
+from spack.util.environment import get_path
+from spack.util.multiproc import parmap
 import spack.error as serr
 
 
 class InvalidSysTypeError(serr.SpackError):
     def __init__(self, sys_type):
-        super(InvalidSysTypeError,
-              self).__init__("Invalid sys_type value for Spack: " + sys_type)
+        super(InvalidSysTypeError, self).__init__(
+            "Invalid sys_type value for Spack: " + sys_type)
 
 
 class NoSysTypeError(serr.SpackError):
     def __init__(self):
-        super(NoSysTypeError,
-              self).__init__("Could not determine sys_type for this machine.")
+        super(NoSysTypeError, self).__init__(
+            "Could not determine sys_type for this machine.")
+
+
+@key_ordering
+class Target(object):
+    """ Target is the processor of the host machine.
+        The host machine may have different front-end and back-end targets,
+        especially if it is a Cray machine. The target will have a name and
+        also the module_name (e.g craype-compiler). Targets will also
+        recognize which platform they came from using the set_platform method.
+        Targets will have compiler finding strategies
+    """
+
+    def __init__(self, name, module_name=None):
+        self.name = name  # case of cray "ivybridge" but if it's x86_64
+        self.module_name = module_name  # craype-ivybridge
+
+    # Sets only the platform name to avoid recursiveness
+
+    def _cmp_key(self):
+        return (self.name, self.module_name)
+
+    def __repr__(self):
+        return self.__str__()
+
+    def __str__(self):
+        return self.name
+
+
+@key_ordering
+class Platform(object):
+    """ Abstract class that each type of Platform will subclass.
+        Will return a instance of it once it
+        is returned
+    """
+
+    priority        = None  # Subclass sets number. Controls detection order
+    front_end       = None
+    back_end        = None
+    default         = None  # The default back end target. On cray ivybridge
+
+    front_os        = None
+    back_os         = None
+    default_os      = None
+
+    def __init__(self, name):
+        self.targets = {}
+        self.operating_sys = {}
+        self.name = name
+
+    def add_target(self, name, target):
+        """Used by the platform specific subclass to list available targets.
+        Raises an error if the platform specifies a name
+        that is reserved by spack as an alias.
+        """
+        if name in ['frontend', 'fe', 'backend', 'be', 'default_target']:
+            raise ValueError(
+                "%s is a spack reserved alias "
+                "and cannot be the name of a target" % name)
+        self.targets[name] = target
+
+    def target(self, name):
+        """This is a getter method for the target dictionary
+        that handles defaulting based on the values provided by default,
+        front-end, and back-end. This can be overwritten
+        by a subclass for which we want to provide further aliasing options.
+        """
+        if name == 'default_target':
+            name = self.default
+        elif name == 'frontend' or name == 'fe':
+            name = self.front_end
+        elif name == 'backend' or name == 'be':
+            name = self.back_end
+
+        return self.targets.get(name, None)
+
+    def add_operating_system(self, name, os_class):
+        """ Add the operating_system class object into the
+            platform.operating_sys dictionary
+        """
+        if name in ['frontend', 'fe', 'backend', 'be', 'default_os']:
+            raise ValueError(
+                "%s is a spack reserved alias "
+                "and cannot be the name of an OS" % name)
+        self.operating_sys[name] = os_class
+
+    def operating_system(self, name):
+        if name == 'default_os':
+            name = self.default_os
+        if name == 'frontend' or name == "fe":
+            name = self.front_os
+        if name == 'backend' or name == 'be':
+            name = self.back_os
+
+        return self.operating_sys.get(name, None)
+
+
+    @classmethod
+    def detect(self):
+        """ Subclass is responsible for implementing this method.
+            Returns True if the Platform class detects that
+            it is the current platform
+            and False if it's not.
+        """
+        raise NotImplementedError()
+
+
+    def __repr__(self):
+        return self.__str__()
+
+
+    def __str__(self):
+        return self.name
+
+
+    def _cmp_key(self):
+        t_keys = ''.join(str(t._cmp_key()) for t in
+                         sorted(self.targets.values()))
+        o_keys = ''.join(str(o._cmp_key()) for o in
+                         sorted(self.operating_sys.values()))
+        return (self.name,
+                self.default,
+                self.front_end,
+                self.back_end,
+                self.default_os,
+                self.front_os,
+                self.back_os,
+                t_keys,
+                o_keys)
+
+
+@key_ordering
+class OperatingSystem(object):
+    """ Operating System will be like a class similar to platform extended
+        by subclasses for the specifics. Operating System will contain the
+        compiler finding logic. Instead of calling two separate methods to
+        find compilers we call find_compilers method for each operating system
+    """
+
+    def __init__(self, name, version):
+        self.name = name
+        self.version = version
+
+    def __str__(self):
+        return self.name + self.version
+
+    def __repr__(self):
+        return self.__str__()
+
+    def _cmp_key(self):
+        return (self.name, self.version)
 
+    def find_compilers(self, *paths):
+        """
+        Return a list of compilers found in the suppied paths.
+        This invokes the find() method for each Compiler class,
+        and appends the compilers detected to a list.
+        """
+        if not paths:
+            paths = get_path('PATH')
+        # Make sure path elements exist, and include /bin directories
+        # under prefixes.
+        filtered_path = []
+        for p in paths:
+            # Eliminate symlinks and just take the real directories.
+            p = os.path.realpath(p)
+            if not os.path.isdir(p):
+                continue
+            filtered_path.append(p)
 
-def get_sys_type_from_spack_globals():
-    """Return the SYS_TYPE from spack globals, or None if it isn't set."""
-    if not hasattr(spack, "sys_type"):
-        return None
-    elif hasattr(spack.sys_type, "__call__"):
-        return spack.sys_type()
+            # Check for a bin directory, add it if it exists
+            bin = join_path(p, 'bin')
+            if os.path.isdir(bin):
+                filtered_path.append(os.path.realpath(bin))
+
+        # Once the paths are cleaned up, do a search for each type of
+        # compiler.  We can spawn a bunch of parallel searches to reduce
+        # the overhead of spelunking all these directories.
+        types = spack.compilers.all_compiler_types()
+        compiler_lists = parmap(lambda cmp_cls:
+                                self.find_compiler(cmp_cls, *filtered_path),
+                                types)
+
+        # ensure all the version calls we made are cached in the parent
+        # process, as well.  This speeds up Spack a lot.
+        clist = reduce(lambda x, y: x+y, compiler_lists)
+        return clist
+
+    def find_compiler(self, cmp_cls, *path):
+        """Try to find the given type of compiler in the user's
+           environment. For each set of compilers found, this returns
+           compiler objects with the cc, cxx, f77, fc paths and the
+           version filled in.
+
+           This will search for compilers with the names in cc_names,
+           cxx_names, etc. and it will group them if they have common
+           prefixes, suffixes, and versions.  e.g., gcc-mp-4.7 would
+           be grouped with g++-mp-4.7 and gfortran-mp-4.7.
+        """
+        dicts = parmap(
+            lambda t: cmp_cls._find_matches_in_path(*t),
+            [(cmp_cls.cc_names,  cmp_cls.cc_version)  + tuple(path),
+             (cmp_cls.cxx_names, cmp_cls.cxx_version) + tuple(path),
+             (cmp_cls.f77_names, cmp_cls.f77_version) + tuple(path),
+             (cmp_cls.fc_names,  cmp_cls.fc_version)  + tuple(path)])
+
+        all_keys = set()
+        for d in dicts:
+            all_keys.update(d)
+
+        compilers = {}
+        for k in all_keys:
+            ver, pre, suf = k
+
+            # Skip compilers with unknown version.
+            if ver == 'unknown':
+                continue
+
+            paths = tuple(pn[k] if k in pn else None for pn in dicts)
+            spec = spack.spec.CompilerSpec(cmp_cls.name, ver)
+
+            if ver in compilers:
+                prev = compilers[ver]
+
+                # prefer the one with more compilers.
+                prev_paths = [prev.cc, prev.cxx, prev.f77, prev.fc]
+                newcount = len([p for p in paths       if p is not None])
+                prevcount = len([p for p in prev_paths if p is not None])
+
+                # Don't add if it's not an improvement over prev compiler.
+                if newcount <= prevcount:
+                    continue
+
+            compilers[ver] = cmp_cls(spec, self, paths)
+
+        return list(compilers.values())
+
+    def to_dict(self):
+        d = {}
+        d['name'] = self.name
+        d['version'] = self.version
+        return d
+
+@key_ordering
+class Arch(object):
+    "Architecture is now a class to help with setting attributes"
+
+    def __init__(self, platform=None, platform_os=None, target=None):
+        self.platform = platform
+        if platform and platform_os:
+                platform_os = self.platform.operating_system(platform_os)
+        self.platform_os = platform_os
+        if platform and target:
+            target = self.platform.target(target)
+        self.target = target
+
+        # Hooks for parser to use when platform is set after target or os
+        self.target_string = None
+        self.os_string = None
+
+    @property
+    def concrete(self):
+        return all((self.platform is not None,
+                    isinstance(self.platform, Platform),
+                    self.platform_os is not None,
+                    isinstance(self.platform_os, OperatingSystem),
+                    self.target is not None, isinstance(self.target, Target)))
+
+    def __str__(self):
+        if self.platform or self.platform_os or self.target:
+            if self.platform.name == 'darwin':
+                os_name = self.platform_os.name if self.platform_os else "None"
+            else:
+                os_name = str(self.platform_os)
+
+            return (str(self.platform) + "-" +
+                    os_name + "-" + str(self.target))
+        else:
+            return ''
+
+
+    def __contains__(self, string):
+        return string in str(self)
+
+
+    def _cmp_key(self):
+        if isinstance(self.platform, Platform):
+            platform = self.platform.name
+        else:
+            platform = self.platform
+        if isinstance(self.platform_os, OperatingSystem):
+            platform_os = self.platform_os.name
+        else:
+            platform_os = self.platform_os
+        if isinstance(self.target, Target):
+            target = self.target.name
+        else:
+            target = self.target
+        return (platform, platform_os, target)
+
+    def to_dict(self):
+        d = {}
+        d['platform'] = str(self.platform) if self.platform else None
+        d['platform_os'] = str(self.platform_os) if self.platform_os else None
+        d['target'] = str(self.target) if self.target else None
+
+        return d
+
+
+def _target_from_dict(target_name, platform=None):
+    """ Creates new instance of target and assigns all the attributes of
+        that target from the dictionary
+    """
+    if not platform:
+        platform = sys_type()
+    return platform.target(target_name)
+
+
+def _operating_system_from_dict(os_name, platform=None):
+    """ uses platform's operating system method to grab the constructed
+        operating systems that are valid on the platform.
+    """
+    if not platform:
+        platform = sys_type()
+    if isinstance(os_name, dict):
+        name = os_name['name']
+        version = os_name['version']
+        return platform.operating_system(name+version)
     else:
-        return spack.sys_type
+        return platform.operating_system(os_name)
+
 
+def _platform_from_dict(platform_name):
+    """ Constructs a platform from a dictionary. """
+    platform_list = all_platforms()
+    for p in platform_list:
+        if platform_name.replace("_", "").lower() == p.__name__.lower():
+            return p()
 
-def get_sys_type_from_environment():
-    """Return $SYS_TYPE or None if it's not defined."""
-    return os.environ.get('SYS_TYPE')
 
+def arch_from_dict(d):
+    """ Uses _platform_from_dict, _operating_system_from_dict, _target_from_dict
+        helper methods to recreate the arch tuple from the dictionary read from
+        a yaml file
+    """
+    arch = Arch()
 
-def get_sys_type_from_platform():
-    """Return the architecture from Python's platform module."""
-    sys_type = platform.system() + '-' + platform.machine()
-    sys_type = re.sub(r'[^\w-]', '_', sys_type)
-    return sys_type.lower()
+    if isinstance(d, basestring):
+        # We have an old spec using a string for the architecture
+        arch.platform = Platform('spack_compatibility')
+        arch.platform_os = OperatingSystem('unknown', '')
+        arch.target = Target(d)
+
+        arch.os_string = None
+        arch.target_string = None
+    else:
+        if d is None:
+            return None
+        platform_name = d['platform']
+        os_name = d['platform_os']
+        target_name = d['target']
+
+        if platform_name:
+            arch.platform = _platform_from_dict(platform_name)
+        else:
+            arch.platform = None
+        if target_name:
+            arch.target = _target_from_dict(target_name, arch.platform)
+        else:
+            arch.target = None
+        if os_name:
+            arch.platform_os = _operating_system_from_dict(os_name,
+                                                           arch.platform)
+        else:
+            arch.platform_os = None
+
+        arch.os_string = None
+        arch.target_string = None
+
+    return arch
 
 
 @memoized
-def sys_type():
-    """Returns a SysType for the current machine."""
-    methods = [get_sys_type_from_spack_globals, get_sys_type_from_environment,
-               get_sys_type_from_platform]
+def all_platforms():
+    classes = []
+    mod_path = spack.platform_path
+    parent_module = "spack.platforms"
+
+    for name in list_modules(mod_path):
+        mod_name = '%s.%s' % (parent_module, name)
+        class_name = mod_to_class(name)
+        mod = __import__(mod_name, fromlist=[class_name])
+        if not hasattr(mod, class_name):
+            tty.die('No class %s defined in %s' % (class_name, mod_name))
+        cls = getattr(mod, class_name)
+        if not inspect.isclass(cls):
+            tty.die('%s.%s is not a class' % (mod_name, class_name))
+
+        classes.append(cls)
 
-    # search for a method that doesn't return None
-    sys_type = None
-    for method in methods:
-        sys_type = method()
-        if sys_type:
-            break
+    return classes
 
-    # Couldn't determine the sys_type for this machine.
-    if sys_type is None:
-        return "unknown_arch"
 
-    if not isinstance(sys_type, basestring):
-        raise InvalidSysTypeError(sys_type)
+@memoized
+def sys_type():
+    """ Gather a list of all available subclasses of platforms.
+        Sorts the list according to their priority looking. Priority is
+        an arbitrarily set number. Detects platform either using uname or
+        a file path (/opt/cray...)
+    """
+    # Try to create a Platform object using the config file FIRST
+    platform_list = all_platforms()
+    platform_list.sort(key=lambda a: a.priority)
 
-    return sys_type
+    for platform in platform_list:
+        if platform.detect():
+            return platform()
diff --git a/lib/spack/spack/build_environment.py b/lib/spack/spack/build_environment.py
index d87aaa6285..7c65091d49 100644
--- a/lib/spack/spack/build_environment.py
+++ b/lib/spack/spack/build_environment.py
@@ -113,9 +113,66 @@ class MakeExecutable(Executable):
 
         return super(MakeExecutable, self).__call__(*args, **kwargs)
 
+def load_module(mod):
+    """Takes a module name and removes modules until it is possible to
+    load that module. It then loads the provided module. Depends on the
+    modulecmd implementation of modules used in cray and lmod.
+    """
+    #Create an executable of the module command that will output python code
+    modulecmd = which('modulecmd')
+    modulecmd.add_default_arg('python')
+
+    # Read the module and remove any conflicting modules
+    # We do this without checking that they are already installed
+    # for ease of programming because unloading a module that is not
+    # loaded does nothing.
+    text = modulecmd('show', mod, output=str, error=str).split()
+    for i, word in enumerate(text):
+        if word == 'conflict':
+            exec(compile(modulecmd('unload', text[i+1], output=str, error=str), '<string>', 'exec'))
+    # Load the module now that there are no conflicts
+    load = modulecmd('load', mod, output=str, error=str)
+    exec(compile(load, '<string>', 'exec'))
+
+def get_path_from_module(mod):
+    """Inspects a TCL module for entries that indicate the absolute path
+    at which the library supported by said module can be found.
+    """
+    # Create a modulecmd executable
+    modulecmd = which('modulecmd')
+    modulecmd.add_default_arg('python')
+
+    # Read the module
+    text = modulecmd('show', mod, output=str, error=str).split('\n')
+    # If it lists its package directory, return that
+    for line in text:
+        if line.find(mod.upper()+'_DIR') >= 0:
+            words = line.split()
+            return words[2]
+
+    # If it lists a -rpath instruction, use that
+    for line in text:
+        rpath = line.find('-rpath/')
+        if rpath >= 0:
+            return line[rpath+6:line.find('/lib')]
+
+    # If it lists a -L instruction, use that
+    for line in text:
+        L = line.find('-L/')
+        if L >= 0:
+            return line[L+2:line.find('/lib')]
+
+    # If it sets the LD_LIBRARY_PATH or CRAY_LD_LIBRARY_PATH, use that
+    for line in text:
+        if line.find('LD_LIBRARY_PATH') >= 0: 
+            words = line.split()
+            path = words[2]
+            return path[:path.find('/lib')]
+    # Unable to find module path
+    return None
 
 def set_compiler_environment_variables(pkg, env):
-    assert pkg.spec.concrete
+    assert(pkg.spec.concrete)
     compiler = pkg.compiler
     flags = pkg.spec.compiler_flags
 
@@ -154,6 +211,10 @@ def set_compiler_environment_variables(pkg, env):
             env.set('SPACK_' + flag.upper(), ' '.join(f for f in flags[flag]))
 
     env.set('SPACK_COMPILER_SPEC', str(pkg.spec.compiler))
+
+    for mod in compiler.modules:
+        load_module(mod)
+
     return env
 
 
@@ -212,13 +273,15 @@ def set_build_environment_variables(pkg, env):
     env.set(SPACK_DEBUG_LOG_DIR, spack.spack_working_dir)
 
     # Add any pkgconfig directories to PKG_CONFIG_PATH
-    pkg_config_dirs = []
-    for p in dep_prefixes:
-        for maybe in ('lib', 'lib64', 'share'):
-            pcdir = join_path(p, maybe, 'pkgconfig')
+    for pre in dep_prefixes:
+        for directory in ('lib', 'lib64', 'share'):
+            pcdir = join_path(pre, directory, 'pkgconfig')
             if os.path.isdir(pcdir):
-                pkg_config_dirs.append(pcdir)
-    env.set_path('PKG_CONFIG_PATH', pkg_config_dirs)
+                #pkg_config_dirs.append(pcdir)
+                env.prepend_path('PKG_CONFIG_PATH',pcdir)
+
+    if pkg.spec.architecture.target.module_name:
+        load_module(pkg.spec.architecture.target.module_name)
 
     return env
 
@@ -301,6 +364,10 @@ def get_rpaths(pkg):
                   if os.path.isdir(d.prefix.lib))
     rpaths.extend(d.prefix.lib64 for d in pkg.spec.dependencies.values()
                   if os.path.isdir(d.prefix.lib64))
+    # Second module is our compiler mod name. We use that to get rpaths from
+    # module show output. 
+    if pkg.compiler.modules and len(pkg.compiler.modules) > 1:
+        rpaths.append(get_path_from_module(pkg.compiler.modules[1]))
     return rpaths
 
 
@@ -317,6 +384,13 @@ def parent_class_modules(cls):
     return result
 
 
+def load_external_modules(pkg):
+    """ traverse the spec list and find any specs that have external modules.
+    """
+    for dep in list(pkg.spec.traverse()):
+        if dep.external_module:
+            load_module(dep.external_module)
+    
 def setup_package(pkg):
     """Execute all environment setup routines."""
     spack_env = EnvironmentModifications()
@@ -340,7 +414,7 @@ def setup_package(pkg):
 
     set_compiler_environment_variables(pkg, spack_env)
     set_build_environment_variables(pkg, spack_env)
-
+    load_external_modules(pkg)
     # traverse in postorder so package can use vars from its dependencies
     spec = pkg.spec
     for dspec in pkg.spec.traverse(order='post', root=False):
diff --git a/lib/spack/spack/cmd/arch.py b/lib/spack/spack/cmd/arch.py
index dc96dd0faa..cf2f96fd21 100644
--- a/lib/spack/spack/cmd/arch.py
+++ b/lib/spack/spack/cmd/arch.py
@@ -28,8 +28,4 @@ import spack.architecture as architecture
 description = "Print the architecture for this machine"
 
 def arch(parser, args):
-    configured_sys_type = architecture.get_sys_type_from_spack_globals()
-    if not configured_sys_type:
-        configured_sys_type = "autodetect"
-    print "Configured sys_type:             %s" % configured_sys_type
-    print "Autodetected default sys_type:   %s" % architecture.sys_type()
+    print architecture.sys_type()
diff --git a/lib/spack/spack/cmd/compiler.py b/lib/spack/spack/cmd/compiler.py
index dc7731a290..c95045ef85 100644
--- a/lib/spack/spack/cmd/compiler.py
+++ b/lib/spack/spack/cmd/compiler.py
@@ -70,7 +70,7 @@ def setup_parser(subparser):
 
 
 def compiler_find(args):
-    """Search either $PATH or a list of paths for compilers and add them
+    """Search either $PATH or a list of paths OR MODULES for compilers and add them
        to Spack's configuration."""
     paths = args.add_paths
     if not paths:
@@ -78,7 +78,6 @@ def compiler_find(args):
 
     compilers = [c for c in spack.compilers.find_compilers(*args.add_paths)
                  if c.spec not in spack.compilers.all_compilers(scope=args.scope)]
-
     if compilers:
         spack.compilers.add_compilers_to_config(compilers, scope=args.scope)
         n = len(compilers)
@@ -93,7 +92,6 @@ def compiler_find(args):
 def compiler_remove(args):
     cspec = CompilerSpec(args.compiler_spec)
     compilers = spack.compilers.compilers_for_spec(cspec, scope=args.scope)
-
     if not compilers:
         tty.die("No compilers match spec %s" % cspec)
     elif not args.all and len(compilers) > 1:
@@ -121,6 +119,8 @@ def compiler_info(args):
             print "\tcxx = %s" % c.cxx
             print "\tf77 = %s" % c.f77
             print "\tfc  = %s" % c.fc
+            print "\tmodules  = %s" % c.modules
+            print "\toperating system  = %s" % c.operating_system
 
 
 def compiler_list(args):
@@ -135,10 +135,10 @@ def compiler_list(args):
 
 
 def compiler(parser, args):
-    action = { 'add'    : compiler_find,
-               'find'   : compiler_find,
-               'remove' : compiler_remove,
-               'rm'     : compiler_remove,
-               'info'   : compiler_info,
-               'list'   : compiler_list }
+    action = {'add'    : compiler_find, 
+              'find'   : compiler_find,
+              'remove' : compiler_remove,
+              'rm'     : compiler_remove,
+              'info'   : compiler_info,
+              'list'   : compiler_list }
     action[args.compiler_command](args)
diff --git a/lib/spack/spack/cmd/find.py b/lib/spack/spack/cmd/find.py
index c22268d534..3ec671f93f 100644
--- a/lib/spack/spack/cmd/find.py
+++ b/lib/spack/spack/cmd/find.py
@@ -31,6 +31,7 @@ import spack.spec
 from llnl.util.lang import *
 from llnl.util.tty.colify import *
 from llnl.util.tty.color import *
+from llnl.util.lang import *
 
 description = "Find installed spack packages"
 
@@ -85,6 +86,11 @@ def setup_parser(subparser):
         action='store_true',
         dest='missing',
         help='Show missing dependencies as well as installed specs.')
+    subparser.add_argument(
+        '-v', '--variants',
+        action='store_true',
+        dest='variants',
+        help='Show variants in output (can be long)')
     subparser.add_argument('-M', '--only-missing',
                            action='store_true',
                            dest='only_missing',
@@ -106,6 +112,8 @@ def display_specs(specs, **kwargs):
     mode = kwargs.get('mode', 'short')
     hashes = kwargs.get('long', False)
     namespace = kwargs.get('namespace', False)
+    flags = kwargs.get('show_flags', False)
+    variants = kwargs.get('variants', False)
 
     hlen = 7
     if kwargs.get('very_long', False):
@@ -113,10 +121,9 @@ def display_specs(specs, **kwargs):
         hlen = None
 
     nfmt = '.' if namespace else '_'
-    format_string = '$%s$@$+' % nfmt
-    flags = kwargs.get('show_flags', False)
-    if flags:
-        format_string = '$%s$@$%%+$+' % nfmt
+    ffmt = '$%+' if flags else ''
+    vfmt = '$+' if variants else ''
+    format_string = '$%s$@%s%s' % (nfmt, ffmt, vfmt)
 
     # Make a dict with specs keyed by architecture and compiler.
     index = index_by(specs, ('architecture', 'compiler'))
@@ -162,7 +169,7 @@ def display_specs(specs, **kwargs):
                     string = ""
                     if hashes:
                         string += gray_hash(s, hlen) + ' '
-                    string += s.format('$-%s$@$+' % nfmt, color=True)
+                    string += s.format('$-%s$@%s' % (nfmt, vfmt), color=True)
 
                     return string
 
@@ -180,6 +187,29 @@ def display_specs(specs, **kwargs):
                 "deps, short)." % mode)  # NOQA: ignore=E501
 
 
+def query_arguments(args):
+    # Check arguments
+    if args.explicit and args.implicit:
+        tty.error('You can\'t pass -E and -e options simultaneously.')
+        raise SystemExit(1)
+
+    # Set up query arguments.
+    installed, known = True, any
+    if args.only_missing:
+        installed = False
+    elif args.missing:
+        installed = any
+    if args.unknown:
+        known = False
+    explicit = any
+    if args.explicit:
+        explicit = True
+    if args.implicit:
+        explicit = False
+    q_args = {'installed': installed, 'known': known, "explicit": explicit}
+    return q_args
+
+
 def find(parser, args):
     # Filter out specs that don't exist.
     query_specs = spack.cmd.parse_specs(args.query_specs)
@@ -194,22 +224,7 @@ def find(parser, args):
         if not query_specs:
             return
 
-    # Set up query arguments.
-    installed, known = True, any
-    if args.only_missing:
-        installed = False
-    elif args.missing:
-        installed = any
-    if args.unknown:
-        known = False
-
-    explicit = any
-    if args.explicit:
-        explicit = False
-    if args.implicit:
-        explicit = True
-
-    q_args = {'installed': installed, 'known': known, "explicit": explicit}
+    q_args = query_arguments(args)
 
     # Get all the specs the user asked for
     if not query_specs:
@@ -228,4 +243,6 @@ def find(parser, args):
                   mode=args.mode,
                   long=args.long,
                   very_long=args.very_long,
-                  show_flags=args.show_flags)
+                  show_flags=args.show_flags,
+                  namespace=args.namespace,
+                  variants=args.variants)
diff --git a/lib/spack/spack/cmd/uninstall.py b/lib/spack/spack/cmd/uninstall.py
index 9fdf3045b2..a6f08d09ed 100644
--- a/lib/spack/spack/cmd/uninstall.py
+++ b/lib/spack/spack/cmd/uninstall.py
@@ -39,6 +39,13 @@ error_message = """You can either:
     b) use spack uninstall -a to uninstall ALL matching specs.
 """
 
+# Arguments for display_specs when we find ambiguity
+display_args = {
+    'long': True,
+    'show_flags': True,
+    'variants':True
+}
+
 
 def ask_for_confirmation(message):
     while True:
@@ -92,7 +99,7 @@ def concretize_specs(specs, allow_multiple_matches=False, force=False):
         if not allow_multiple_matches and len(matching) > 1:
             tty.error("%s matches multiple packages:" % spec)
             print()
-            display_specs(matching, long=True, show_flags=True)
+            display_specs(matching, **display_args)
             print()
             has_errors = True
 
@@ -172,7 +179,7 @@ def uninstall(parser, args):
                 tty.error("Will not uninstall %s" % spec.format("$_$@$%@$#", color=True))
                 print('')
                 print("The following packages depend on it:")
-                display_specs(lst, long=True)
+                display_specs(lst, **display_args)
                 print('')
                 has_error = True
         elif args.dependents:
@@ -186,7 +193,7 @@ def uninstall(parser, args):
         if not args.yes_to_all:
             tty.msg("The following packages will be uninstalled : ")
             print('')
-            display_specs(uninstall_list, long=True, show_flags=True)
+            display_specs(uninstall_list, **display_args)
             print('')
             ask_for_confirmation('Do you want to proceed ? ')
 
diff --git a/lib/spack/spack/cmd/view.py b/lib/spack/spack/cmd/view.py
new file mode 100644
index 0000000000..8f1fc9be74
--- /dev/null
+++ b/lib/spack/spack/cmd/view.py
@@ -0,0 +1,295 @@
+##############################################################################
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://github.com/llnl/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License (as published by
+# the Free Software Foundation) version 2.1 dated February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+'''Produce a "view" of a Spack DAG.
+
+A "view" is file hierarchy representing the union of a number of
+Spack-installed package file hierarchies.  The union is formed from:
+
+- specs resolved from the package names given by the user (the seeds)
+
+- all depenencies of the seeds unless user specifies `--no-depenencies`
+
+- less any specs with names matching the regular expressions given by
+  `--exclude`
+
+The `view` can be built and tore down via a number of methods (the "actions"):
+
+- symlink :: a file system view which is a directory hierarchy that is
+  the union of the hierarchies of the installed packages in the DAG
+  where installed files are referenced via symlinks.
+
+- hardlink :: like the symlink view but hardlinks are used.
+
+- statlink :: a view producing a status report of a symlink or
+  hardlink view.
+
+The file system view concept is imspired by Nix, implemented by
+brett.viren@gmail.com ca 2016.
+
+'''
+# Implementation notes:
+#
+# This is implemented as a visitor pattern on the set of package specs.
+#
+# The command line ACTION maps to a visitor_*() function which takes
+# the set of package specs and any args which may be specific to the
+# ACTION.
+#
+# To add a new view:
+# 1. add a new cmd line args sub parser ACTION
+# 2. add any action-specific options/arguments, most likely a list of specs.
+# 3. add a visitor_MYACTION() function
+# 4. add any visitor_MYALIAS assignments to match any command line aliases
+
+import os
+import re
+import spack
+import spack.cmd
+import llnl.util.tty as tty
+
+description = "Produce a single-rooted directory view of a spec."
+
+
+def setup_parser(sp):
+    setup_parser.parser = sp
+
+    sp.add_argument(
+        '-v', '--verbose', action='store_true', default=False,
+        help="Display verbose output.")
+    sp.add_argument(
+        '-e', '--exclude', action='append', default=[],
+        help="Exclude packages with names matching the given regex pattern.")
+    sp.add_argument(
+        '-d', '--dependencies', choices=['true', 'false', 'yes', 'no'],
+        default='true',
+        help="Follow dependencies.")
+
+    ssp = sp.add_subparsers(metavar='ACTION', dest='action')
+
+    specs_opts = dict(metavar='spec', nargs='+',
+                      help="Seed specs of the packages to view.")
+
+    # The action parameterizes the command but in keeping with Spack
+    # patterns we make it a subcommand.
+    file_system_view_actions = [
+        ssp.add_parser(
+            'symlink', aliases=['add', 'soft'],
+            help='Add package files to a filesystem view via symbolic links.'),
+        ssp.add_parser(
+            'hardlink', aliases=['hard'],
+            help='Add packages files to a filesystem via via hard links.'),
+        ssp.add_parser(
+            'remove', aliases=['rm'],
+            help='Remove packages from a filesystem view.'),
+        ssp.add_parser(
+            'statlink', aliases=['status', 'check'],
+            help='Check status of packages in a filesystem view.')
+    ]
+    # All these options and arguments are common to every action.
+    for act in file_system_view_actions:
+        act.add_argument('path', nargs=1,
+                         help="Path to file system view directory.")
+        act.add_argument('specs', **specs_opts)
+
+    return
+
+
+def assuredir(path):
+    'Assure path exists as a directory'
+    if not os.path.exists(path):
+        os.makedirs(path)
+
+
+def relative_to(prefix, path):
+    'Return end of `path` relative to `prefix`'
+    assert 0 == path.find(prefix)
+    reldir = path[len(prefix):]
+    if reldir.startswith('/'):
+        reldir = reldir[1:]
+    return reldir
+
+
+def transform_path(spec, path, prefix=None):
+    'Return the a relative path corresponding to given path spec.prefix'
+    if os.path.isabs(path):
+        path = relative_to(spec.prefix, path)
+    subdirs = path.split(os.path.sep)
+    if subdirs[0] == '.spack':
+        lst = ['.spack', spec.name] + subdirs[1:]
+        path = os.path.join(*lst)
+    if prefix:
+        path = os.path.join(prefix, path)
+    return path
+
+
+def purge_empty_directories(path):
+    '''Ascend up from the leaves accessible from `path`
+    and remove empty directories.'''
+    for dirpath, subdirs, files in os.walk(path, topdown=False):
+        for sd in subdirs:
+            sdp = os.path.join(dirpath, sd)
+            try:
+                os.rmdir(sdp)
+            except OSError:
+                pass
+
+
+def filter_exclude(specs, exclude):
+    'Filter specs given sequence of exclude regex'
+    to_exclude = [re.compile(e) for e in exclude]
+
+    def exclude(spec):
+        for e in to_exclude:
+            if e.match(spec.name):
+                return True
+        return False
+    return [s for s in specs if not exclude(s)]
+
+
+def flatten(seeds, descend=True):
+    'Normalize and flattend seed specs and descend hiearchy'
+    flat = set()
+    for spec in seeds:
+        if not descend:
+            flat.add(spec)
+            continue
+        flat.update(spec.normalized().traverse())
+    return flat
+
+
+def check_one(spec, path, verbose=False):
+    'Check status of view in path against spec'
+    dotspack = os.path.join(path, '.spack', spec.name)
+    if os.path.exists(os.path.join(dotspack)):
+        tty.info('Package in view: "%s"' % spec.name)
+        return
+    tty.info('Package not in view: "%s"' % spec.name)
+    return
+
+
+def remove_one(spec, path, verbose=False):
+    'Remove any files found in `spec` from `path` and purge empty directories.'
+
+    if not os.path.exists(path):
+        return                  # done, short circuit
+
+    dotspack = transform_path(spec, '.spack', path)
+    if not os.path.exists(dotspack):
+        if verbose:
+            tty.info('Skipping nonexistent package: "%s"' % spec.name)
+        return
+
+    if verbose:
+        tty.info('Removing package: "%s"' % spec.name)
+    for dirpath, dirnames, filenames in os.walk(spec.prefix):
+        if not filenames:
+            continue
+        targdir = transform_path(spec, dirpath, path)
+        for fname in filenames:
+            dst = os.path.join(targdir, fname)
+            if not os.path.exists(dst):
+                continue
+            os.unlink(dst)
+
+
+def link_one(spec, path, link=os.symlink, verbose=False):
+    'Link all files in `spec` into directory `path`.'
+
+    dotspack = transform_path(spec, '.spack', path)
+    if os.path.exists(dotspack):
+        tty.warn('Skipping existing package: "%s"' % spec.name)
+        return
+
+    if verbose:
+        tty.info('Linking package: "%s"' % spec.name)
+    for dirpath, dirnames, filenames in os.walk(spec.prefix):
+        if not filenames:
+            continue        # avoid explicitly making empty dirs
+
+        targdir = transform_path(spec, dirpath, path)
+        assuredir(targdir)
+
+        for fname in filenames:
+            src = os.path.join(dirpath, fname)
+            dst = os.path.join(targdir, fname)
+            if os.path.exists(dst):
+                if '.spack' in dst.split(os.path.sep):
+                    continue    # silence these
+                tty.warn("Skipping existing file: %s" % dst)
+                continue
+            link(src, dst)
+
+
+def visitor_symlink(specs, args):
+    'Symlink all files found in specs'
+    path = args.path[0]
+    assuredir(path)
+    for spec in specs:
+        link_one(spec, path, verbose=args.verbose)
+visitor_add = visitor_symlink
+visitor_soft = visitor_symlink
+
+
+def visitor_hardlink(specs, args):
+    'Hardlink all files found in specs'
+    path = args.path[0]
+    assuredir(path)
+    for spec in specs:
+        link_one(spec, path, os.link, verbose=args.verbose)
+visitor_hard = visitor_hardlink
+
+
+def visitor_remove(specs, args):
+    'Remove all files and directories found in specs from args.path'
+    path = args.path[0]
+    for spec in specs:
+        remove_one(spec, path, verbose=args.verbose)
+    purge_empty_directories(path)
+visitor_rm = visitor_remove
+
+
+def visitor_statlink(specs, args):
+    'Give status of view in args.path relative to specs'
+    path = args.path[0]
+    for spec in specs:
+        check_one(spec, path, verbose=args.verbose)
+visitor_status = visitor_statlink
+visitor_check = visitor_statlink
+
+
+def view(parser, args):
+    'Produce a view of a set of packages.'
+
+    # Process common args
+    seeds = [spack.cmd.disambiguate_spec(s) for s in args.specs]
+    specs = flatten(seeds, args.dependencies.lower() in ['yes', 'true'])
+    specs = filter_exclude(specs, args.exclude)
+
+    # Execute the visitation.
+    try:
+        visitor = globals()['visitor_' + args.action]
+    except KeyError:
+        tty.error('Unknown action: "%s"' % args.action)
+    visitor(specs, args)
diff --git a/lib/spack/spack/compiler.py b/lib/spack/spack/compiler.py
index 2ae305f201..ce4555bc56 100644
--- a/lib/spack/spack/compiler.py
+++ b/lib/spack/spack/compiler.py
@@ -33,6 +33,7 @@ from llnl.util.filesystem import join_path
 
 import spack.error
 import spack.spec
+import spack.architecture
 from spack.util.multiproc import parmap
 from spack.util.executable import *
 from spack.util.environment import get_path
@@ -107,19 +108,32 @@ class Compiler(object):
     @property
     def fc_rpath_arg(self):
         return '-Wl,-rpath,'
+    # Cray PrgEnv name that can be used to load this compiler
+    PrgEnv = None
+    # Name of module used to switch versions of this compiler
+    PrgEnv_compiler = None
 
-
-    def __init__(self, cspec, cc, cxx, f77, fc, **kwargs):
+    def __init__(self, cspec, operating_system, 
+                 paths, modules=[], alias=None, **kwargs):
         def check(exe):
             if exe is None:
                 return None
             _verify_executables(exe)
             return exe
 
-        self.cc  = check(cc)
-        self.cxx = check(cxx)
-        self.f77 = check(f77)
-        self.fc  = check(fc)
+        self.cc  = check(paths[0])
+        self.cxx = check(paths[1])
+        if len(paths) > 2:
+            self.f77 = check(paths[2])
+            if len(paths) == 3:
+                self.fc = self.f77
+            else:
+                self.fc  = check(paths[3])
+
+        #self.cc  = check(cc)
+        #self.cxx = check(cxx)
+        #self.f77 = check(f77)
+        #self.fc  = check(fc)
 
         # Unfortunately have to make sure these params are accepted
         # in the same order they are returned by sorted(flags)
@@ -130,8 +144,10 @@ class Compiler(object):
             if value is not None:
                 self.flags[flag] = value.split()
 
+        self.operating_system = operating_system
         self.spec = cspec
-
+        self.modules = modules
+        self.alias = alias
 
     @property
     def version(self):
@@ -258,57 +274,6 @@ class Compiler(object):
         successful.reverse()
         return dict(((v, p, s), path) for v, p, s, path in successful)
 
-    @classmethod
-    def find(cls, *path):
-        """Try to find this type of compiler in the user's
-           environment. For each set of compilers found, this returns
-           compiler objects with the cc, cxx, f77, fc paths and the
-           version filled in.
-
-           This will search for compilers with the names in cc_names,
-           cxx_names, etc. and it will group them if they have common
-           prefixes, suffixes, and versions.  e.g., gcc-mp-4.7 would
-           be grouped with g++-mp-4.7 and gfortran-mp-4.7.
-        """
-        dicts = parmap(
-            lambda t: cls._find_matches_in_path(*t),
-            [(cls.cc_names,  cls.cc_version)  + tuple(path),
-             (cls.cxx_names, cls.cxx_version) + tuple(path),
-             (cls.f77_names, cls.f77_version) + tuple(path),
-             (cls.fc_names,  cls.fc_version)  + tuple(path)])
-
-        all_keys = set()
-        for d in dicts:
-            all_keys.update(d)
-
-        compilers = {}
-        for k in all_keys:
-            ver, pre, suf = k
-
-            # Skip compilers with unknown version.
-            if ver == 'unknown':
-                continue
-
-            paths = tuple(pn[k] if k in pn else None for pn in dicts)
-            spec = spack.spec.CompilerSpec(cls.name, ver)
-
-            if ver in compilers:
-                prev = compilers[ver]
-
-                # prefer the one with more compilers.
-                prev_paths = [prev.cc, prev.cxx, prev.f77, prev.fc]
-                newcount  = len([p for p in paths      if p is not None])
-                prevcount = len([p for p in prev_paths if p is not None])
-
-                # Don't add if it's not an improvement over prev compiler.
-                if newcount <= prevcount:
-                    continue
-
-            compilers[ver] = cls(spec, *paths)
-
-        return list(compilers.values())
-
-
     def __repr__(self):
         """Return a string representation of the compiler toolchain."""
         return self.__str__()
@@ -317,7 +282,7 @@ class Compiler(object):
     def __str__(self):
         """Return a string representation of the compiler toolchain."""
         return "%s(%s)" % (
-            self.name, '\n     '.join((str(s) for s in (self.cc, self.cxx, self.f77, self.fc))))
+            self.name, '\n     '.join((str(s) for s in (self.cc, self.cxx, self.f77, self.fc, self.modules, str(self.operating_system)))))
 
 
 class CompilerAccessError(spack.error.SpackError):
diff --git a/lib/spack/spack/compilers/__init__.py b/lib/spack/spack/compilers/__init__.py
index 7c951ae8bc..ae72b743b2 100644
--- a/lib/spack/spack/compilers/__init__.py
+++ b/lib/spack/spack/compilers/__init__.py
@@ -28,6 +28,11 @@ system and configuring Spack to use multiple compilers.
 import imp
 import os
 import platform
+import copy
+import hashlib
+import base64
+import yaml
+import sys
 
 from llnl.util.lang import memoized, list_modules
 from llnl.util.filesystem import join_path
@@ -45,7 +50,9 @@ from spack.util.naming import mod_to_class
 from spack.util.environment import get_path
 
 _imported_compilers_module = 'spack.compilers'
-_required_instance_vars = ['cc', 'cxx', 'f77', 'fc']
+_path_instance_vars = ['cc', 'cxx', 'f77', 'fc']
+_other_instance_vars = ['modules', 'operating_system']
+_cache_config_file = []
 
 # TODO: customize order in config file
 if platform.system() == 'Darwin':
@@ -64,107 +71,105 @@ def _auto_compiler_spec(function):
 
 def _to_dict(compiler):
     """Return a dict version of compiler suitable to insert in YAML."""
-    return {
-        str(compiler.spec) : dict(
-            (attr, getattr(compiler, attr, None))
-            for attr in _required_instance_vars)
-    }
+    d = {}
+    d['spec'] = str(compiler.spec)
+    d['paths'] = dict( (attr, getattr(compiler, attr, None)) for attr in _path_instance_vars )
+    d['operating_system'] = str(compiler.operating_system)
+    d['modules'] = compiler.modules if compiler.modules else []
 
+    if compiler.alias:
+        d['alias'] = compiler.alias
 
-def get_compiler_config(arch=None, scope=None):
+    return {'compiler': d}
+
+
+def get_compiler_config(scope=None):
     """Return the compiler configuration for the specified architecture.
     """
-    # Check whether we're on a front-end (native) architecture.
-    my_arch = spack.architecture.sys_type()
-    if arch is None:
-        arch = my_arch
-
     def init_compiler_config():
         """Compiler search used when Spack has no compilers."""
-        config[arch] = {}
-        compilers = find_compilers(*get_path('PATH'))
+        compilers = find_compilers()
+        compilers_dict = []
         for compiler in compilers:
-            config[arch].update(_to_dict(compiler))
-        spack.config.update_config('compilers', config, scope=scope)
+            compilers_dict.append(_to_dict(compiler))
+        spack.config.update_config('compilers', compilers_dict, scope=scope)
 
     config = spack.config.get_config('compilers', scope=scope)
-
     # Update the configuration if there are currently no compilers
     # configured.  Avoid updating automatically if there ARE site
     # compilers configured but no user ones.
-    if arch == my_arch and arch not in config:
+    if not config:
         if scope is None:
             # We know no compilers were configured in any scope.
             init_compiler_config()
+            config = spack.config.get_config('compilers', scope=scope)
         elif scope == 'user':
             # Check the site config and update the user config if
             # nothing is configured at the site level.
             site_config = spack.config.get_config('compilers', scope='site')
             if not site_config:
                 init_compiler_config()
-
-    return config[arch] if arch in config else {}
+                config = spack.config.get_config('compilers', scope=scope)
+        return config
+    elif config:
+        return config
+    else:
+        return []  # Return empty list which we will later append to.
 
 
-def add_compilers_to_config(compilers, arch=None, scope=None):
+def add_compilers_to_config(compilers, scope=None):
     """Add compilers to the config for the specified architecture.
 
     Arguments:
       - compilers: a list of Compiler objects.
-      - arch:      arch to add compilers for.
       - scope:     configuration scope to modify.
     """
-    if arch is None:
-        arch = spack.architecture.sys_type()
-
-    compiler_config = get_compiler_config(arch, scope)
+    compiler_config = get_compiler_config(scope)
     for compiler in compilers:
-        compiler_config[str(compiler.spec)] = dict(
-            (c, getattr(compiler, c, "None"))
-            for c in _required_instance_vars)
-
-    update = { arch : compiler_config }
-    spack.config.update_config('compilers', update, scope)
+        compiler_config.append(_to_dict(compiler))
+    global _cache_config_file
+    _cache_config_file = compiler_config
+    spack.config.update_config('compilers', compiler_config, scope)
 
 
 @_auto_compiler_spec
-def remove_compiler_from_config(compiler_spec, arch=None, scope=None):
+def remove_compiler_from_config(compiler_spec, scope=None):
     """Remove compilers from the config, by spec.
 
     Arguments:
       - compiler_specs: a list of CompilerSpec objects.
-      - arch:           arch to add compilers for.
       - scope:          configuration scope to modify.
     """
-    if arch is None:
-        arch = spack.architecture.sys_type()
-
-    compiler_config = get_compiler_config(arch, scope)
-    del compiler_config[str(compiler_spec)]
-    update = { arch : compiler_config }
-
-    spack.config.update_config('compilers', update, scope)
-
-
-def all_compilers_config(arch=None, scope=None):
+    compiler_config = get_compiler_config(scope)
+    config_length = len(compiler_config)
+    
+    filtered_compiler_config = [comp for comp in compiler_config 
+               if spack.spec.CompilerSpec(comp['compiler']['spec']) != compiler_spec]
+    # Need a better way for this
+    global _cache_config_file
+    _cache_config_file = filtered_compiler_config # Update the cache for changes
+    if len(filtered_compiler_config) == config_length: # No items removed
+        CompilerSpecInsufficientlySpecificError(compiler_spec)
+    spack.config.update_config('compilers', filtered_compiler_config, scope)
+
+
+def all_compilers_config(scope=None):
     """Return a set of specs for all the compiler versions currently
        available to build with.  These are instances of CompilerSpec.
     """
     # Get compilers for this architecture.
-    arch_config = get_compiler_config(arch, scope)
-
-    # Merge 'all' compilers with arch-specific ones.
-    # Arch-specific compilers have higher precedence.
-    merged_config = get_compiler_config('all', scope=scope)
-    merged_config = spack.config._merge_yaml(merged_config, arch_config)
-
-    return merged_config
+    global _cache_config_file #Create a cache of the config file so we don't load all the time.
+    if not _cache_config_file:
+        _cache_config_file = get_compiler_config(scope)
+        return _cache_config_file
+    else:
+        return _cache_config_file
 
 
-def all_compilers(arch=None, scope=None):
+def all_compilers(scope=None):
     # Return compiler specs from the merged config.
-    return [spack.spec.CompilerSpec(s)
-            for s in all_compilers_config(arch, scope)]
+    return [spack.spec.CompilerSpec(s['compiler']['spec'])
+            for s in all_compilers_config(scope)]
 
 
 def default_compiler():
@@ -179,36 +184,18 @@ def default_compiler():
     return sorted(versions)[-1]
 
 
-def find_compilers(*path):
+def find_compilers(*paths):
     """Return a list of compilers found in the suppied paths.
-       This invokes the find() method for each Compiler class,
-       and appends the compilers detected to a list.
+       This invokes the find_compilers() method for each operating
+       system associated with the host platform, and appends
+       the compilers detected to a list.
     """
-    # Make sure path elements exist, and include /bin directories
-    # under prefixes.
-    filtered_path = []
-    for p in path:
-        # Eliminate symlinks and just take the real directories.
-        p = os.path.realpath(p)
-        if not os.path.isdir(p):
-            continue
-        filtered_path.append(p)
-
-        # Check for a bin directory, add it if it exists
-        bin = join_path(p, 'bin')
-        if os.path.isdir(bin):
-            filtered_path.append(os.path.realpath(bin))
-
-    # Once the paths are cleaned up, do a search for each type of
-    # compiler.  We can spawn a bunch of parallel searches to reduce
-    # the overhead of spelunking all these directories.
-    types = all_compiler_types()
-    compiler_lists = parmap(lambda cls: cls.find(*filtered_path), types)
-
-    # ensure all the version calls we made are cached in the parent
-    # process, as well.  This speeds up Spack a lot.
-    clist = reduce(lambda x,y: x+y, compiler_lists)
-    return clist
+    # Find compilers for each operating system class
+    oss = all_os_classes()
+    compiler_lists = []
+    for o in oss:
+        compiler_lists.extend(o.find_compilers(*paths))
+    return compiler_lists
 
 
 def supported_compilers():
@@ -227,51 +214,83 @@ def supported(compiler_spec):
 
 
 @_auto_compiler_spec
-def find(compiler_spec, arch=None, scope=None):
+def find(compiler_spec, scope=None):
     """Return specs of available compilers that match the supplied
        compiler spec.  Return an list if nothing found."""
-    return [c for c in all_compilers(arch, scope) if c.satisfies(compiler_spec)]
+    return [c for c in all_compilers(scope) if c.satisfies(compiler_spec)]
 
 
 @_auto_compiler_spec
-def compilers_for_spec(compiler_spec, arch=None, scope=None):
+def compilers_for_spec(compiler_spec, scope=None, **kwargs):
     """This gets all compilers that satisfy the supplied CompilerSpec.
        Returns an empty list if none are found.
     """
-    config = all_compilers_config(arch, scope)
+    platform = kwargs.get("platform", None)
+    config = all_compilers_config(scope)
+
+    def get_compilers(cspec):
+        compilers = []
 
-    def get_compiler(cspec):
-        items = config[str(cspec)]
+        for items in config:
+            if items['compiler']['spec'] != str(cspec):
+                continue
+            items = items['compiler']
 
-        if not all(n in items for n in _required_instance_vars):
-            raise InvalidCompilerConfigurationError(cspec)
+            if not ('paths' in items and all(n in items['paths'] for n in _path_instance_vars)):
+                raise InvalidCompilerConfigurationError(cspec)
 
-        cls  = class_for_compiler_name(cspec.name)
-        compiler_paths = []
-        for c in _required_instance_vars:
-            compiler_path = items[c]
-            if compiler_path != "None":
-                compiler_paths.append(compiler_path)
+            cls  = class_for_compiler_name(cspec.name)
+
+            compiler_paths = []
+            for c in _path_instance_vars:
+                compiler_path = items['paths'][c]
+                if compiler_path != "None":
+                    compiler_paths.append(compiler_path)
+                else:
+                    compiler_paths.append(None)
+
+            mods = items.get('modules')
+            if mods == 'None':
+                mods = []
+
+            if 'operating_system' in items:
+                operating_system = spack.architecture._operating_system_from_dict(items['operating_system'], platform)
             else:
-                compiler_paths.append(None)
+                operating_system = None
+
 
-        flags = {}
-        for f in spack.spec.FlagMap.valid_compiler_flags():
-            if f in items:
-                flags[f] = items[f]
-        return cls(cspec, *compiler_paths, **flags)
+            alias = items['alias'] if 'alias' in items else None
 
-    matches = find(compiler_spec, arch, scope)
-    return [get_compiler(cspec) for cspec in matches]
+            flags = {}
+            for f in spack.spec.FlagMap.valid_compiler_flags():
+                if f in items:
+                    flags[f] = items[f]
+
+            compilers.append(cls(cspec, operating_system, compiler_paths, mods, alias, **flags))
+
+        return compilers
+
+    matches = set(find(compiler_spec, scope))
+    compilers = []
+    for cspec in matches:
+        compilers.extend(get_compilers(cspec))
+    return compilers
+#    return [get_compilers(cspec) for cspec in matches]
 
 
 @_auto_compiler_spec
-def compiler_for_spec(compiler_spec):
+def compiler_for_spec(compiler_spec, arch):
     """Get the compiler that satisfies compiler_spec.  compiler_spec must
        be concrete."""
+    operating_system = arch.platform_os
     assert(compiler_spec.concrete)
-    compilers = compilers_for_spec(compiler_spec)
-    assert(len(compilers) == 1)
+
+    compilers = [c for c in compilers_for_spec(compiler_spec, platform=arch.platform)
+                if c.operating_system == operating_system]
+    if len(compilers) < 1:
+        raise NoCompilerForSpecError(compiler_spec, operating_system)
+    if len(compilers) > 1:
+        raise CompilerSpecInsufficientlySpecificError(compiler_spec)
     return compilers[0]
 
 
@@ -289,6 +308,19 @@ def class_for_compiler_name(compiler_name):
     return cls
 
 
+def all_os_classes():
+    """
+    Return the list of classes for all operating systems available on
+    this platform
+    """
+    classes = []
+
+    platform = spack.architecture.sys_type()
+    for os_class in platform.operating_sys.values():
+        classes.append(os_class)
+
+    return classes
+
 def all_compiler_types():
     return [class_for_compiler_name(c) for c in supported_compilers()]
 
@@ -298,9 +330,19 @@ class InvalidCompilerConfigurationError(spack.error.SpackError):
         super(InvalidCompilerConfigurationError, self).__init__(
             "Invalid configuration for [compiler \"%s\"]: " % compiler_spec,
             "Compiler configuration must contain entries for all compilers: %s"
-            % _required_instance_vars)
+            % _path_instance_vars)
 
 
 class NoCompilersError(spack.error.SpackError):
     def __init__(self):
         super(NoCompilersError, self).__init__("Spack could not find any compilers!")
+
+class NoCompilerForSpecError(spack.error.SpackError):
+    def __init__(self, compiler_spec, target):
+        super(NoCompilerForSpecError, self).__init__("No compilers for operating system %s satisfy spec %s" % (
+                                                     target, compiler_spec))
+
+class CompilerSpecInsufficientlySpecificError(spack.error.SpackError):
+    def __init__(self, compiler_spec):
+        super(CompilerSpecInsufficientlySpecificError, self).__init__("Multiple compilers satisfy spec %s",
+                                                                      compiler_spec)
diff --git a/lib/spack/spack/compilers/clang.py b/lib/spack/spack/compilers/clang.py
index 072bcd065f..00b406d820 100644
--- a/lib/spack/spack/compilers/clang.py
+++ b/lib/spack/spack/compilers/clang.py
@@ -73,7 +73,7 @@ class Clang(Compiler):
                 return "-std=c++11"
 
     @classmethod
-    def default_version(self, comp):
+    def default_version(cls, comp):
         """The '--version' option works for clang compilers.
            On most platforms, output looks like this::
 
diff --git a/lib/spack/spack/compilers/craype.py b/lib/spack/spack/compilers/craype.py
new file mode 100644
index 0000000000..4ba8b110ec
--- /dev/null
+++ b/lib/spack/spack/compilers/craype.py
@@ -0,0 +1,58 @@
+##############################################################################}
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License (as published by
+# the Free Software Foundation) version 2.1 dated February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+import llnl.util.tty as tty
+
+#from spack.build_environment import load_module
+from spack.compiler import *
+#from spack.version import ver
+
+class Craype(Compiler):
+    # Subclasses use possible names of C compiler
+    cc_names = ['cc']
+
+    # Subclasses use possible names of C++ compiler
+    cxx_names = ['CC']
+
+    # Subclasses use possible names of Fortran 77 compiler
+    f77_names = ['ftn']
+
+    # Subclasses use possible names of Fortran 90 compiler
+    fc_names = ['ftn']
+
+    # MacPorts builds gcc versions with prefixes and -mp-X.Y suffixes.
+    suffixes = [r'-mp-\d\.\d']
+
+    PrgEnv = 'PrgEnv-cray'
+    PrgEnv_compiler = 'craype'
+
+    link_paths = { 'cc'  : 'cc',
+                   'cxx' : 'c++',
+                   'f77' : 'f77',
+                   'fc'  : 'fc'}
+ 
+    @classmethod
+    def default_version(cls, comp):
+        return get_compiler_version(comp, r'([Vv]ersion).*(\d+(\.\d+)+)')
+
diff --git a/lib/spack/spack/compilers/gcc.py b/lib/spack/spack/compilers/gcc.py
index 164bddeb3f..3f552eaece 100644
--- a/lib/spack/spack/compilers/gcc.py
+++ b/lib/spack/spack/compilers/gcc.py
@@ -49,6 +49,9 @@ class Gcc(Compiler):
                   'f77' : 'gcc/gfortran',
                   'fc'  : 'gcc/gfortran' }
 
+    PrgEnv = 'PrgEnv-gnu'
+    PrgEnv_compiler = 'gcc'
+
     @property
     def openmp_flag(self):
         return "-fopenmp"
@@ -74,9 +77,9 @@ class Gcc(Compiler):
         return get_compiler_version(
             fc, '-dumpversion',
             # older gfortran versions don't have simple dumpversion output.
-            r'(?:GNU Fortran \(GCC\))?(\d+\.\d+(?:\.\d+)?)')
+            r'(?:GNU Fortran \(GCC\))?(\d+\.\d+(?:\.\d+)?)', module)
 
 
     @classmethod
     def f77_version(cls, f77):
-        return cls.fc_version(f77)
+        return cls.fc_version(f77, module)
diff --git a/lib/spack/spack/compilers/intel.py b/lib/spack/spack/compilers/intel.py
index 5007ece645..6cad03ff47 100644
--- a/lib/spack/spack/compilers/intel.py
+++ b/lib/spack/spack/compilers/intel.py
@@ -45,6 +45,9 @@ class Intel(Compiler):
                    'f77' : 'intel/ifort',
                    'fc'  : 'intel/ifort' }
 
+    PrgEnv = 'PrgEnv-intel'
+    PrgEnv_compiler = 'intel'
+
     @property
     def openmp_flag(self):
         if self.version < ver('16.0'):
diff --git a/lib/spack/spack/compilers/pgi.py b/lib/spack/spack/compilers/pgi.py
index d42148dc49..6d36d8bfa6 100644
--- a/lib/spack/spack/compilers/pgi.py
+++ b/lib/spack/spack/compilers/pgi.py
@@ -44,6 +44,12 @@ class Pgi(Compiler):
                    'f77' : 'pgi/pgfortran',
                    'fc'  : 'pgi/pgfortran' }
 
+
+
+    PrgEnv = 'PrgEnv-pgi'
+    PrgEnv_compiler = 'pgi'
+
+
     @property
     def openmp_flag(self):
         return "-mp"
@@ -52,7 +58,6 @@ class Pgi(Compiler):
     def cxx11_flag(self):
         return "-std=c++11"
 
-
     @classmethod
     def default_version(cls, comp):
         """The '-V' option works for all the PGI compilers.
diff --git a/lib/spack/spack/compilers/xl.py b/lib/spack/spack/compilers/xl.py
index bda2de4b87..b1431436ad 100644
--- a/lib/spack/spack/compilers/xl.py
+++ b/lib/spack/spack/compilers/xl.py
@@ -56,8 +56,9 @@ class Xl(Compiler):
         else:
             return "-qlanglvl=extended0x"
 
+
     @classmethod
-    def default_version(self, comp):
+    def default_version(cls, comp):
         """The '-qversion' is the standard option fo XL compilers.
            Output looks like this::
 
@@ -83,6 +84,7 @@ class Xl(Compiler):
         return get_compiler_version(
             comp, '-qversion',r'([0-9]?[0-9]\.[0-9])')
 
+
     @classmethod
     def fc_version(cls, fc):
         """The fortran and C/C++ versions of the XL compiler are always two units apart.
diff --git a/lib/spack/spack/concretize.py b/lib/spack/spack/concretize.py
index 4f78bfc347..1f37455c77 100644
--- a/lib/spack/spack/concretize.py
+++ b/lib/spack/spack/concretize.py
@@ -84,7 +84,8 @@ class DefaultConcretizer(object):
             raise NoBuildError(spec)
 
         def cmp_externals(a, b):
-            if a.name != b.name:
+            if a.name != b.name and (not a.external or a.external_module and
+                    not b.external and b.external_module):
                 # We're choosing between different providers, so
                 # maintain order from provider sort
                 return candidates.index(a) - candidates.index(b)
@@ -187,31 +188,64 @@ class DefaultConcretizer(object):
 
         return True   # Things changed
 
+    def _concretize_operating_system(self, spec):
+        platform = spec.architecture.platform
+        if spec.architecture.platform_os is not None and isinstance(
+            spec.architecture.platform_os,spack.architecture.OperatingSystem):
+            return False
 
-    def concretize_architecture(self, spec):
-        """If the spec already had an architecture, return.  Otherwise if
-           the root of the DAG has an architecture, then use that.
-           Otherwise take the system's default architecture.
-
-           Intuition: Architectures won't be set a lot, and generally you
-           want the host system's architecture.  When architectures are
-           mised in a spec, it is likely because the tool requries a
-           cross-compiled component, e.g. for tools that run on BlueGene
-           or Cray machines.  These constraints will likely come directly
-           from packages, so require the user to be explicit if they want
-           to mess with the architecture, and revert to the default when
-           they're not explicit.
-        """
-        if spec.architecture is not None:
+        if spec.root.architecture and spec.root.architecture.platform_os:
+            if isinstance(spec.root.architecture.platform_os,spack.architecture.OperatingSystem):
+                spec.architecture.platform_os = spec.root.architecture.platform_os
+        else:
+            spec.architecture.platform_os = spec.architecture.platform.operating_system('default_os')
+        return True #changed
+
+    def _concretize_target(self, spec):
+        platform = spec.architecture.platform
+        if spec.architecture.target is not None and isinstance(
+                spec.architecture.target, spack.architecture.Target):
             return False
+        if spec.root.architecture and spec.root.architecture.target:
+            if isinstance(spec.root.architecture.target,spack.architecture.Target):
+                spec.architecture.target = spec.root.architecture.target
+        else:
+            spec.architecture.target = spec.architecture.platform.target('default_target')
+        return True #changed
 
-        if spec.root.architecture:
-            spec.architecture = spec.root.architecture
+    def _concretize_platform(self, spec):
+        if spec.architecture.platform is not None and isinstance(
+                spec.architecture.platform, spack.architecture.Platform):
+            return False
+        if spec.root.architecture and spec.root.architecture.platform:
+            if isinstance(spec.root.architecture.platform,spack.architecture.Platform):
+                spec.architecture.platform = spec.root.architecture.platform
         else:
-            spec.architecture = spack.architecture.sys_type()
+            spec.architecture.platform = spack.architecture.sys_type()
+        return True #changed?
+
+    def concretize_architecture(self, spec):
+        """If the spec is empty provide the defaults of the platform. If the
+        architecture is not a basestring, then check if either the platform,
+        target or operating system are concretized. If any of the fields are
+        changed then return True. If everything is concretized (i.e the
+        architecture attribute is a namedtuple of classes) then return False.
+        If the target is a string type, then convert the string into a
+        concretized architecture. If it has no architecture and the root of the
+        DAG has an architecture, then use the root otherwise use the defaults
+        on the platform.
+        """
+        if spec.architecture is None:
+            # Set the architecture to all defaults
+            spec.architecture = spack.architecture.Arch()
+            return True
+
+            # Concretize the operating_system and target based of the spec
+        ret =  any((self._concretize_platform(spec),
+                    self._concretize_operating_system(spec),
+                    self._concretize_target(spec)))
+        return ret
 
-        assert(spec.architecture is not None)
-        return True   # changed
 
 
     def concretize_variants(self, spec):
@@ -238,6 +272,23 @@ class DefaultConcretizer(object):
            build with the compiler that will be used by libraries that
            link to this one, to maximize compatibility.
         """
+        # Pass on concretizing the compiler if the target is not yet determined
+        if not spec.architecture.platform_os:
+            #Although this usually means changed, this means awaiting other changes
+            return True
+
+        # Only use a matching compiler if it is of the proper style
+        # Takes advantage of the proper logic already existing in compiler_for_spec
+        # Should think whether this can be more efficient
+        def _proper_compiler_style(cspec, arch):
+            platform = arch.platform
+            compilers = spack.compilers.compilers_for_spec(cspec,
+                                                           platform=platform)
+            return filter(lambda c: c.operating_system ==
+                                    arch.platform_os, compilers)
+            #return compilers
+
+
         all_compilers = spack.compilers.all_compilers()
 
         if (spec.compiler and
@@ -247,6 +298,7 @@ class DefaultConcretizer(object):
 
         #Find the another spec that has a compiler, or the root if none do
         other_spec = spec if spec.compiler else find_spec(spec, lambda(x) : x.compiler)
+
         if not other_spec:
             other_spec = spec.root
         other_compiler = other_spec.compiler
@@ -265,7 +317,12 @@ class DefaultConcretizer(object):
             raise UnavailableCompilerVersionError(other_compiler)
 
         # copy concrete version into other_compiler
-        spec.compiler = matches[0].copy()
+        index = 0
+        while not _proper_compiler_style(matches[index], spec.architecture):
+            index += 1
+            if index == len(matches) - 1:
+                raise NoValidVersionError(spec)
+        spec.compiler = matches[index].copy()
         assert(spec.compiler.concrete)
         return True  # things changed.
 
@@ -276,15 +333,21 @@ class DefaultConcretizer(object):
         compiler is used, defaulting to no compiler flags in the spec.
         Default specs set at the compiler level will still be added later.
         """
+
+            
+        if not spec.architecture.platform_os:
+            #Although this usually means changed, this means awaiting other changes
+            return True
+
         ret = False
         for flag in spack.spec.FlagMap.valid_compiler_flags():
             try:
                 nearest = next(p for p in spec.traverse(direction='parents')
                                if ((p.compiler == spec.compiler and p is not spec)
                                and flag in p.compiler_flags))
-                if ((not flag in spec.compiler_flags) or
-                    sorted(spec.compiler_flags[flag]) != sorted(nearest.compiler_flags[flag])):
-                    if flag in spec.compiler_flags:
+                if not flag in spec.compiler_flags or \
+                    not (sorted(spec.compiler_flags[flag]) >= sorted(nearest.compiler_flags[flag])):
+                    if flag in spec.compiler_flags: 
                         spec.compiler_flags[flag] = list(set(spec.compiler_flags[flag]) |
                                                          set(nearest.compiler_flags[flag]))
                     else:
@@ -307,7 +370,7 @@ class DefaultConcretizer(object):
         # Include the compiler flag defaults from the config files
         # This ensures that spack will detect conflicts that stem from a change
         # in default compiler flags.
-        compiler = spack.compilers.compiler_for_spec(spec.compiler)
+        compiler = spack.compilers.compiler_for_spec(spec.compiler, spec.architecture)
         for flag in compiler.flags:
             if flag not in spec.compiler_flags:
                 spec.compiler_flags[flag] = compiler.flags[flag]
diff --git a/lib/spack/spack/config.py b/lib/spack/spack/config.py
index ec37bd290c..db0787edc6 100644
--- a/lib/spack/spack/config.py
+++ b/lib/spack/spack/config.py
@@ -135,7 +135,7 @@ from yaml.error import MarkedYAMLError
 
 # Hacked yaml for configuration files preserves line numbers.
 import spack.util.spack_yaml as syaml
-
+from spack.build_environment import get_path_from_module
 
 """Dict from section names -> schema for that section."""
 section_schemas = {
@@ -146,18 +146,17 @@ section_schemas = {
         'additionalProperties': False,
         'patternProperties': {
             'compilers:?': {  # optional colon for overriding site config.
-                'type': 'object',
-                'default': {},
-                'additionalProperties': False,
-                'patternProperties': {
-                    r'\w[\w-]*': {           # architecture
+                'type': 'array',
+                'items': {
+                    'compiler': {
                         'type': 'object',
                         'additionalProperties': False,
-                        'patternProperties': {
-                            r'\w[\w-]*@\w[\w-]*': {   # compiler spec
+                        'required': ['paths', 'spec', 'modules', 'operating_system'],
+                        'properties': {
+                            'paths': {
                                 'type': 'object',
-                                'additionalProperties': False,
                                 'required': ['cc', 'cxx', 'f77', 'fc'],
+                                'additionalProperties': False,
                                 'properties': {
                                     'cc':  { 'anyOf': [ {'type' : 'string' },
                                                         {'type' : 'null' }]},
@@ -167,8 +166,27 @@ section_schemas = {
                                                         {'type' : 'null' }]},
                                     'fc':  { 'anyOf': [ {'type' : 'string' },
                                                         {'type' : 'null' }]},
-                                },},},},},},},},
-
+                                    'cflags': { 'anyOf': [ {'type' : 'string' },
+                                                        {'type' : 'null' }]},
+                                    'cxxflags': { 'anyOf': [ {'type' : 'string' },
+                                                        {'type' : 'null' }]},
+                                    'fflags': { 'anyOf': [ {'type' : 'string' },
+                                                        {'type' : 'null' }]},
+                                    'cppflags': { 'anyOf': [ {'type' : 'string' },
+                                                        {'type' : 'null' }]},
+                                    'ldflags': { 'anyOf': [ {'type' : 'string' },
+                                                        {'type' : 'null' }]},
+                                    'ldlibs': { 'anyOf': [ {'type' : 'string' },
+                                                        {'type' : 'null' }]}}},
+                            'spec': { 'type': 'string'},
+                            'operating_system': { 'type': 'string'},
+                            'alias': { 'anyOf': [ {'type' : 'string'},
+                                                    {'type' : 'null' }]},
+                            'modules': { 'anyOf': [ {'type' : 'string'},
+                                                    {'type' : 'null' },
+                                                    {'type': 'array'},
+                                                    ]}
+                            },},},},},},
     'mirrors': {
         '$schema': 'http://json-schema.org/schema#',
         'title': 'Spack mirror configuration file schema',
@@ -194,7 +212,6 @@ section_schemas = {
                 'default': [],
                 'items': {
                     'type': 'string'},},},},
-
     'packages': {
         '$schema': 'http://json-schema.org/schema#',
         'title': 'Spack package configuration file schema',
@@ -224,6 +241,10 @@ section_schemas = {
                                 'type':  'boolean',
                                 'default': True,
                              },
+                            'modules': {
+                                'type' : 'object',
+                                'default' : {},
+                             },
                             'providers': {
                                 'type':  'object',
                                 'default': {},
@@ -563,8 +584,7 @@ def _merge_yaml(dest, source):
 
     # Source list is prepended (for precedence)
     if they_are(list):
-        seen = set(source)
-        dest[:] = source + [x for x in dest if x not in seen]
+        dest[:] = source + [x for x in dest if x not in source]
         return dest
 
     # Source dict is merged into dest.
@@ -667,7 +687,8 @@ def spec_externals(spec):
 
     external_specs = []
     pkg_paths = allpkgs.get(name, {}).get('paths', None)
-    if not pkg_paths:
+    pkg_modules = allpkgs.get(name, {}).get('modules', None)
+    if (not pkg_paths) and (not pkg_modules):
         return []
 
     for external_spec, path in pkg_paths.iteritems():
@@ -678,6 +699,17 @@ def spec_externals(spec):
         external_spec = spack.spec.Spec(external_spec, external=path)
         if external_spec.satisfies(spec):
             external_specs.append(external_spec)
+
+    for external_spec, module in pkg_modules.iteritems():
+        if not module:
+            continue
+
+        path = get_path_from_module(module)
+
+        external_spec = spack.spec.Spec(external_spec, external=path, external_module=module)
+        if external_spec.satisfies(spec):
+            external_specs.append(external_spec)
+
     return external_specs
 
 
diff --git a/lib/spack/spack/database.py b/lib/spack/spack/database.py
index e768ddf5fe..f941346bb1 100644
--- a/lib/spack/spack/database.py
+++ b/lib/spack/spack/database.py
@@ -214,9 +214,10 @@ class Database(object):
 
         # Add dependencies from other records in the install DB to
         # form a full spec.
-        for dep_hash in spec_dict[spec.name]['dependencies'].values():
-            child = self._read_spec_from_yaml(dep_hash, installs, hash_key)
-            spec._add_dependency(child)
+        if 'dependencies' in spec_dict[spec.name]:
+            for dep_hash in spec_dict[spec.name]['dependencies'].values():
+                child = self._read_spec_from_yaml(dep_hash, installs, hash_key)
+                spec._add_dependency(child)
 
         # Specs from the database need to be marked concrete because
         # they represent actual installations.
@@ -289,7 +290,8 @@ class Database(object):
             except Exception as e:
                 tty.warn("Invalid database reecord:",
                          "file:  %s" % self._index_path,
-                         "hash:  %s" % hash_key, "cause: %s" % str(e))
+                         "hash:  %s" % hash_key,
+                         "cause: %s: %s" % (type(e).__name__, str(e)))
                 raise
 
         self._data = data
@@ -309,7 +311,11 @@ class Database(object):
                 for spec in directory_layout.all_specs():
                     # Create a spec for each known package and add it.
                     path = directory_layout.path_for_spec(spec)
-                    self._add(spec, path, directory_layout)
+                    old_info = old_data.get(spec.dag_hash())
+                    explicit = False
+                    if old_info is not None:
+                        explicit = old_info.explicit
+                    self._add(spec, path, directory_layout, explicit=explicit)
 
                 self._check_ref_counts()
 
diff --git a/lib/spack/spack/directives.py b/lib/spack/spack/directives.py
index 51b26773e2..ca8f21dc08 100644
--- a/lib/spack/spack/directives.py
+++ b/lib/spack/spack/directives.py
@@ -257,7 +257,7 @@ def variant(pkg, name, default=False, description=""):
     """Define a variant for the package. Packager can specify a default
     value (on or off) as well as a text description."""
 
-    default = bool(default)
+    default     = default
     description = str(description).strip()
 
     if not re.match(spack.spec.identifier_re, name):
diff --git a/lib/spack/spack/directory_layout.py b/lib/spack/spack/directory_layout.py
index 32d27d7bd0..7e20365b0f 100644
--- a/lib/spack/spack/directory_layout.py
+++ b/lib/spack/spack/directory_layout.py
@@ -165,7 +165,7 @@ class DirectoryLayout(object):
 class YamlDirectoryLayout(DirectoryLayout):
     """Lays out installation directories like this::
            <install root>/
-               <architecture>/
+               <target>/
                    <compiler>-<compiler version>/
                        <name>-<version>-<variants>-<hash>
 
@@ -207,8 +207,7 @@ class YamlDirectoryLayout(DirectoryLayout):
             spec.version,
             spec.dag_hash(self.hash_len))
 
-        path = join_path(
-            spec.architecture,
+        path = join_path(spec.architecture,
             "%s-%s" % (spec.compiler.name, spec.compiler.version),
             dir_name)
 
diff --git a/lib/spack/spack/fetch_strategy.py b/lib/spack/spack/fetch_strategy.py
index 2607d0a7f4..6f28ec34b2 100644
--- a/lib/spack/spack/fetch_strategy.py
+++ b/lib/spack/spack/fetch_strategy.py
@@ -1,4 +1,4 @@
-##############################################################################
+#
 # Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.
 # Produced at the Lawrence Livermore National Laboratory.
 #
@@ -21,7 +21,7 @@
 # You should have received a copy of the GNU Lesser General Public
 # License along with this program; if not, write to the Free Software
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-##############################################################################
+#
 """
 Fetch strategies are used to download source code into a staging area
 in order to build it.  They need to define the following methods:
@@ -75,11 +75,13 @@ def _needs_stage(fun):
 
 
 class FetchStrategy(object):
+
     """Superclass of all fetch strategies."""
     enabled = False  # Non-abstract subclasses should be enabled.
     required_attributes = None  # Attributes required in version() args.
 
     class __metaclass__(type):
+
         """This metaclass registers all fetch strategies in a list."""
 
         def __init__(cls, name, bases, dict):
@@ -126,6 +128,7 @@ class FetchStrategy(object):
 
 @pattern.composite(interface=FetchStrategy)
 class FetchStrategyComposite(object):
+
     """
     Composite for a FetchStrategy object. Implements the GoF composite pattern.
     """
@@ -134,6 +137,7 @@ class FetchStrategyComposite(object):
 
 
 class URLFetchStrategy(FetchStrategy):
+
     """FetchStrategy that pulls source code from a URL for an archive,
        checks the archive against a checksum,and decompresses the archive.
     """
@@ -235,12 +239,13 @@ class URLFetchStrategy(FetchStrategy):
         # redirects properly.
         content_types = re.findall(r'Content-Type:[^\r\n]+', headers)
         if content_types and 'text/html' in content_types[-1]:
-            tty.warn(
-                "The contents of " + self.archive_file + " look like HTML.",
-                "The checksum will likely be bad.  If it is, you can use",
-                "'spack clean <package>' to remove the bad archive, then fix",
-                "your internet gateway issue and install again.")
-
+            tty.warn("The contents of ",
+                     (self.archive_file if self.archive_file is not None
+                      else "the archive"),
+                     " look like HTML.",
+                     "The checksum will likely be bad.  If it is, you can use",
+                     "'spack clean <package>' to remove the bad archive, then",
+                     "fix your internet gateway issue and install again.")
         if save_file:
             os.rename(partial_file, save_file)
 
@@ -371,6 +376,7 @@ class CacheURLFetchStrategy(URLFetchStrategy):
 
 
 class VCSFetchStrategy(FetchStrategy):
+
     def __init__(self, name, *rev_types, **kwargs):
         super(VCSFetchStrategy, self).__init__()
         self.name = name
@@ -425,6 +431,7 @@ class VCSFetchStrategy(FetchStrategy):
 
 
 class GoFetchStrategy(VCSFetchStrategy):
+
     """
     Fetch strategy that employs the `go get` infrastructure
     Use like this in a package:
@@ -484,6 +491,7 @@ class GoFetchStrategy(VCSFetchStrategy):
 
 
 class GitFetchStrategy(VCSFetchStrategy):
+
     """
     Fetch strategy that gets source code from a git repository.
     Use like this in a package:
@@ -604,6 +612,7 @@ class GitFetchStrategy(VCSFetchStrategy):
 
 
 class SvnFetchStrategy(VCSFetchStrategy):
+
     """Fetch strategy that gets source code from a subversion repository.
        Use like this in a package:
 
@@ -680,6 +689,7 @@ class SvnFetchStrategy(VCSFetchStrategy):
 
 
 class HgFetchStrategy(VCSFetchStrategy):
+
     """
     Fetch strategy that gets source code from a Mercurial repository.
     Use like this in a package:
@@ -850,11 +860,13 @@ class FsCache(object):
 
 
 class FetchError(spack.error.SpackError):
+
     def __init__(self, msg, long_msg=None):
         super(FetchError, self).__init__(msg, long_msg)
 
 
 class FailedDownloadError(FetchError):
+
     """Raised wen a download fails."""
 
     def __init__(self, url, msg=""):
@@ -864,16 +876,19 @@ class FailedDownloadError(FetchError):
 
 
 class NoArchiveFileError(FetchError):
+
     def __init__(self, msg, long_msg):
         super(NoArchiveFileError, self).__init__(msg, long_msg)
 
 
 class NoDigestError(FetchError):
+
     def __init__(self, msg, long_msg=None):
         super(NoDigestError, self).__init__(msg, long_msg)
 
 
 class InvalidArgsError(FetchError):
+
     def __init__(self, pkg, version):
         msg = ("Could not construct a fetch strategy for package %s at "
                "version %s")
@@ -882,6 +897,7 @@ class InvalidArgsError(FetchError):
 
 
 class ChecksumError(FetchError):
+
     """Raised when archive fails to checksum."""
 
     def __init__(self, message, long_msg=None):
@@ -889,6 +905,7 @@ class ChecksumError(FetchError):
 
 
 class NoStageError(FetchError):
+
     """Raised when fetch operations are called before set_stage()."""
 
     def __init__(self, method):
diff --git a/lib/spack/spack/hooks/licensing.py b/lib/spack/spack/hooks/licensing.py
index 0f63b0e05a..9010b84154 100644
--- a/lib/spack/spack/hooks/licensing.py
+++ b/lib/spack/spack/hooks/licensing.py
@@ -26,7 +26,7 @@ import os
 
 import spack
 import llnl.util.tty as tty
-from llnl.util.filesystem import join_path
+from llnl.util.filesystem import join_path, mkdirp
 
 
 def pre_install(pkg):
@@ -154,6 +154,9 @@ def symlink_license(pkg):
     target = pkg.global_license_file
     for filename in pkg.license_files:
         link_name = join_path(pkg.prefix, filename)
+        license_dir = os.path.dirname(link_name)
+        if not os.path.exists(license_dir):
+            mkdirp(license_dir)
         if os.path.exists(target):
             os.symlink(target, link_name)
             tty.msg("Added local symlink %s to global license file" %
diff --git a/lib/spack/spack/operating_systems/__init__.py b/lib/spack/spack/operating_systems/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/spack/spack/operating_systems/__init__.py
diff --git a/lib/spack/spack/operating_systems/cnl.py b/lib/spack/spack/operating_systems/cnl.py
new file mode 100644
index 0000000000..c160a60be8
--- /dev/null
+++ b/lib/spack/spack/operating_systems/cnl.py
@@ -0,0 +1,62 @@
+import re
+import os
+
+from spack.architecture import OperatingSystem
+from spack.util.executable import *
+import spack.spec
+from spack.util.multiproc import parmap
+import spack.compilers
+
+class Cnl(OperatingSystem):
+    """ Compute Node Linux (CNL) is the operating system used for the Cray XC
+    series super computers. It is a very stripped down version of GNU/Linux.
+    Any compilers found through this operating system will be used with
+    modules. If updated, user must make sure that version and name are 
+    updated to indicate that OS has been upgraded (or downgraded)
+    """
+    def __init__(self):
+        name = 'CNL'
+        version = '10'
+        super(Cnl, self).__init__(name, version)
+
+
+    def find_compilers(self, *paths):
+        types = spack.compilers.all_compiler_types()
+        compiler_lists = parmap(lambda cmp_cls: self.find_compiler(cmp_cls, *paths), types)
+
+        # ensure all the version calls we made are cached in the parent
+        # process, as well.  This speeds up Spack a lot.
+        clist = reduce(lambda x,y: x+y, compiler_lists)
+        return clist
+
+
+    def find_compiler(self, cmp_cls, *paths):
+        compilers = []
+        if cmp_cls.PrgEnv:
+            if not cmp_cls.PrgEnv_compiler:
+                tty.die('Must supply PrgEnv_compiler with PrgEnv')
+
+            modulecmd = which('modulecmd')
+            modulecmd.add_default_arg('python')
+
+            # Save the environment variable to restore later
+            old_modulepath = os.environ['MODULEPATH']
+            # if given any explicit paths, search them for module files too
+            if paths:
+                module_paths = ':' + ':'.join(p for p in paths)
+                os.environ['MODULEPATH'] = module_paths
+        
+            output = modulecmd('avail', cmp_cls.PrgEnv_compiler, output=str, error=str)
+            matches = re.findall(r'(%s)/([\d\.]+[\d])' % cmp_cls.PrgEnv_compiler, output)
+            for name, version in matches:
+                v = version
+                comp = cmp_cls(spack.spec.CompilerSpec(name + '@' + v), self,
+                           ['cc', 'CC', 'ftn'], [cmp_cls.PrgEnv, name +'/' + v])
+
+                compilers.append(comp)
+
+            # Restore modulepath environment variable
+            if paths:
+                os.environ['MODULEPATH'] = old_modulepath
+
+        return compilers
diff --git a/lib/spack/spack/operating_systems/linux_distro.py b/lib/spack/spack/operating_systems/linux_distro.py
new file mode 100644
index 0000000000..2e3c72719b
--- /dev/null
+++ b/lib/spack/spack/operating_systems/linux_distro.py
@@ -0,0 +1,22 @@
+import re
+import platform as py_platform
+from spack.architecture import OperatingSystem
+
+class LinuxDistro(OperatingSystem):
+    """ This class will represent the autodetected operating system
+        for a Linux System. Since there are many different flavors of
+        Linux, this class will attempt to encompass them all through
+        autodetection using the python module platform and the method
+        platform.dist()
+    """
+    def __init__(self):
+        distname, version, _ = py_platform.linux_distribution(
+            full_distribution_name=False)
+
+        # Grabs major version from tuple on redhat; on other platforms
+        # grab the first legal identifier in the version field.  On
+        # debian you get things like 'wheezy/sid'; sid means unstable.
+        # We just record 'wheezy' and don't get quite so detailed.
+        version = re.split(r'[^\w-]', version)[0]
+
+        super(LinuxDistro, self).__init__(distname, version)
diff --git a/lib/spack/spack/operating_systems/mac_os.py b/lib/spack/spack/operating_systems/mac_os.py
new file mode 100644
index 0000000000..f35b3ca577
--- /dev/null
+++ b/lib/spack/spack/operating_systems/mac_os.py
@@ -0,0 +1,29 @@
+import platform as py_platform
+from spack.architecture import OperatingSystem
+
+class MacOs(OperatingSystem):
+    """This class represents the macOS operating system. This will be
+    auto detected using the python platform.mac_ver. The macOS
+    platform will be represented using the major version operating
+    system name, i.e el capitan, yosemite...etc.
+    """
+
+    def __init__(self):
+        """ Autodetects the mac version from a dictionary. Goes back as
+            far as 10.6 snowleopard. If the user has an older mac then
+            the version will just be a generic mac_os.
+        """
+        mac_releases = {'10.6': "snowleopard",
+                        "10.7": "lion",
+                        "10.8": "mountainlion",
+                        "10.9": "mavericks",
+                        "10.10": "yosemite",
+                        "10.11": "elcapitan",
+                        "10.12": "sierra"}
+
+        mac_ver = py_platform.mac_ver()[0][:-2]
+        name = mac_releases.get(mac_ver, "macos")
+        super(MacOs, self).__init__(name, mac_ver)
+
+    def __str__(self):
+        return self.name
diff --git a/lib/spack/spack/package.py b/lib/spack/spack/package.py
index cbf50e56f6..c5250d17c0 100644
--- a/lib/spack/spack/package.py
+++ b/lib/spack/spack/package.py
@@ -398,13 +398,19 @@ class Package(object):
             spack.repo.get(self.extendee_spec)._check_extendable()
 
     @property
+    def global_license_dir(self):
+        """Returns the directory where global license files for all
+           packages are stored."""
+        spack_root = ancestor(__file__, 4)
+        return join_path(spack_root, 'etc', 'spack', 'licenses')
+
+    @property
     def global_license_file(self):
-        """Returns the path where a global license file should be stored."""
+        """Returns the path where a global license file for this
+           particular package should be stored."""
         if not self.license_files:
             return
-        spack_root = ancestor(__file__, 4)
-        global_license_dir = join_path(spack_root, 'etc', 'spack', 'licenses')
-        return join_path(global_license_dir, self.name,
+        return join_path(self.global_license_dir, self.name,
                          os.path.basename(self.license_files[0]))
 
     @property
@@ -676,11 +682,13 @@ class Package(object):
         return self.spec.prefix
 
     @property
+    #TODO: Change this to architecture
     def compiler(self):
         """Get the spack.compiler.Compiler object used to build this package"""
         if not self.spec.concrete:
             raise ValueError("Can only get a compiler for a concrete package.")
-        return spack.compilers.compiler_for_spec(self.spec.compiler)
+        return spack.compilers.compiler_for_spec(self.spec.compiler, 
+                self.spec.architecture)
 
     def url_version(self, version):
         """
diff --git a/lib/spack/spack/platforms/__init__.py b/lib/spack/spack/platforms/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/spack/spack/platforms/__init__.py
diff --git a/lib/spack/spack/platforms/bgq.py b/lib/spack/spack/platforms/bgq.py
new file mode 100644
index 0000000000..e0eb76f336
--- /dev/null
+++ b/lib/spack/spack/platforms/bgq.py
@@ -0,0 +1,18 @@
+import os
+from spack.architecture import Platform, Target
+
+class Bgq(Platform):
+    priority    = 30
+    front_end   = 'power7'
+    back_end    = 'powerpc'
+    default     = 'powerpc'
+
+    def __init__(self):
+        super(Bgq, self).__init__('bgq')
+        self.add_target(self.front_end, Target(self.front_end))
+        self.add_target(self.back_end, Target(self.back_end,))
+
+    @classmethod
+    def detect(self):
+        return os.path.exists('/bgsys')
+    
diff --git a/lib/spack/spack/platforms/cray_xc.py b/lib/spack/spack/platforms/cray_xc.py
new file mode 100644
index 0000000000..e710303e23
--- /dev/null
+++ b/lib/spack/spack/platforms/cray_xc.py
@@ -0,0 +1,46 @@
+import os
+from spack.architecture import Platform, Target
+from spack.operating_systems.linux_distro import LinuxDistro
+from spack.operating_systems.cnl import Cnl
+
+class CrayXc(Platform):
+    priority    = 20
+    front_end   = 'sandybridge'
+    back_end    = 'ivybridge'
+    default     = 'ivybridge'
+
+    front_os    = "SuSE11"
+    back_os     = "CNL10"
+    default_os  = "CNL10" 
+
+    def __init__(self):
+        ''' Since cori doesn't have ivybridge as a front end it's better
+            if we use CRAY_CPU_TARGET as the default. This will ensure
+            that if we're on a XC-40 or XC-30 then we can detect the target
+        '''
+        super(CrayXc, self).__init__('cray_xc')
+
+        # Handle the default here so we can check for a key error
+        if 'CRAY_CPU_TARGET' in os.environ:
+            self.default = os.environ['CRAY_CPU_TARGET']
+
+        # Change the defaults to haswell if we're on an XC40
+        if self.default == 'haswell':
+            self.front_end = self.default
+            self.back_end = self.default
+
+        # Could switch to use modules and fe targets for front end
+        # Currently using compilers by path for front end.
+        self.add_target('sandybridge', Target('sandybridge'))
+        self.add_target('ivybridge', 
+                        Target('ivybridge', 'craype-ivybridge'))
+        self.add_target('haswell', 
+                        Target('haswell','craype-haswell'))         
+
+        self.add_operating_system('SuSE11', LinuxDistro())
+        self.add_operating_system('CNL10', Cnl())
+
+    @classmethod
+    def detect(self):
+        return os.path.exists('/opt/cray/craype')
+
diff --git a/lib/spack/spack/platforms/darwin.py b/lib/spack/spack/platforms/darwin.py
new file mode 100644
index 0000000000..d47dd640f9
--- /dev/null
+++ b/lib/spack/spack/platforms/darwin.py
@@ -0,0 +1,26 @@
+import subprocess
+from spack.architecture import Platform, Target
+from spack.operating_systems.mac_os import MacOs
+
+class Darwin(Platform):
+    priority    = 89
+    front_end   = 'x86_64'
+    back_end    = 'x86_64'
+    default     = 'x86_64'
+
+    def __init__(self):
+        super(Darwin, self).__init__('darwin')
+        self.add_target(self.default, Target(self.default))
+        mac_os = MacOs()
+
+        self.default_os = str(mac_os)
+        self.front_os   = str(mac_os)
+        self.back_os    = str(mac_os)
+
+        self.add_operating_system(str(mac_os), mac_os)
+
+    @classmethod
+    def detect(self):
+        platform = subprocess.Popen(['uname', '-a'], stdout = subprocess.PIPE)
+        platform, _ = platform.communicate()
+        return 'darwin' in platform.strip().lower()
diff --git a/lib/spack/spack/platforms/linux.py b/lib/spack/spack/platforms/linux.py
new file mode 100644
index 0000000000..4d8adac384
--- /dev/null
+++ b/lib/spack/spack/platforms/linux.py
@@ -0,0 +1,24 @@
+import subprocess
+from spack.architecture import Platform, Target
+from spack.operating_systems.linux_distro import LinuxDistro
+
+class Linux(Platform):
+    priority    = 90
+    front_end   = 'x86_64'
+    back_end    = 'x86_64'
+    default     = 'x86_64'
+
+    def __init__(self):
+        super(Linux, self).__init__('linux')
+        self.add_target(self.default, Target(self.default))
+        linux_dist = LinuxDistro()
+        self.default_os = str(linux_dist)
+        self.front_os = self.default_os
+        self.back_os = self.default_os
+        self.add_operating_system(str(linux_dist), linux_dist)
+
+    @classmethod
+    def detect(self):
+        platform = subprocess.Popen(['uname', '-a'], stdout = subprocess.PIPE)
+        platform, _ = platform.communicate()
+        return 'linux' in platform.strip().lower()
diff --git a/lib/spack/spack/platforms/test.py b/lib/spack/spack/platforms/test.py
new file mode 100644
index 0000000000..8fa2585a7a
--- /dev/null
+++ b/lib/spack/spack/platforms/test.py
@@ -0,0 +1,28 @@
+import subprocess
+from spack.architecture import Platform, Target
+from spack.operating_systems.linux_distro import LinuxDistro
+from spack.operating_systems.cnl import Cnl
+
+
+class Test(Platform):
+    priority    = 1000000
+    front_end   = 'x86_32'
+    back_end    = 'x86_64'
+    default     = 'x86_64'
+    
+    back_os = 'CNL10'
+    default_os = 'CNL10'
+
+    def __init__(self):
+        super(Test, self).__init__('test')
+        self.add_target(self.default, Target(self.default))
+        self.add_target(self.front_end, Target(self.front_end))
+
+        self.add_operating_system(self.default_os, Cnl())
+        linux_dist = LinuxDistro()
+        self.front_os = linux_dist.name
+        self.add_operating_system(self.front_os, linux_dist)
+
+    @classmethod
+    def detect(self):
+        return True
diff --git a/lib/spack/spack/spec.py b/lib/spack/spack/spec.py
index 7c09af4c21..54219ec1b4 100644
--- a/lib/spack/spack/spec.py
+++ b/lib/spack/spack/spec.py
@@ -1,4 +1,4 @@
-#
+##############################################################################
 # Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.
 # Produced at the Lawrence Livermore National Laboratory.
 #
@@ -18,10 +18,10 @@
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
 # conditions of the GNU Lesser General Public License for more details.
 #
-# You should have received a copy of the GNU Lesser General Public
-# License along with this program; if not, write to the Free Software
-# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
 """
 Spack allows very fine-grained control over how packages are installed and
 over how they are built and configured.  To make this easy, it has its own
@@ -96,8 +96,10 @@ specs to avoid ambiguity.  Both are provided because ~ can cause shell
 expansion when it is the first character in an id typed on the command line.
 """
 import sys
+import itertools
 import hashlib
 import base64
+import imp
 from StringIO import StringIO
 from operator import attrgetter
 import yaml
@@ -106,16 +108,22 @@ from yaml.error import MarkedYAMLError
 import llnl.util.tty as tty
 from llnl.util.lang import *
 from llnl.util.tty.color import *
+from llnl.util.filesystem import join_path
 
 import spack
+import spack.architecture
 import spack.parse
 import spack.error
 import spack.compilers as compilers
 
+# TODO: move display_specs to some other location.
+from spack.cmd.find import display_specs
 from spack.version import *
 from spack.util.string import *
 from spack.util.prefix import Prefix
+from spack.util.naming import mod_to_class
 from spack.virtual import ProviderIndex
+from spack.build_environment import get_path_from_module, load_module
 
 # Valid pattern for an identifier in Spack
 identifier_re = r'\w[\w-]*'
@@ -165,7 +173,6 @@ def colorize_spec(spec):
     """Returns a spec colorized according to the colors specified in
        color_formats."""
     class insert_color:
-
         def __init__(self):
             self.last = None
 
@@ -183,11 +190,9 @@ def colorize_spec(spec):
 
 @key_ordering
 class CompilerSpec(object):
-
     """The CompilerSpec field represents the compiler or range of compiler
        versions that a package should be built with.  CompilerSpecs have a
        name and a version list. """
-
     def __init__(self, *args):
         nargs = len(args)
         if nargs == 1:
@@ -293,7 +298,6 @@ class VariantSpec(object):
        on the particular package being built, and each named variant can
        be enabled or disabled.
     """
-
     def __init__(self, name, value):
         self.name = name
         self.value = value
@@ -488,7 +492,8 @@ class Spec(object):
         self._concrete = kwargs.get('concrete', False)
 
         # Allow a spec to be constructed with an external path.
-        self.external = kwargs.get('external', None)
+        self.external  = kwargs.get('external', None)
+        self.external_module = kwargs.get('external_module', None)
 
         # This allows users to construct a spec DAG with literals.
         # Note that given two specs a and b, Spec(a) copies a, but
@@ -520,8 +525,33 @@ class Spec(object):
         Known flags currently include "arch"
         """
         valid_flags = FlagMap.valid_compiler_flags()
-        if name == 'arch':
-            self._set_architecture(value)
+        if name == 'arch' or name == 'architecture':
+            parts = value.split('-')
+            if len(parts) == 3:
+                platform, op_sys, target = parts
+            else:
+                platform, op_sys, target = None, None, value
+
+            assert(self.architecture.platform is None)
+            assert(self.architecture.platform_os is None)
+            assert(self.architecture.target is None)
+            assert(self.architecture.os_string is None)
+            assert(self.architecture.target_string is None)
+            self._set_platform(platform)
+            self._set_os(op_sys)
+            self._set_target(target)
+        elif name == 'platform':
+            self._set_platform(value)
+        elif name == 'os' or name == 'operating_system':
+            if self.architecture.platform:
+                self._set_os(value)
+            else:
+                self.architecture.os_string = value
+        elif name == 'target':
+            if self.architecture.platform:
+                self._set_target(value)
+            else:
+                self.architecture.target_string = value
         elif name in valid_flags:
             assert(self.compiler_flags is not None)
             self.compiler_flags[name] = value.split()
@@ -535,12 +565,49 @@ class Spec(object):
                 "Spec for '%s' cannot have two compilers." % self.name)
         self.compiler = compiler
 
-    def _set_architecture(self, architecture):
-        """Called by the parser to set the architecture."""
-        if self.architecture:
-            raise DuplicateArchitectureError(
-                "Spec for '%s' cannot have two architectures." % self.name)
-        self.architecture = architecture
+    def _set_platform(self, value):
+        """Called by the parser to set the architecture platform"""
+        if isinstance(value, basestring):
+            mod_path = spack.platform_path
+            mod_string = 'spack.platformss'
+            names = list_modules(mod_path)
+            if value in names:
+                # Create a platform object from the name
+                mod_name = mod_string + value
+                path = join_path(mod_path, value) + '.py'
+                mod = imp.load_source(mod_name, path)
+                class_name = mod_to_class(value)
+                if not hasattr(mod, class_name):
+                    tty.die('No class %s defined in %s' % (class_name, mod_name))
+                cls = getattr(mod, class_name)
+                if not inspect.isclass(cls):
+                    tty.die('%s.%s is not a class' % (mod_name, class_name))
+                platform = cls()
+            else:
+                tty.die("No platform class %s defined." % value)
+        else:
+            # The value is a platform
+            platform = value
+
+        self.architecture.platform = platform
+
+        # Set os and target if we previously got strings for them
+        if self.architecture.os_string:
+            self._set_os(self.architecture.os_string)
+            self.architecture.os_string = None
+        if self.architecture.target_string:
+            self._set_target(self.architecture.target_string)
+            self.architecture.target_string = None
+
+    def _set_os(self, value):
+        """Called by the parser to set the architecture operating system"""
+        if self.architecture.platform:
+            self.architecture.platform_os = self.architecture.platform.operating_system(value)
+
+    def _set_target(self, value):
+        """Called by the parser to set the architecture target"""
+        if self.architecture.platform:
+            self.architecture.target = self.architecture.platform.target(value)
 
     def _add_dependency(self, spec):
         """Called by the parser to add another spec as a dependency."""
@@ -612,15 +679,15 @@ class Spec(object):
         if self._concrete:
             return True
 
-        self._concrete = bool(not self.virtual and
-                              self.namespace is not None and
-                              self.versions.concrete and
-                              self.variants.concrete and
-                              self.architecture and
-                              self.compiler and
-                              self.compiler.concrete and
-                              self.compiler_flags.concrete and
-                              self.dependencies.concrete)
+        self._concrete = bool(not self.virtual
+                              and self.namespace is not None
+                              and self.versions.concrete
+                              and self.variants.concrete
+                              and self.architecture
+                              and self.architecture.concrete
+                              and self.compiler and self.compiler.concrete
+                              and self.compiler_flags.concrete
+                              and self.dependencies.concrete)
         return self._concrete
 
     def traverse(self, visited=None, d=0, **kwargs):
@@ -658,7 +725,7 @@ class Spec(object):
                in the traversal.
 
            root     [=True]
-               If false, this won't yield the root node, just its descendents.
+               If False, this won't yield the root node, just its descendents.
 
            direction [=children|parents]
                If 'children', does a traversal of this spec's children.  If
@@ -753,10 +820,10 @@ class Spec(object):
         params.update(dict((name, value)
                       for name, value in self.compiler_flags.items()))
         d = {
-            'parameters': params,
-            'arch': self.architecture,
-            'dependencies': dict((d, self.dependencies[d].dag_hash())
-                                 for d in sorted(self.dependencies)),
+            'parameters' : params,
+            'arch' : self.architecture,
+            'dependencies' : dict((d, self.dependencies[d].dag_hash())
+                                  for d in sorted(self.dependencies))
         }
 
         # Older concrete specs do not have a namespace.  Omit for
@@ -764,6 +831,13 @@ class Spec(object):
         if not self.concrete or self.namespace:
             d['namespace'] = self.namespace
 
+        if self.architecture:
+            # TODO: Fix the target.to_dict to account for the tuple
+            # Want it to be a dict of dicts
+            d['arch'] = self.architecture.to_dict()
+        else:
+            d['arch'] = None
+
         if self.compiler:
             d.update(self.compiler.to_dict())
         else:
@@ -789,11 +863,12 @@ class Spec(object):
         spec = Spec(name)
         spec.namespace = node.get('namespace', None)
         spec.versions = VersionList.from_dict(node)
-        spec.architecture = node['arch']
 
         if 'hash' in node:
             spec._hash = node['hash']
 
+        spec.architecture = spack.architecture.arch_from_dict(node['arch'])
+
         if node['compiler'] is None:
             spec.compiler = None
         else:
@@ -866,12 +941,10 @@ class Spec(object):
 
         # Concretize deps first -- this is a bottom-up process.
         for name in sorted(self.dependencies.keys()):
-            changed |= self.dependencies[
-                name]._concretize_helper(presets, visited)
+            changed |= self.dependencies[name]._concretize_helper(presets, visited)
 
         if self.name in presets:
             changed |= self.constrain(presets[self.name])
-
         else:
             # Concretize virtual dependencies last.  Because they're added
             # to presets below, their constraints will all be merged, but we'll
@@ -936,11 +1009,12 @@ class Spec(object):
         """
         # Make an index of stuff this spec already provides
         self_index = ProviderIndex(self.traverse(), restrict=True)
-
         changed = False
         done = False
+
         while not done:
             done = True
+
             for spec in list(self.traverse()):
                 replacement = None
                 if spec.virtual:
@@ -979,24 +1053,25 @@ class Spec(object):
                             continue
 
                 # If replacement is external then trim the dependencies
-                if replacement.external:
+                if replacement.external or replacement.external_module:
                     if (spec.dependencies):
                         changed = True
                         spec.dependencies = DependencyMap()
                     replacement.dependencies = DependencyMap()
+                    replacement.architecture = self.architecture
 
                 # TODO: could this and the stuff in _dup be cleaned up?
                 def feq(cfield, sfield):
                     return (not cfield) or (cfield == sfield)
 
-                if replacement is spec or (
-                        feq(replacement.name, spec.name) and
-                        feq(replacement.versions, spec.versions) and
-                        feq(replacement.compiler, spec.compiler) and
-                        feq(replacement.architecture, spec.architecture) and
-                        feq(replacement.dependencies, spec.dependencies) and
-                        feq(replacement.variants, spec.variants) and
-                        feq(replacement.external, spec.external)):
+                if replacement is spec or (feq(replacement.name, spec.name) and
+                    feq(replacement.versions, spec.versions) and
+                    feq(replacement.compiler, spec.compiler) and
+                    feq(replacement.architecture, spec.architecture) and
+                    feq(replacement.dependencies, spec.dependencies) and
+                    feq(replacement.variants, spec.variants) and
+                    feq(replacement.external, spec.external) and
+                    feq(replacement.external_module, spec.external_module)):
                     continue
                 # Refine this spec to the candidate. This uses
                 # replace_with AND dup so that it can work in
@@ -1053,6 +1128,15 @@ class Spec(object):
             if s.namespace is None:
                 s.namespace = spack.repo.repo_for_pkg(s.name).namespace
 
+
+        for s in self.traverse(root=False):
+            if s.external_module:
+                compiler = spack.compilers.compiler_for_spec(s.compiler, s.architecture)
+                for mod in compiler.modules:
+                    load_module(mod)
+
+                s.external = get_path_from_module(s.external_module)
+
         # Mark everything in the spec as concrete, as well.
         self._mark_concrete()
 
@@ -1253,7 +1337,7 @@ class Spec(object):
 
         # if we descend into a virtual spec, there's nothing more
         # to normalize.  Concretize will finish resolving it later.
-        if self.virtual or self.external:
+        if self.virtual or self.external or self.external_module:
             return False
 
         # Combine constraints from package deps with constraints from
@@ -1300,7 +1384,6 @@ class Spec(object):
 
         # Ensure first that all packages & compilers in the DAG exist.
         self.validate_names()
-
         # Get all the dependencies into one DependencyMap
         spec_deps = self.flat_dependencies(copy=False)
 
@@ -1378,10 +1461,21 @@ class Spec(object):
                 raise UnsatisfiableVariantSpecError(self.variants[v],
                                                     other.variants[v])
 
+        # TODO: Check out the logic here
         if self.architecture is not None and other.architecture is not None:
-            if self.architecture != other.architecture:
-                raise UnsatisfiableArchitectureSpecError(self.architecture,
-                                                         other.architecture)
+            if self.architecture.platform is not None and other.architecture.platform is not None:
+                if self.architecture.platform != other.architecture.platform:
+                    raise UnsatisfiableArchitectureSpecError(self.architecture,
+                                                             other.architecture)
+            if self.architecture.platform_os is not None and other.architecture.platform_os is not None:
+                if self.architecture.platform_os != other.architecture.platform_os:
+                    raise UnsatisfiableArchitectureSpecError(self.architecture,
+                                                             other.architecture)
+            if self.architecture.target is not None and other.architecture.target is not None:
+                if self.architecture.target != other.architecture.target:
+                    raise UnsatisfiableArchitectureSpecError(self.architecture,
+                                                             other.architecture)
+
 
         changed = False
         if self.compiler is not None and other.compiler is not None:
@@ -1395,9 +1489,17 @@ class Spec(object):
 
         changed |= self.compiler_flags.constrain(other.compiler_flags)
 
-        old = self.architecture
-        self.architecture = self.architecture or other.architecture
-        changed |= (self.architecture != old)
+        old = str(self.architecture)
+        if self.architecture is None or other.architecture is None:
+            self.architecture = self.architecture or other.architecture
+        else:
+            if self.architecture.platform is None or other.architecture.platform is None:
+                self.architecture.platform = self.architecture.platform or other.architecture.platform
+            if self.architecture.platform_os is None or other.architecture.platform_os is None:
+                self.architecture.platform_os = self.architecture.platform_os or other.architecture.platform_os
+            if self.architecture.target is None or other.architecture.target is None:
+                self.architecture.target = self.architecture.target or other.architecture.target
+        changed |= (str(self.architecture) != old)
 
         if deps:
             changed |= self._constrain_dependencies(other)
@@ -1524,9 +1626,14 @@ class Spec(object):
         # Architecture satisfaction is currently just string equality.
         # If not strict, None means unconstrained.
         if self.architecture and other.architecture:
-            if self.architecture != other.architecture:
+            if ((self.architecture.platform and other.architecture.platform and self.architecture.platform != other.architecture.platform) or
+                (self.architecture.platform_os and other.architecture.platform_os and self.architecture.platform_os != other.architecture.platform_os) or
+                (self.architecture.target and other.architecture.target and self.architecture.target != other.architecture.target)):
                 return False
-        elif strict and (other.architecture and not self.architecture):
+        elif strict and ((other.architecture and not self.architecture) or
+                         (other.architecture.platform and not self.architecture.platform) or
+                         (other.architecture.platform_os and not self.architecture.platform_os) or
+                         (other.architecture.target and not self.architecture.target)):
             return False
 
         if not self.compiler_flags.satisfies(
@@ -1601,20 +1708,17 @@ class Spec(object):
 
            Options:
            dependencies[=True]
-               Whether deps should be copied too.  Set to false to copy a
+               Whether deps should be copied too.  Set to False to copy a
                spec but not its dependencies.
         """
         # We don't count dependencies as changes here
         changed = True
         if hasattr(self, 'name'):
-            changed = (self.name != other.name and
-                       self.versions != other.versions and
-                       self.architecture != other.architecture and
-                       self.compiler != other.compiler and
-                       self.variants != other.variants and
-                       self._normal != other._normal and
-                       self.concrete != other.concrete and
-                       self.external != other.external)
+            changed = (self.name != other.name and self.versions != other.versions and \
+                       self.architecture != other.architecture and self.compiler != other.compiler and \
+                       self.variants != other.variants and self._normal != other._normal and \
+                       self.concrete != other.concrete and self.external != other.external and \
+                       self.external_module != other.external_module and self.compiler_flags != other.compiler_flags)
 
         # Local node attributes get copied first.
         self.name = other.name
@@ -1628,6 +1732,7 @@ class Spec(object):
         self.variants = other.variants.copy()
         self.variants.spec = self
         self.external = other.external
+        self.external_module = other.external_module
         self.namespace = other.namespace
         self._hash = other._hash
 
@@ -1648,6 +1753,7 @@ class Spec(object):
         self._normal = other._normal
         self._concrete = other._concrete
         self.external = other.external
+        self.external_module = other.external_module
         return changed
 
     def copy(self, **kwargs):
@@ -1752,6 +1858,7 @@ class Spec(object):
                 self.compiler,
                 self.compiler_flags)
 
+
     def eq_node(self, other):
         """Equality with another spec, not including dependencies."""
         return self._cmp_node() == other._cmp_node()
@@ -1862,7 +1969,7 @@ class Spec(object):
                     if self.variants:
                         write(fmt % str(self.variants), c)
                 elif c == '=':
-                    if self.architecture:
+                    if self.architecture and str(self.architecture):
                         write(fmt % (' arch' + c + str(self.architecture)), c)
                 elif c == '#':
                     out.write('-' + fmt % (self.dag_hash(7)))
@@ -1920,8 +2027,8 @@ class Spec(object):
                     if self.variants:
                         write(fmt % str(self.variants), '+')
                 elif named_str == 'ARCHITECTURE':
-                    if self.architecture:
-                        write(fmt % str(self.architecture), '=')
+                    if self.architecture and str(self.architecture):
+                        write(fmt % str(self.architecture), ' arch=')
                 elif named_str == 'SHA1':
                     if self.dependencies:
                         out.write(fmt % str(self.dag_hash(7)))
@@ -1946,6 +2053,41 @@ class Spec(object):
     def dep_string(self):
         return ''.join("^" + dep.format() for dep in self.sorted_deps())
 
+
+    def __cmp__(self, other):
+        #Package name sort order is not configurable, always goes alphabetical
+        if self.name != other.name:
+            return cmp(self.name, other.name)
+
+        #Package version is second in compare order
+        pkgname = self.name
+        if self.versions != other.versions:
+            return spack.pkgsort.version_compare(pkgname,
+                         self.versions, other.versions)
+
+        #Compiler is third
+        if self.compiler != other.compiler:
+            return spack.pkgsort.compiler_compare(pkgname,
+                         self.compiler, other.compiler)
+
+        #Variants
+        if self.variants != other.variants:
+            return spack.pkgsort.variant_compare(pkgname,
+                         self.variants, other.variants)
+
+        #Target
+        if self.architecture != other.architecture:
+            return spack.pkgsort.architecture_compare(pkgname,
+                         self.architecture, other.architecture)
+
+        #Dependency is not configurable
+        if self.dependencies != other.dependencies:
+            return -1 if self.dependencies < other.dependencies else 1
+
+        #Equal specs
+        return 0
+
+
     def __str__(self):
         return self.format() + self.dep_string()
 
@@ -2015,15 +2157,17 @@ class SpecLexer(spack.parse.Lexer):
             (r'\s+', lambda scanner, val: None)])
 
 
+# Lexer is always the same for every parser.
+_lexer = SpecLexer()
+
 class SpecParser(spack.parse.Parser):
 
     def __init__(self):
-        super(SpecParser, self).__init__(SpecLexer())
+        super(SpecParser, self).__init__(_lexer)
         self.previous = None
 
     def do_parse(self):
         specs = []
-
         try:
             while self.next:
                 # TODO: clean this parsing up a bit
@@ -2067,6 +2211,12 @@ class SpecParser(spack.parse.Parser):
         except spack.parse.ParseError, e:
             raise SpecParseError(e)
 
+
+        # If the spec has an os or a target and no platform, give it the default platform
+        for spec in specs:
+            for s in spec.traverse():
+                if s.architecture.os_string or s.architecture.target_string:
+                    s._set_platform(spack.architecture.sys_type())
         return specs
 
     def parse_compiler(self, text):
@@ -2108,9 +2258,10 @@ class SpecParser(spack.parse.Parser):
         spec.name = spec_name
         spec.versions = VersionList()
         spec.variants = VariantMap(spec)
-        spec.architecture = None
+        spec.architecture = spack.architecture.Arch()
         spec.compiler = None
         spec.external = None
+        spec.external_module = None
         spec.compiler_flags = FlagMap(spec)
         spec.dependents = DependencyMap()
         spec.dependencies = DependencyMap()
@@ -2186,12 +2337,6 @@ class SpecParser(spack.parse.Parser):
             self.check_identifier()
             return self.token.value
 
-    def architecture(self):
-        # TODO: Make this work properly as a subcase of variant (includes
-        # adding names to grammar)
-        self.expect(ID)
-        return self.token.value
-
     def version(self):
         start = None
         end = None
diff --git a/lib/spack/spack/test/__init__.py b/lib/spack/spack/test/__init__.py
index 1668e271fa..fb91f24721 100644
--- a/lib/spack/spack/test/__init__.py
+++ b/lib/spack/spack/test/__init__.py
@@ -31,15 +31,16 @@ from llnl.util.filesystem import join_path
 from llnl.util.tty.colify import colify
 from spack.test.tally_plugin import Tally
 """Names of tests to be included in Spack's test suite"""
-test_names = ['versions', 'url_parse', 'url_substitution', 'packages', 'stage',
+
+test_names = ['architecture', 'versions', 'url_parse', 'url_substitution', 'packages', 'stage',
               'spec_syntax', 'spec_semantics', 'spec_dag', 'concretize',
               'multimethod', 'install', 'package_sanity', 'config',
               'directory_layout', 'pattern', 'python_version', 'git_fetch',
               'svn_fetch', 'hg_fetch', 'mirror', 'modules', 'url_extrapolate',
               'cc', 'link_tree', 'spec_yaml', 'optional_deps',
               'make_executable', 'configure_guess', 'lock', 'database',
-              'namespace_trie', 'yaml', 'sbang', 'environment',
-              'cmd.uninstall', 'cmd.test_install']
+              'namespace_trie', 'yaml', 'sbang', 'environment', 'cmd.find',
+              'cmd.uninstall', 'cmd.test_install', 'cmd.test_compiler_cmd']
 
 
 def list_tests():
diff --git a/lib/spack/spack/test/architecture.py b/lib/spack/spack/test/architecture.py
new file mode 100644
index 0000000000..a6847c5744
--- /dev/null
+++ b/lib/spack/spack/test/architecture.py
@@ -0,0 +1,112 @@
+""" Test checks if the architecture class is created correctly and also that
+    the functions are looking for the correct architecture name
+"""
+import unittest
+import os
+import platform as py_platform
+import spack
+from spack.architecture import *
+from spack.spec import *
+from spack.platforms.cray_xc import CrayXc
+from spack.platforms.linux import Linux
+from spack.platforms.bgq import Bgq
+from spack.platforms.darwin import Darwin
+
+from spack.test.mock_packages_test import *
+
+#class ArchitectureTest(unittest.TestCase):
+class ArchitectureTest(MockPackagesTest):
+
+    def setUp(self):
+        super(ArchitectureTest, self).setUp()
+        self.platform = sys_type()
+
+    def tearDown(self):
+        super(ArchitectureTest, self).tearDown()
+
+    def test_dict_functions_for_architecture(self):
+        arch = Arch()
+        arch.platform = spack.architecture.sys_type()
+        arch.platform_os = arch.platform.operating_system('default_os')
+        arch.target = arch.platform.target('default_target')
+
+        d = arch.to_dict()
+
+        new_arch = spack.architecture.arch_from_dict(d)
+
+        self.assertEqual(arch, new_arch)
+
+        self.assertTrue( isinstance(arch, Arch) )
+        self.assertTrue( isinstance(arch.platform, Platform) )
+        self.assertTrue( isinstance(arch.platform_os, OperatingSystem) )
+        self.assertTrue( isinstance(arch.target, Target) )
+        self.assertTrue( isinstance(new_arch, Arch) )
+        self.assertTrue( isinstance(new_arch.platform, Platform) )
+        self.assertTrue( isinstance(new_arch.platform_os, OperatingSystem) )
+        self.assertTrue( isinstance(new_arch.target, Target) )
+
+
+    def test_sys_type(self):
+        output_platform_class = sys_type()
+        my_arch_class = None
+        if os.path.exists('/opt/cray/craype'):
+            my_platform_class = CrayXc()
+        elif os.path.exists('/bgsys'):
+            my_platform_class = Bgq()
+        elif 'Linux' in py_platform.system():
+            my_platform_class = Linux()
+        elif 'Darwin' in py_platform.system():
+            my_platform_class = Darwin()
+
+        self.assertEqual(str(output_platform_class), str(my_platform_class))
+
+    def test_user_front_end_input(self):
+        """Test when user inputs just frontend that both the frontend target
+            and frontend operating system match
+        """
+        frontend_os = self.platform.operating_system("frontend")
+        frontend_target = self.platform.target("frontend")
+        frontend_spec = Spec("libelf os=frontend target=frontend")
+        frontend_spec.concretize()
+        self.assertEqual(frontend_os, frontend_spec.architecture.platform_os)
+        self.assertEqual(frontend_target, frontend_spec.architecture.target)
+
+    def test_user_back_end_input(self):
+        """Test when user inputs backend that both the backend target and
+            backend operating system match
+        """
+        backend_os = self.platform.operating_system("backend")
+        backend_target = self.platform.target("backend")
+        backend_spec = Spec("libelf os=backend target=backend")
+        backend_spec.concretize()
+        self.assertEqual(backend_os, backend_spec.architecture.platform_os)
+        self.assertEqual(backend_target, backend_spec.architecture.target)
+
+    def test_user_defaults(self):
+        default_os = self.platform.operating_system("default_os")
+        default_target = self.platform.target("default_target")
+
+        default_spec = Spec("libelf") # default is no args
+        default_spec.concretize()
+        self.assertEqual(default_os, default_spec.architecture.platform_os)
+        self.assertEqual(default_target, default_spec.architecture.target)
+
+    def test_user_input_combination(self):
+        os_list = self.platform.operating_sys.keys()
+        target_list = self.platform.targets.keys()
+        additional = ["fe", "be", "frontend", "backend"]
+
+        os_list.extend(additional)
+        target_list.extend(additional)
+
+        combinations = itertools.product(os_list, target_list)
+        results = []
+        for arch in combinations:
+            o,t = arch
+            spec = Spec("libelf os=%s target=%s" % (o, t))
+            spec.concretize()
+            results.append(spec.architecture.platform_os == self.platform.operating_system(o))
+            results.append(spec.architecture.target == self.platform.target(t))
+        res = all(results)
+
+        self.assertTrue(res)
diff --git a/lib/spack/spack/test/cmd/find.py b/lib/spack/spack/test/cmd/find.py
new file mode 100644
index 0000000000..371e9650e0
--- /dev/null
+++ b/lib/spack/spack/test/cmd/find.py
@@ -0,0 +1,60 @@
+##############################################################################
+# Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://github.com/llnl/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License (as
+# published by the Free Software Foundation) version 2.1, February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+
+
+import spack.cmd.find
+import unittest
+
+
+class Bunch(object):
+
+    def __init__(self, **kwargs):
+        self.__dict__.update(kwargs)
+
+
+class FindTest(unittest.TestCase):
+
+    def test_query_arguments(self):
+        query_arguments = spack.cmd.find.query_arguments
+        # Default arguments
+        args = Bunch(only_missing=False, missing=False,
+                     unknown=False, explicit=False, implicit=False)
+        q_args = query_arguments(args)
+        self.assertTrue('installed' in q_args)
+        self.assertTrue('known' in q_args)
+        self.assertTrue('explicit' in q_args)
+        self.assertEqual(q_args['installed'], True)
+        self.assertEqual(q_args['known'], any)
+        self.assertEqual(q_args['explicit'], any)
+        # Check that explicit works correctly
+        args.explicit = True
+        q_args = query_arguments(args)
+        self.assertEqual(q_args['explicit'], True)
+        args.explicit = False
+        args.implicit = True
+        q_args = query_arguments(args)
+        self.assertEqual(q_args['explicit'], False)
+        args.explicit = True
+        self.assertRaises(SystemExit, query_arguments, args)
diff --git a/lib/spack/spack/test/cmd/test_compiler_cmd.py b/lib/spack/spack/test/cmd/test_compiler_cmd.py
new file mode 100644
index 0000000000..d89814154b
--- /dev/null
+++ b/lib/spack/spack/test/cmd/test_compiler_cmd.py
@@ -0,0 +1,81 @@
+import os
+import shutil
+from tempfile import mkdtemp
+
+from llnl.util.filesystem import set_executable, mkdirp
+
+import spack.spec
+import spack.cmd.compiler
+import spack.compilers
+from spack.version import Version
+from spack.test.mock_packages_test import *
+
+test_version = '4.5-spacktest'
+
+class MockArgs(object):
+    def __init__(self, add_paths=[], scope=None, compiler_spec=None, all=None):
+        self.add_paths = add_paths
+        self.scope = scope
+        self.compiler_spec = compiler_spec
+        self.all = all
+
+
+def make_mock_compiler():
+    """Make a directory containing a fake, but detectable compiler."""
+    mock_compiler_dir = mkdtemp()
+    bin_dir = os.path.join(mock_compiler_dir, 'bin')
+    mkdirp(bin_dir)
+
+    gcc_path = os.path.join(bin_dir, 'gcc')
+    gxx_path = os.path.join(bin_dir, 'g++')
+    gfortran_path = os.path.join(bin_dir, 'gfortran')
+
+    with open(gcc_path, 'w') as f:
+        f.write("""\
+#!/bin/sh
+
+for arg in "$@"; do
+    if [ "$arg" = -dumpversion ]; then
+        echo '%s'
+    fi
+done
+""" % test_version)
+
+    # Create some mock compilers in the temporary directory
+    set_executable(gcc_path)
+    shutil.copy(gcc_path, gxx_path)
+    shutil.copy(gcc_path, gfortran_path)
+
+    return mock_compiler_dir
+
+
+class CompilerCmdTest(MockPackagesTest):
+    """ Test compiler commands for add and remove """
+
+
+    def test_compiler_remove(self):
+        args = MockArgs(all=True, compiler_spec='gcc@4.5.0')
+        spack.cmd.compiler.compiler_remove(args)
+        compilers = spack.compilers.all_compilers()
+        self.assertTrue(spack.spec.CompilerSpec("gcc@4.5.0") not in compilers)
+
+
+    def test_compiler_add(self):
+        # compilers available by default.
+        old_compilers = set(spack.compilers.all_compilers())
+
+        # add our new compiler and find again.
+        compiler_dir = make_mock_compiler()
+
+        try:
+            args = MockArgs(add_paths=[compiler_dir])
+            spack.cmd.compiler.compiler_find(args)
+
+            # ensure new compiler is in there
+            new_compilers = set(spack.compilers.all_compilers())
+            new_compiler = new_compilers - old_compilers
+            self.assertTrue(new_compiler)
+            self.assertTrue(new_compiler.pop().version == Version(test_version))
+
+        finally:
+            shutil.rmtree(compiler_dir, ignore_errors=True)
diff --git a/lib/spack/spack/test/concretize.py b/lib/spack/spack/test/concretize.py
index 963481054e..ab201f406a 100644
--- a/lib/spack/spack/test/concretize.py
+++ b/lib/spack/spack/test/concretize.py
@@ -23,6 +23,7 @@
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
 import spack
+import spack.architecture
 from spack.spec import Spec, CompilerSpec
 from spack.version import ver
 from spack.concretize import find_spec
@@ -253,6 +254,19 @@ class ConcretizeTest(MockPackagesTest):
         self.assertTrue(spec['externaltool'].compiler.satisfies('gcc'))
 
 
+    def test_external_package_module(self):
+        # No tcl modules on darwin/linux machines
+        # TODO: improved way to check for this.
+        if (spack.architecture.sys_type().name == 'darwin' or
+            spack.architecture.sys_type().name == 'linux'):
+            return
+
+        spec = Spec('externalmodule')
+        spec.concretize()
+        self.assertEqual(spec['externalmodule'].external_module, 'external-module')
+        self.assertFalse('externalprereq' in spec)
+        self.assertTrue(spec['externalmodule'].compiler.satisfies('gcc'))
+
     def test_nobuild_package(self):
         got_error = False
         spec = Spec('externaltool%clang')
diff --git a/lib/spack/spack/test/config.py b/lib/spack/spack/test/config.py
index eff482f4c6..252d77e66b 100644
--- a/lib/spack/spack/test/config.py
+++ b/lib/spack/spack/test/config.py
@@ -32,45 +32,75 @@ from ordereddict_backport import OrderedDict
 from spack.test.mock_packages_test import *
 
 # Some sample compiler config data
-a_comps =  {
-    "x86_64_E5v2_IntelIB": {
-        "gcc@4.7.3" : {
+a_comps =  [
+    {'compiler': {
+        'paths': {
             "cc" : "/gcc473",
             "cxx": "/g++473",
             "f77": None,
-            "fc" : None },
-        "gcc@4.5.0" : {
+            "fc" : None 
+            },
+        'modules': None,
+        'spec': 'gcc@4.7.3',
+        'operating_system': 'CNL10'
+        }},
+    {'compiler': {
+        'paths': {
             "cc" : "/gcc450",
             "cxx": "/g++450",
-            "f77": "/gfortran",
-            "fc" : "/gfortran" },
-        "clang@3.3"  : {
+            "f77": 'gfortran',
+            "fc" : 'gfortran'
+            },
+        'modules': None,
+        'spec': 'gcc@4.5.0',
+        'operating_system': 'CNL10'
+        }},
+    {'compiler': {
+        'paths': {
             "cc" : "<overwritten>",
             "cxx": "<overwritten>",
-            "f77": "<overwritten>",
-            "fc" : "<overwritten>" }
-    }
-}
-
-b_comps = {
-    "x86_64_E5v3": {
-        "icc@10.0" : {
+            "f77": '<overwritten>',
+            "fc" : '<overwritten>' },
+        'modules': None,
+        'spec': 'clang@3.3',
+        'operating_system': 'CNL10'
+        }}
+]
+
+b_comps = [
+    {'compiler': {
+        'paths': {
             "cc" : "/icc100",
-            "cxx": "/icc100",
+            "cxx": "/icp100",
             "f77": None,
-            "fc" : None },
-        "icc@11.1" : {
+            "fc" : None
+            },
+        'modules': None,
+        'spec': 'icc@10.0',
+        'operating_system': 'CNL10'
+        }},
+    {'compiler': {
+        'paths': {
             "cc" : "/icc111",
             "cxx": "/icp111",
-            "f77": "/ifort",
-            "fc" : "/ifort" },
-        "clang@3.3" : {
-            "cc" : "/clang",
-            "cxx": "/clang++",
-            "f77": None,
-            "fc" : None}
-    }
-}
+            "f77": 'ifort',
+            "fc" : 'ifort'
+            },
+        'modules': None,
+        'spec': 'icc@11.1',
+        'operating_system': 'CNL10'
+        }},
+    {'compiler': {
+        'paths': {
+            "cc" : "<overwritten>",
+            "cxx": "<overwritten>",
+            "f77": '<overwritten>',
+            "fc" : '<overwritten>' },
+        'modules': None,
+        'spec': 'clang@3.3',
+        'operating_system': 'CNL10'
+        }}
+]
 
 # Some Sample repo data
 repos_low = [ "/some/path" ]
@@ -89,15 +119,28 @@ class ConfigTest(MockPackagesTest):
         super(ConfigTest, self).tearDown()
         shutil.rmtree(self.tmp_dir, True)
 
-    def check_config(self, comps, arch, *compiler_names):
+
+    def check_config(self, comps, *compiler_names):
         """Check that named compilers in comps match Spack's config."""
         config = spack.config.get_config('compilers')
         compiler_list = ['cc', 'cxx', 'f77', 'fc']
-        for key in compiler_names:
-            for c in compiler_list:
-                expected = comps[arch][key][c]
-                actual = config[arch][key][c]
-                self.assertEqual(expected, actual)
+        param_list = ['modules', 'paths', 'spec', 'operating_system']
+        for compiler in config:
+            conf = compiler['compiler']
+            if conf['spec'] in compiler_names:
+                comp = None
+                for c in comps:
+                    if c['compiler']['spec'] == conf['spec']:
+                        comp = c['compiler']
+                        break
+                if not comp:
+                    self.fail('Bad config spec')
+                for p in param_list:
+                    self.assertEqual(conf[p], comp[p])
+                for c in compiler_list:
+                    expected = comp['paths'][c]
+                    actual = conf['paths'][c]
+                    self.assertEqual(expected, actual)
 
     def test_write_list_in_memory(self):
         spack.config.update_config('repos', repos_low, 'test_low_priority')
@@ -111,8 +154,9 @@ class ConfigTest(MockPackagesTest):
         spack.config.update_config('compilers', b_comps, 'test_high_priority')
 
         # Make sure the config looks how we expect.
-        self.check_config(a_comps, 'x86_64_E5v2_IntelIB', 'gcc@4.7.3', 'gcc@4.5.0')
-        self.check_config(b_comps, 'x86_64_E5v3', 'icc@10.0', 'icc@11.1', 'clang@3.3')
+        self.check_config(a_comps, 'gcc@4.7.3', 'gcc@4.5.0')
+        self.check_config(b_comps, 'icc@10.0', 'icc@11.1', 'clang@3.3')
+
 
     def test_write_key_to_disk(self):
         # Write b_comps "on top of" a_comps.
@@ -123,8 +167,8 @@ class ConfigTest(MockPackagesTest):
         spack.config.clear_config_caches()
 
         # Same check again, to ensure consistency.
-        self.check_config(a_comps, 'x86_64_E5v2_IntelIB', 'gcc@4.7.3', 'gcc@4.5.0')
-        self.check_config(b_comps, 'x86_64_E5v3', 'icc@10.0', 'icc@11.1', 'clang@3.3')
+        self.check_config(a_comps, 'gcc@4.7.3', 'gcc@4.5.0')
+        self.check_config(b_comps, 'icc@10.0', 'icc@11.1', 'clang@3.3')
 
     def test_write_to_same_priority_file(self):
         # Write b_comps in the same file as a_comps.
@@ -135,5 +179,5 @@ class ConfigTest(MockPackagesTest):
         spack.config.clear_config_caches()
 
         # Same check again, to ensure consistency.
-        self.check_config(a_comps, 'x86_64_E5v2_IntelIB', 'gcc@4.7.3', 'gcc@4.5.0')
-        self.check_config(b_comps, 'x86_64_E5v3', 'icc@10.0', 'icc@11.1', 'clang@3.3')
+        self.check_config(a_comps, 'gcc@4.7.3', 'gcc@4.5.0')
+        self.check_config(b_comps, 'icc@10.0', 'icc@11.1', 'clang@3.3')
diff --git a/lib/spack/spack/test/environment.py b/lib/spack/spack/test/environment.py
index ded1539e18..a0d959db2f 100644
--- a/lib/spack/spack/test/environment.py
+++ b/lib/spack/spack/test/environment.py
@@ -24,17 +24,20 @@
 ##############################################################################
 import unittest
 import os
+import copy
 from spack.environment import EnvironmentModifications
 
 
 class EnvironmentTest(unittest.TestCase):
     def setUp(self):
-        os.environ.clear()
         os.environ['UNSET_ME'] = 'foo'
         os.environ['EMPTY_PATH_LIST'] = ''
         os.environ['PATH_LIST'] = '/path/second:/path/third'
         os.environ['REMOVE_PATH_LIST'] = '/a/b:/duplicate:/a/c:/remove/this:/a/d:/duplicate/:/f/g'
 
+    def tearDown(self):
+        pass
+
     def test_set(self):
         env = EnvironmentModifications()
         env.set('A', 'dummy value')
diff --git a/lib/spack/spack/test/mock_packages_test.py b/lib/spack/spack/test/mock_packages_test.py
index 595667bf35..a56bd8ebdc 100644
--- a/lib/spack/spack/test/mock_packages_test.py
+++ b/lib/spack/spack/test/mock_packages_test.py
@@ -34,20 +34,127 @@ from ordereddict_backport import OrderedDict
 from spack.repository import RepoPath
 from spack.spec import Spec
 
+platform = spack.architecture.sys_type()
+
+linux_os_name = 'debian'
+linux_os_version = '6'
+
+if platform.name == 'linux':
+    linux_os = platform.operating_system("default_os")
+    linux_os_name = linux_os.name
+    linux_os_version = linux_os.version
+
 mock_compiler_config = """\
 compilers:
-  all:
-    clang@3.3:
+- compiler:
+    spec: clang@3.3
+    operating_system: {0}{1}
+    paths:
       cc: /path/to/clang
       cxx: /path/to/clang++
       f77: None
       fc: None
-    gcc@4.5.0:
+    modules: 'None'
+- compiler:
+    spec: gcc@4.5.0  
+    operating_system: {0}{1}
+    paths:
+      cc: /path/to/gcc
+      cxx: /path/to/g++
+      f77: None
+      fc: None
+    modules: 'None'
+- compiler:
+    spec: clang@3.3
+    operating_system: CNL10
+    paths:
+      cc: /path/to/clang
+      cxx: /path/to/clang++
+      f77: None
+      fc: None
+    modules: 'None'
+- compiler:
+    spec: clang@3.3
+    operating_system: SuSE11
+    paths:
+      cc: /path/to/clang
+      cxx: /path/to/clang++
+      f77: None
+      fc: None
+    modules: 'None'
+- compiler:
+    spec: clang@3.3
+    operating_system: redhat6
+    paths:
+      cc: /path/to/clang
+      cxx: /path/to/clang++
+      f77: None
+      fc: None
+    modules: 'None'
+- compiler:
+    spec: clang@3.3
+    operating_system: yosemite
+    paths:
+      cc: /path/to/clang
+      cxx: /path/to/clang++
+      f77: None
+      fc: None
+    modules: 'None'
+- compiler:
+    paths:
       cc: /path/to/gcc
       cxx: /path/to/g++
       f77: /path/to/gfortran
       fc: /path/to/gfortran
-"""
+    operating_system: CNL10
+    spec: gcc@4.5.0
+    modules: 'None'
+- compiler:
+    paths:
+      cc: /path/to/gcc
+      cxx: /path/to/g++
+      f77: /path/to/gfortran
+      fc: /path/to/gfortran
+    operating_system: SuSE11
+    spec: gcc@4.5.0
+    modules: 'None'
+- compiler:
+    paths:
+      cc: /path/to/gcc
+      cxx: /path/to/g++
+      f77: /path/to/gfortran
+      fc: /path/to/gfortran
+    operating_system: redhat6
+    spec: gcc@4.5.0
+    modules: 'None'
+- compiler:
+    paths:
+      cc: /path/to/gcc
+      cxx: /path/to/g++
+      f77: /path/to/gfortran
+      fc: /path/to/gfortran
+    operating_system: yosemite
+    spec: gcc@4.5.0
+    modules: 'None'
+- compiler:
+    paths:
+      cc: /path/to/gcc
+      cxx: /path/to/g++
+      f77: /path/to/gfortran
+      fc: /path/to/gfortran
+    operating_system: elcapitan
+    spec: gcc@4.5.0
+    modules: 'None' 
+- compiler:
+    spec: clang@3.3
+    operating_system: elcapitan
+    paths:
+      cc: /path/to/clang
+      cxx: /path/to/clang++
+      f77: None
+      fc: None
+    modules: 'None'
+""".format(linux_os_name, linux_os_version)
 
 mock_packages_config = """\
 packages:
@@ -60,6 +167,10 @@ packages:
     paths:
       externalvirtual@2.0%clang@3.3: /path/to/external_virtual_clang
       externalvirtual@1.0%gcc@4.5.0: /path/to/external_virtual_gcc
+  externalmodule:
+    buildable: False
+    modules:
+      externalmodule@1.0%gcc@4.5.0: external-module
 """
 
 class MockPackagesTest(unittest.TestCase):
diff --git a/lib/spack/spack/test/modules.py b/lib/spack/spack/test/modules.py
index c73badf8f2..582e067860 100644
--- a/lib/spack/spack/test/modules.py
+++ b/lib/spack/spack/test/modules.py
@@ -73,7 +73,7 @@ configuration_alter_environment = {
         'all': {
             'filter': {'environment_blacklist': ['CMAKE_PREFIX_PATH']}
         },
-        'arch=x86-linux': {
+        'platform=test target=x86_64': {
             'environment': {'set': {'FOO': 'foo'},
                             'unset': ['BAR']}
         }
@@ -116,6 +116,7 @@ class TclTests(MockPackagesTest):
 
     def get_modulefile_content(self, spec):
         spec.concretize()
+        print spec, '&&&&&'
         generator = spack.modules.TclModule(spec)
         generator.write()
         content = FILE_REGISTRY[generator.file_name].split('\n')
@@ -123,27 +124,28 @@ class TclTests(MockPackagesTest):
 
     def test_simple_case(self):
         spack.modules.CONFIGURATION = configuration_autoload_direct
-        spec = spack.spec.Spec('mpich@3.0.4 arch=x86-linux')
+        spec = spack.spec.Spec('mpich@3.0.4')
         content = self.get_modulefile_content(spec)
         self.assertTrue('module-whatis "mpich @3.0.4"' in content)
 
     def test_autoload(self):
         spack.modules.CONFIGURATION = configuration_autoload_direct
-        spec = spack.spec.Spec('mpileaks arch=x86-linux')
+        spec = spack.spec.Spec('mpileaks')
         content = self.get_modulefile_content(spec)
         self.assertEqual(len([x for x in content if 'is-loaded' in x]), 2)
         self.assertEqual(len([x for x in content if 'module load ' in x]), 2)
 
         spack.modules.CONFIGURATION = configuration_autoload_all
-        spec = spack.spec.Spec('mpileaks arch=x86-linux')
+        spec = spack.spec.Spec('mpileaks')
         content = self.get_modulefile_content(spec)
         self.assertEqual(len([x for x in content if 'is-loaded' in x]), 5)
         self.assertEqual(len([x for x in content if 'module load ' in x]), 5)
 
     def test_alter_environment(self):
         spack.modules.CONFIGURATION = configuration_alter_environment
-        spec = spack.spec.Spec('mpileaks arch=x86-linux')
+        spec = spack.spec.Spec('mpileaks platform=test target=x86_64')
         content = self.get_modulefile_content(spec)
+        print content
         self.assertEqual(
             len([x
                  for x in content
@@ -152,8 +154,9 @@ class TclTests(MockPackagesTest):
             len([x for x in content if 'setenv FOO "foo"' in x]), 1)
         self.assertEqual(len([x for x in content if 'unsetenv BAR' in x]), 1)
 
-        spec = spack.spec.Spec('libdwarf arch=x64-linux')
+        spec = spack.spec.Spec('libdwarf %clang platform=test target=x86_32')
         content = self.get_modulefile_content(spec)
+        print content
         self.assertEqual(
             len([x
                  for x in content
@@ -164,14 +167,14 @@ class TclTests(MockPackagesTest):
 
     def test_blacklist(self):
         spack.modules.CONFIGURATION = configuration_blacklist
-        spec = spack.spec.Spec('mpileaks arch=x86-linux')
+        spec = spack.spec.Spec('mpileaks')
         content = self.get_modulefile_content(spec)
         self.assertEqual(len([x for x in content if 'is-loaded' in x]), 1)
         self.assertEqual(len([x for x in content if 'module load ' in x]), 1)
 
     def test_conflicts(self):
         spack.modules.CONFIGURATION = configuration_conflicts
-        spec = spack.spec.Spec('mpileaks arch=x86-linux')
+        spec = spack.spec.Spec('mpileaks')
         content = self.get_modulefile_content(spec)
         self.assertEqual(
             len([x for x in content if x.startswith('conflict')]), 2)
diff --git a/lib/spack/spack/test/multimethod.py b/lib/spack/spack/test/multimethod.py
index a33656adcc..034e6b3923 100644
--- a/lib/spack/spack/test/multimethod.py
+++ b/lib/spack/spack/test/multimethod.py
@@ -92,21 +92,18 @@ class MultiMethodTest(MockPackagesTest):
         self.assertEqual(pkg.has_a_default(), 'default')
 
 
-    def test_architecture_match(self):
-        pkg = spack.repo.get('multimethod arch=x86_64')
-        self.assertEqual(pkg.different_by_architecture(), 'x86_64')
-
-        pkg = spack.repo.get('multimethod arch=ppc64')
-        self.assertEqual(pkg.different_by_architecture(), 'ppc64')
-
-        pkg = spack.repo.get('multimethod arch=ppc32')
-        self.assertEqual(pkg.different_by_architecture(), 'ppc32')
-
-        pkg = spack.repo.get('multimethod arch=arm64')
-        self.assertEqual(pkg.different_by_architecture(), 'arm64')
-
-        pkg = spack.repo.get('multimethod arch=macos')
-        self.assertRaises(NoSuchMethodError, pkg.different_by_architecture)
+    def test_target_match(self):
+        platform = spack.architecture.sys_type()
+        targets = platform.targets.values()
+        for target in targets[:-1]:
+            pkg = spack.repo.get('multimethod target='+target.name)
+            self.assertEqual(pkg.different_by_target(), target.name)
+
+        pkg = spack.repo.get('multimethod target='+targets[-1].name)
+        if len(targets) == 1:
+            self.assertEqual(pkg.different_by_target(), targets[-1].name)
+        else:
+            self.assertRaises(NoSuchMethodError, pkg.different_by_target)
 
 
     def test_dependency_match(self):
diff --git a/lib/spack/spack/test/operating_system.py b/lib/spack/spack/test/operating_system.py
new file mode 100644
index 0000000000..ed5f6ff8ad
--- /dev/null
+++ b/lib/spack/spack/test/operating_system.py
@@ -0,0 +1,55 @@
+""" Test checks if the operating_system class is created correctly and that
+the functions are using the correct operating_system. Also checks whether
+the operating_system correctly uses the compiler_strategy
+"""
+
+import unittest
+import os
+import platform
+from spack.platforms.cray_xc import CrayXc
+from spack.platforms.linux import Linux
+from spack.platforms.darwin import Darwin
+from spack.operating_system.linux_distro import LinuxDistro
+from spack.operating_system.mac_os import MacOs
+from spack.operating_system.cnl import ComputeNodeLinux
+
+class TestOperatingSystem(unittest.TestCase):
+
+    def setUp(self):
+        cray_xc = CrayXc()
+        linux   = Linux()
+        darwin  = Darwin()
+        self.cray_operating_sys = cray_xc.operating_system('front_os')
+        self.cray_default_os = cray_xc.operating_system('default_os')
+        self.cray_back_os = cray_xc.operating_system('back_os')
+        self.darwin_operating_sys = darwin.operating_system('default_os')
+        self.linux_operating_sys  = linux.operating_system('default_os')
+
+    def test_cray_front_end_operating_system(self):
+        self.assertIsInstance(self.cray_operating_sys, LinuxDistro)
+
+    def test_cray_front_end_compiler_strategy(self):
+        self.assertEquals(self.cray_operating_sys.compiler_strategy, "PATH")
+
+    def test_cray_back_end_operating_system(self):
+        self.assertIsInstance(self.cray_back_os,ComputeNodeLinux)
+
+    def test_cray_back_end_compiler_strategy(self):
+        self.assertEquals(self.cray_back_os.compiler_strategy, "MODULES")
+
+    def test_linux_operating_system(self):
+        self.assertIsInstance(self.linux_operating_sys, LinuxDistro)
+
+    def test_linux_compiler_strategy(self):
+        self.assertEquals(self.linux_operating_sys.compiler_strategy, "PATH")
+
+
+    def test_cray_front_end_compiler_list(self):
+        """ Operating systems will now be in charge of finding compilers.
+            So, depending on which operating system you want to build for
+            or which operating system you are on, then you could detect
+            compilers in a certain way. Cray linux environment on the front
+            end is just a regular linux distro whereas the Cray linux compute
+            node is a stripped down version which modules are important
+        """
+        self.assertEquals(True, False)
diff --git a/lib/spack/spack/test/spec_dag.py b/lib/spack/spack/test/spec_dag.py
index 52f4f7395e..712f07ac4d 100644
--- a/lib/spack/spack/test/spec_dag.py
+++ b/lib/spack/spack/test/spec_dag.py
@@ -29,6 +29,7 @@ You can find the dummy packages here::
     spack/lib/spack/spack/test/mock_packages
 """
 import spack
+import spack.architecture
 import spack.package
 
 from llnl.util.lang import list_modules
@@ -241,8 +242,10 @@ class SpecDagTest(MockPackagesTest):
 
 
     def test_unsatisfiable_architecture(self):
-        self.set_pkg_dep('mpileaks', 'mpich arch=bgqos_0')
-        spec = Spec('mpileaks ^mpich arch=sles_10_ppc64 ^callpath ^dyninst ^libelf ^libdwarf')
+        platform = spack.architecture.sys_type()
+
+        self.set_pkg_dep('mpileaks', 'mpich platform=test target=be')
+        spec = Spec('mpileaks ^mpich platform=test target=fe ^callpath ^dyninst ^libelf ^libdwarf')
         self.assertRaises(spack.spec.UnsatisfiableArchitectureSpecError, spec.normalize)
 
 
diff --git a/lib/spack/spack/test/spec_semantics.py b/lib/spack/spack/test/spec_semantics.py
index 0cb78b90ed..9876bfd5a8 100644
--- a/lib/spack/spack/test/spec_semantics.py
+++ b/lib/spack/spack/test/spec_semantics.py
@@ -23,6 +23,7 @@
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
 import unittest
+import spack.architecture
 from spack.spec import *
 from spack.test.mock_packages_test import *
 
@@ -107,7 +108,8 @@ class SpecSematicsTest(MockPackagesTest):
 
 
     def test_satisfies_namespaced_dep(self):
-        """Ensure spec from same or unspecified namespace satisfies namespace constraint."""
+        """Ensure spec from same or unspecified namespace satisfies namespace
+           constraint."""
         self.check_satisfies('mpileaks ^builtin.mock.mpich', '^mpich')
 
         self.check_satisfies('mpileaks ^builtin.mock.mpich', '^mpi')
@@ -139,11 +141,16 @@ class SpecSematicsTest(MockPackagesTest):
 
 
     def test_satisfies_architecture(self):
-        self.check_satisfies('foo arch=chaos_5_x86_64_ib', ' arch=chaos_5_x86_64_ib')
-        self.check_satisfies('foo arch=bgqos_0', ' arch=bgqos_0')
-
-        self.check_unsatisfiable('foo arch=bgqos_0', ' arch=chaos_5_x86_64_ib')
-        self.check_unsatisfiable('foo arch=chaos_5_x86_64_ib', ' arch=bgqos_0')
+        platform = spack.architecture.sys_type()
+        self.check_satisfies(
+            'foo platform=test target=frontend os=frontend',
+            'platform=test target=frontend os=frontend')
+        self.check_satisfies(
+            'foo platform=test target=backend os=backend',
+            'platform=test target=backend', 'platform=test os=backend')
+        self.check_satisfies(
+            'foo platform=test target=default_target os=default_os',
+            'platform=test target=default_target os=default_os')
 
 
     def test_satisfies_dependencies(self):
@@ -158,10 +165,14 @@ class SpecSematicsTest(MockPackagesTest):
         self.check_satisfies('mpileaks^mpich@2.0', '^mpich@1:3')
         self.check_unsatisfiable('mpileaks^mpich@1.2', '^mpich@2.0')
 
-        self.check_satisfies('mpileaks^mpich@2.0^callpath@1.5', '^mpich@1:3^callpath@1.4:1.6')
-        self.check_unsatisfiable('mpileaks^mpich@4.0^callpath@1.5', '^mpich@1:3^callpath@1.4:1.6')
-        self.check_unsatisfiable('mpileaks^mpich@2.0^callpath@1.7', '^mpich@1:3^callpath@1.4:1.6')
-        self.check_unsatisfiable('mpileaks^mpich@4.0^callpath@1.7', '^mpich@1:3^callpath@1.4:1.6')
+        self.check_satisfies(
+            'mpileaks^mpich@2.0^callpath@1.5', '^mpich@1:3^callpath@1.4:1.6')
+        self.check_unsatisfiable(
+            'mpileaks^mpich@4.0^callpath@1.5', '^mpich@1:3^callpath@1.4:1.6')
+        self.check_unsatisfiable(
+            'mpileaks^mpich@2.0^callpath@1.7', '^mpich@1:3^callpath@1.4:1.6')
+        self.check_unsatisfiable(
+            'mpileaks^mpich@4.0^callpath@1.7', '^mpich@1:3^callpath@1.4:1.6')
 
 
     def test_satisfies_virtual_dependencies(self):
@@ -350,10 +361,13 @@ class SpecSematicsTest(MockPackagesTest):
         self.check_constrain('libelf cflags="-O3" cppflags="-Wall"', 'libelf cflags="-O3"', 'libelf cflags="-O3" cppflags="-Wall"')
 
 
-    def test_constrain_arch(self):
-        self.check_constrain('libelf arch=bgqos_0', 'libelf arch=bgqos_0', 'libelf arch=bgqos_0')
-        self.check_constrain('libelf arch=bgqos_0', 'libelf', 'libelf arch=bgqos_0')
-
+    def test_constrain_architecture(self):
+        self.check_constrain('libelf target=default_target os=default_os',
+                             'libelf target=default_target os=default_os',
+                             'libelf target=default_target os=default_os')
+        self.check_constrain('libelf target=default_target os=default_os',
+                             'libelf',
+                             'libelf target=default_target os=default_os')
 
     def test_constrain_compiler(self):
         self.check_constrain('libelf %gcc@4.4.7', 'libelf %gcc@4.4.7', 'libelf %gcc@4.4.7')
@@ -369,9 +383,8 @@ class SpecSematicsTest(MockPackagesTest):
         self.check_invalid_constraint('libelf debug=2', 'libelf debug=1')
 
         self.check_invalid_constraint('libelf cppflags="-O3"', 'libelf cppflags="-O2"')
-
-        self.check_invalid_constraint('libelf arch=bgqos_0', 'libelf arch=x86_54')
-
+        self.check_invalid_constraint('libelf platform=test target=be os=be',
+                                          'libelf target=fe os=fe')
 
     def test_constrain_changed(self):
         self.check_constrain_changed('libelf', '@1.0')
@@ -382,7 +395,10 @@ class SpecSematicsTest(MockPackagesTest):
         self.check_constrain_changed('libelf', '~debug')
         self.check_constrain_changed('libelf', 'debug=2')
         self.check_constrain_changed('libelf', 'cppflags="-O3"')
-        self.check_constrain_changed('libelf', ' arch=bgqos_0')
+
+        platform = spack.architecture.sys_type()
+        self.check_constrain_changed('libelf', 'target='+platform.target('default_target').name)
+        self.check_constrain_changed('libelf', 'os='+platform.operating_system('default_os').name)
 
 
     def test_constrain_not_changed(self):
@@ -395,9 +411,10 @@ class SpecSematicsTest(MockPackagesTest):
         self.check_constrain_not_changed('libelf~debug', '~debug')
         self.check_constrain_not_changed('libelf debug=2', 'debug=2')
         self.check_constrain_not_changed('libelf cppflags="-O3"', 'cppflags="-O3"')
-        self.check_constrain_not_changed('libelf arch=bgqos_0', ' arch=bgqos_0')
-        self.check_constrain_not_changed('libelf^foo', 'libelf^foo')
-        self.check_constrain_not_changed('libelf^foo^bar', 'libelf^foo^bar')
+
+        platform = spack.architecture.sys_type()
+        default_target = platform.target('default_target').name
+        self.check_constrain_not_changed('libelf target='+default_target, 'target='+default_target)
 
 
     def test_constrain_dependency_changed(self):
@@ -407,8 +424,10 @@ class SpecSematicsTest(MockPackagesTest):
         self.check_constrain_changed('libelf^foo%gcc', 'libelf^foo%gcc@4.5')
         self.check_constrain_changed('libelf^foo', 'libelf^foo+debug')
         self.check_constrain_changed('libelf^foo', 'libelf^foo~debug')
-        self.check_constrain_changed('libelf^foo', 'libelf^foo cppflags="-O3"')
-        self.check_constrain_changed('libelf^foo', 'libelf^foo arch=bgqos_0')
+
+        platform = spack.architecture.sys_type()
+        default_target = platform.target('default_target').name
+        self.check_constrain_changed('libelf^foo', 'libelf^foo target='+default_target)
 
 
     def test_constrain_dependency_not_changed(self):
@@ -419,5 +438,7 @@ class SpecSematicsTest(MockPackagesTest):
         self.check_constrain_not_changed('libelf^foo+debug', 'libelf^foo+debug')
         self.check_constrain_not_changed('libelf^foo~debug', 'libelf^foo~debug')
         self.check_constrain_not_changed('libelf^foo cppflags="-O3"', 'libelf^foo cppflags="-O3"')
-        self.check_constrain_not_changed('libelf^foo arch=bgqos_0', 'libelf^foo arch=bgqos_0')
 
+        platform = spack.architecture.sys_type()
+        default_target = platform.target('default_target').name
+        self.check_constrain_not_changed('libelf^foo target='+default_target, 'libelf^foo target='+default_target)
diff --git a/lib/spack/spack/test/spec_syntax.py b/lib/spack/spack/test/spec_syntax.py
index c4e4c9cdfe..4a534d7b5c 100644
--- a/lib/spack/spack/test/spec_syntax.py
+++ b/lib/spack/spack/test/spec_syntax.py
@@ -58,7 +58,7 @@ class SpecSyntaxTest(unittest.TestCase):
     # ================================================================================
     # Parse checks
     # ================================================================================
-    def check_parse(self, expected, spec=None):
+    def check_parse(self, expected, spec=None, remove_arch=True):
         """Assert that the provided spec is able to be parsed.
            If this is called with one argument, it assumes that the string is
            canonical (i.e., no spaces and ~ instead of - for variants) and that it
@@ -70,6 +70,7 @@ class SpecSyntaxTest(unittest.TestCase):
         if spec is None:
             spec = expected
         output = spack.spec.parse(spec)
+
         parsed = (" ".join(str(spec) for spec in output))
         self.assertEqual(expected, parsed)
 
diff --git a/lib/spack/spack/test/versions.py b/lib/spack/spack/test/versions.py
index a026403e2e..4624f901c8 100644
--- a/lib/spack/spack/test/versions.py
+++ b/lib/spack/spack/test/versions.py
@@ -43,7 +43,6 @@ class VersionsTest(unittest.TestCase):
         self.assertFalse(a > b)
         self.assertFalse(a >= b)
 
-
     def assert_ver_gt(self, a, b):
         a, b = ver(a), ver(b)
         self.assertTrue(a > b)
@@ -53,7 +52,6 @@ class VersionsTest(unittest.TestCase):
         self.assertFalse(a < b)
         self.assertFalse(a <= b)
 
-
     def assert_ver_eq(self, a, b):
         a, b = ver(a), ver(b)
         self.assertFalse(a > b)
@@ -63,55 +61,43 @@ class VersionsTest(unittest.TestCase):
         self.assertFalse(a < b)
         self.assertTrue(a <= b)
 
-
     def assert_in(self, needle, haystack):
         self.assertTrue(ver(needle) in ver(haystack))
 
-
     def assert_not_in(self, needle, haystack):
         self.assertFalse(ver(needle) in ver(haystack))
 
-
     def assert_canonical(self, canonical_list, version_list):
         self.assertEqual(ver(canonical_list), ver(version_list))
 
-
     def assert_overlaps(self, v1, v2):
         self.assertTrue(ver(v1).overlaps(ver(v2)))
 
-
     def assert_no_overlap(self, v1, v2):
         self.assertFalse(ver(v1).overlaps(ver(v2)))
 
-
     def assert_satisfies(self, v1, v2):
         self.assertTrue(ver(v1).satisfies(ver(v2)))
 
-
     def assert_does_not_satisfy(self, v1, v2):
         self.assertFalse(ver(v1).satisfies(ver(v2)))
 
-
     def check_intersection(self, expected, a, b):
         self.assertEqual(ver(expected), ver(a).intersection(ver(b)))
 
-
     def check_union(self, expected, a, b):
         self.assertEqual(ver(expected), ver(a).union(ver(b)))
 
-
     def test_two_segments(self):
         self.assert_ver_eq('1.0', '1.0')
         self.assert_ver_lt('1.0', '2.0')
         self.assert_ver_gt('2.0', '1.0')
 
-
     def test_three_segments(self):
         self.assert_ver_eq('2.0.1', '2.0.1')
         self.assert_ver_lt('2.0',   '2.0.1')
         self.assert_ver_gt('2.0.1', '2.0')
 
-
     def test_alpha(self):
         # TODO: not sure whether I like this.  2.0.1a is *usually*
         # TODO: less than 2.0.1, but special-casing it makes version
@@ -120,7 +106,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_ver_gt('2.0.1a', '2.0.1')
         self.assert_ver_lt('2.0.1',  '2.0.1a')
 
-
     def test_patch(self):
         self.assert_ver_eq('5.5p1',  '5.5p1')
         self.assert_ver_lt('5.5p1',  '5.5p2')
@@ -129,7 +114,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_ver_lt('5.5p1',  '5.5p10')
         self.assert_ver_gt('5.5p10', '5.5p1')
 
-
     def test_num_alpha_with_no_separator(self):
         self.assert_ver_lt('10xyz',   '10.1xyz')
         self.assert_ver_gt('10.1xyz', '10xyz')
@@ -137,7 +121,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_ver_lt('xyz10',   'xyz10.1')
         self.assert_ver_gt('xyz10.1', 'xyz10')
 
-
     def test_alpha_with_dots(self):
         self.assert_ver_eq('xyz.4', 'xyz.4')
         self.assert_ver_lt('xyz.4', '8')
@@ -145,30 +128,25 @@ class VersionsTest(unittest.TestCase):
         self.assert_ver_lt('xyz.4', '2')
         self.assert_ver_gt('2',     'xyz.4')
 
-
     def test_nums_and_patch(self):
         self.assert_ver_lt('5.5p2', '5.6p1')
         self.assert_ver_gt('5.6p1', '5.5p2')
         self.assert_ver_lt('5.6p1', '6.5p1')
         self.assert_ver_gt('6.5p1', '5.6p1')
 
-
     def test_rc_versions(self):
         self.assert_ver_gt('6.0.rc1', '6.0')
         self.assert_ver_lt('6.0',     '6.0.rc1')
 
-
     def test_alpha_beta(self):
         self.assert_ver_gt('10b2', '10a1')
         self.assert_ver_lt('10a2', '10b2')
 
-
     def test_double_alpha(self):
         self.assert_ver_eq('1.0aa', '1.0aa')
         self.assert_ver_lt('1.0a',  '1.0aa')
         self.assert_ver_gt('1.0aa', '1.0a')
 
-
     def test_padded_numbers(self):
         self.assert_ver_eq('10.0001', '10.0001')
         self.assert_ver_eq('10.0001', '10.1')
@@ -176,24 +154,20 @@ class VersionsTest(unittest.TestCase):
         self.assert_ver_lt('10.0001', '10.0039')
         self.assert_ver_gt('10.0039', '10.0001')
 
-
     def test_close_numbers(self):
         self.assert_ver_lt('4.999.9', '5.0')
         self.assert_ver_gt('5.0',     '4.999.9')
 
-
     def test_date_stamps(self):
         self.assert_ver_eq('20101121', '20101121')
         self.assert_ver_lt('20101121', '20101122')
         self.assert_ver_gt('20101122', '20101121')
 
-
     def test_underscores(self):
         self.assert_ver_eq('2_0', '2_0')
         self.assert_ver_eq('2.0', '2_0')
         self.assert_ver_eq('2_0', '2.0')
 
-
     def test_rpm_oddities(self):
         self.assert_ver_eq('1b.fc17', '1b.fc17')
         self.assert_ver_lt('1b.fc17', '1.fc17')
@@ -202,7 +176,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_ver_gt('1g.fc17', '1.fc17')
         self.assert_ver_lt('1.fc17',  '1g.fc17')
 
-
     # Stuff below here is not taken from RPM's tests and is
     # unique to spack
     def test_version_ranges(self):
@@ -214,7 +187,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_ver_lt('1.2:1.4', '1.5:1.6')
         self.assert_ver_gt('1.5:1.6', '1.2:1.4')
 
-
     def test_contains(self):
         self.assert_in('1.3', '1.2:1.4')
         self.assert_in('1.2.5', '1.2:1.4')
@@ -233,7 +205,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_in('1.4.1', '1.2.7:1.4')
         self.assert_not_in('1.4.1', '1.2.7:1.4.0')
 
-
     def test_in_list(self):
         self.assert_in('1.2', ['1.5', '1.2', '1.3'])
         self.assert_in('1.2.5', ['1.5', '1.2:1.3'])
@@ -245,7 +216,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_not_in('1.2.5:1.5', ['1.5', '1.2:1.3'])
         self.assert_not_in('1.1:1.2.5', ['1.5', '1.2:1.3'])
 
-
     def test_ranges_overlap(self):
         self.assert_overlaps('1.2', '1.2')
         self.assert_overlaps('1.2.1', '1.2.1')
@@ -262,7 +232,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_overlaps(':', '1.6:1.9')
         self.assert_overlaps('1.6:1.9', ':')
 
-
     def test_overlap_with_containment(self):
         self.assert_in('1.6.5', '1.6')
         self.assert_in('1.6.5', ':1.6')
@@ -273,7 +242,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_not_in(':1.6', '1.6.5')
         self.assert_in('1.6.5', ':1.6')
 
-
     def test_lists_overlap(self):
         self.assert_overlaps('1.2b:1.7,5', '1.6:1.9,1')
         self.assert_overlaps('1,2,3,4,5', '3,4,5,6,7')
@@ -287,7 +255,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_no_overlap('1,2,3,4,5', '6,7')
         self.assert_no_overlap('1,2,3,4,5', '6:7')
 
-
     def test_canonicalize_list(self):
         self.assert_canonical(['1.2', '1.3', '1.4'],
                               ['1.2', '1.3', '1.3', '1.4'])
@@ -316,7 +283,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_canonical([':'],
                               [':,1.3, 1.3.1,1.3.9,1.4 : 1.5 , 1.3 : 1.4'])
 
-
     def test_intersection(self):
         self.check_intersection('2.5',
                                 '1.0:2.5', '2.5:3.0')
@@ -325,12 +291,11 @@ class VersionsTest(unittest.TestCase):
         self.check_intersection('0:1', ':', '0:1')
 
         self.check_intersection(['1.0', '2.5:2.7'],
-                                ['1.0:2.7'], ['2.5:3.0','1.0'])
+                                ['1.0:2.7'], ['2.5:3.0', '1.0'])
         self.check_intersection(['2.5:2.7'],
-                                ['1.1:2.7'], ['2.5:3.0','1.0'])
+                                ['1.1:2.7'], ['2.5:3.0', '1.0'])
         self.check_intersection(['0:1'], [':'], ['0:1'])
 
-
     def test_intersect_with_containment(self):
         self.check_intersection('1.6.5', '1.6.5', ':1.6')
         self.check_intersection('1.6.5', ':1.6', '1.6.5')
@@ -338,7 +303,6 @@ class VersionsTest(unittest.TestCase):
         self.check_intersection('1.6:1.6.5', ':1.6.5', '1.6')
         self.check_intersection('1.6:1.6.5', '1.6', ':1.6.5')
 
-
     def test_union_with_containment(self):
         self.check_union(':1.6', '1.6.5', ':1.6')
         self.check_union(':1.6', ':1.6', '1.6.5')
@@ -346,8 +310,6 @@ class VersionsTest(unittest.TestCase):
         self.check_union(':1.6', ':1.6.5', '1.6')
         self.check_union(':1.6', '1.6', ':1.6.5')
 
-
-    def test_union_with_containment(self):
         self.check_union(':', '1.0:', ':2.0')
 
         self.check_union('1:4', '1:3', '2:4')
@@ -356,7 +318,6 @@ class VersionsTest(unittest.TestCase):
         # Tests successor/predecessor case.
         self.check_union('1:4', '1:2', '3:4')
 
-
     def test_basic_version_satisfaction(self):
         self.assert_satisfies('4.7.3',   '4.7.3')
 
@@ -372,7 +333,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_does_not_satisfy('4.8',   '4.9')
         self.assert_does_not_satisfy('4',     '4.9')
 
-
     def test_basic_version_satisfaction_in_lists(self):
         self.assert_satisfies(['4.7.3'],   ['4.7.3'])
 
@@ -388,7 +348,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_does_not_satisfy(['4.8'],   ['4.9'])
         self.assert_does_not_satisfy(['4'],     ['4.9'])
 
-
     def test_version_range_satisfaction(self):
         self.assert_satisfies('4.7b6', '4.3:4.7')
         self.assert_satisfies('4.3.0', '4.3:4.7')
@@ -400,7 +359,6 @@ class VersionsTest(unittest.TestCase):
         self.assert_satisfies('4.7b6',        '4.3:4.7')
         self.assert_does_not_satisfy('4.8.0', '4.3:4.7')
 
-
     def test_version_range_satisfaction_in_lists(self):
         self.assert_satisfies(['4.7b6'], ['4.3:4.7'])
         self.assert_satisfies(['4.3.0'], ['4.3:4.7'])
@@ -423,3 +381,11 @@ class VersionsTest(unittest.TestCase):
 
         self.assert_satisfies('4.8.0', '4.2, 4.3:4.8')
         self.assert_satisfies('4.8.2', '4.2, 4.3:4.8')
+
+    def test_formatted_strings(self):
+        versions = '1.2.3', '1_2_3', '1-2-3'
+        for item in versions:
+            v = Version(item)
+            self.assertEqual(v.dotted, '1.2.3')
+            self.assertEqual(v.dashed, '1-2-3')
+            self.assertEqual(v.underscored, '1_2_3')
diff --git a/lib/spack/spack/util/executable.py b/lib/spack/spack/util/executable.py
index 38b778fa00..14b56e8d6c 100644
--- a/lib/spack/spack/util/executable.py
+++ b/lib/spack/spack/util/executable.py
@@ -165,6 +165,7 @@ class Executable(object):
                 raise ProcessError("Command exited with status %d:" %
                                    proc.returncode, cmd_line)
 
+
             if output is str or error is str:
                 result = ''
                 if output is str:
diff --git a/lib/spack/spack/version.py b/lib/spack/spack/version.py
index 247f6d2362..858d581472 100644
--- a/lib/spack/spack/version.py
+++ b/lib/spack/spack/version.py
@@ -43,16 +43,16 @@ be called on any of the types::
   intersection
   concrete
 """
-import os
-import sys
 import re
 from bisect import bisect_left
 from functools import wraps
+
 from functools_backport import total_ordering
 
 # Valid version characters
 VALID_VERSION = r'[A-Za-z0-9_.-]'
 
+
 def int_if_int(string):
     """Convert a string to int if possible.  Otherwise, return a string."""
     try:
@@ -62,10 +62,11 @@ def int_if_int(string):
 
 
 def coerce_versions(a, b):
-    """Convert both a and b to the 'greatest' type between them, in this order:
+    """
+    Convert both a and b to the 'greatest' type between them, in this order:
            Version < VersionRange < VersionList
-       This is used to simplify comparison operations below so that we're always
-       comparing things that are of the same type.
+    This is used to simplify comparison operations below so that we're always
+    comparing things that are of the same type.
     """
     order = (Version, VersionRange, VersionList)
     ta, tb = type(a), type(b)
@@ -105,6 +106,7 @@ def coerced(method):
 @total_ordering
 class Version(object):
     """Class to represent versions"""
+
     def __init__(self, string):
         string = str(string)
 
@@ -124,6 +126,17 @@ class Version(object):
         # last element of separators is ''
         self.separators = tuple(re.split(segment_regex, string)[1:-1])
 
+    @property
+    def dotted(self):
+        return '.'.join(str(x) for x in self.version)
+
+    @property
+    def underscored(self):
+        return '_'.join(str(x) for x in self.version)
+
+    @property
+    def dashed(self):
+        return '-'.join(str(x) for x in self.version)
 
     def up_to(self, index):
         """Return a version string up to the specified component, exclusive.
@@ -131,15 +144,12 @@ class Version(object):
         """
         return '.'.join(str(x) for x in self[:index])
 
-
     def lowest(self):
         return self
 
-
     def highest(self):
         return self
 
-
     @coerced
     def satisfies(self, other):
         """A Version 'satisfies' another if it is at least as specific and has a
@@ -147,11 +157,10 @@ class Version(object):
            gcc@4.7 so that when a user asks to build with gcc@4.7, we can find
            a suitable compiler.
         """
-        nself  = len(self.version)
+        nself = len(self.version)
         nother = len(other.version)
         return nother <= nself and self.version[:nother] == other.version
 
-
     def wildcard(self):
         """Create a regex that will match variants of this version string."""
         def a_or_n(seg):
@@ -181,28 +190,22 @@ class Version(object):
         wc += '(?:[a-z]|alpha|beta)?)?' * (len(segments) - 1)
         return wc
 
-
     def __iter__(self):
         return iter(self.version)
 
-
     def __getitem__(self, idx):
         return tuple(self.version[idx])
 
-
     def __repr__(self):
         return self.string
 
-
     def __str__(self):
         return self.string
 
-
     @property
     def concrete(self):
         return self
 
-
     @coerced
     def __lt__(self, other):
         """Version comparison is designed for consistency with the way RPM
@@ -235,28 +238,23 @@ class Version(object):
         # If the common prefix is equal, the one with more segments is bigger.
         return len(self.version) < len(other.version)
 
-
     @coerced
     def __eq__(self, other):
         return (other is not None and
                 type(other) == Version and self.version == other.version)
 
-
     def __ne__(self, other):
         return not (self == other)
 
-
     def __hash__(self):
         return hash(self.version)
 
-
     @coerced
     def __contains__(self, other):
         if other is None:
             return False
         return other.version[:len(self.version)] == self.version
 
-
     def is_predecessor(self, other):
         """True if the other version is the immediate predecessor of this one.
            That is, NO versions v exist such that:
@@ -269,16 +267,13 @@ class Version(object):
         ol = other.version[-1]
         return type(sl) == int and type(ol) == int and (ol - sl == 1)
 
-
     def is_successor(self, other):
         return other.is_predecessor(self)
 
-
     @coerced
     def overlaps(self, other):
         return self in other or other in self
 
-
     @coerced
     def union(self, other):
         if self == other or other in self:
@@ -288,7 +283,6 @@ class Version(object):
         else:
             return VersionList([self, other])
 
-
     @coerced
     def intersection(self, other):
         if self == other:
@@ -299,6 +293,7 @@ class Version(object):
 
 @total_ordering
 class VersionRange(object):
+
     def __init__(self, start, end):
         if isinstance(start, basestring):
             start = Version(start)
@@ -310,15 +305,12 @@ class VersionRange(object):
         if start and end and end < start:
             raise ValueError("Invalid Version range: %s" % self)
 
-
     def lowest(self):
         return self.start
 
-
     def highest(self):
         return self.end
 
-
     @coerced
     def __lt__(self, other):
         """Sort VersionRanges lexicographically so that they are ordered first
@@ -331,28 +323,24 @@ class VersionRange(object):
 
         s, o = self, other
         if s.start != o.start:
-            return s.start is None or (o.start is not None and s.start < o.start)
+            return s.start is None or (o.start is not None and s.start < o.start)  # NOQA: ignore=E501
 
         return (s.end != o.end and
                 o.end is None or (s.end is not None and s.end < o.end))
 
-
     @coerced
     def __eq__(self, other):
         return (other is not None and
                 type(other) == VersionRange and
                 self.start == other.start and self.end == other.end)
 
-
     def __ne__(self, other):
         return not (self == other)
 
-
     @property
     def concrete(self):
         return self.start if self.start == self.end else None
 
-
     @coerced
     def __contains__(self, other):
         if other is None:
@@ -373,57 +361,55 @@ class VersionRange(object):
                         other.end in self.end)))
         return in_upper
 
-
     @coerced
     def satisfies(self, other):
-        """A VersionRange satisfies another if some version in this range
-           would satisfy some version in the other range.  To do this it must
-           either:
-             a) Overlap with the other range
-             b) The start of this range satisfies the end of the other range.
-
-           This is essentially the same as overlaps(), but overlaps assumes
-           that its arguments are specific.  That is, 4.7 is interpreted as
-           4.7.0.0.0.0... .  This funciton assumes that 4.7 woudl be satisfied
-           by 4.7.3.5, etc.
-
-           Rationale:
-           If a user asks for gcc@4.5:4.7, and a package is only compatible with
-           gcc@4.7.3:4.8, then that package should be able to build under the
-           constraints.  Just using overlaps() would not work here.
-
-           Note that we don't need to check whether the end of this range
-           would satisfy the start of the other range, because overlaps()
-           already covers that case.
-
-           Note further that overlaps() is a symmetric operation, while
-           satisfies() is not.
+        """
+        A VersionRange satisfies another if some version in this range
+        would satisfy some version in the other range.  To do this it must
+        either:
+          a) Overlap with the other range
+          b) The start of this range satisfies the end of the other range.
+
+        This is essentially the same as overlaps(), but overlaps assumes
+        that its arguments are specific.  That is, 4.7 is interpreted as
+        4.7.0.0.0.0... .  This funciton assumes that 4.7 woudl be satisfied
+        by 4.7.3.5, etc.
+
+        Rationale:
+        If a user asks for gcc@4.5:4.7, and a package is only compatible with
+        gcc@4.7.3:4.8, then that package should be able to build under the
+        constraints.  Just using overlaps() would not work here.
+
+        Note that we don't need to check whether the end of this range
+        would satisfy the start of the other range, because overlaps()
+        already covers that case.
+
+        Note further that overlaps() is a symmetric operation, while
+        satisfies() is not.
         """
         return (self.overlaps(other) or
                 # if either self.start or other.end are None, then this can't
                 # satisfy, or overlaps() would've taken care of it.
                 self.start and other.end and self.start.satisfies(other.end))
 
-
     @coerced
     def overlaps(self, other):
-        return ((self.start == None or other.end is None or
+        return ((self.start is None or other.end is None or
                  self.start <= other.end or
                  other.end in self.start or self.start in other.end) and
-                (other.start is None or self.end == None or
+                (other.start is None or self.end is None or
                  other.start <= self.end or
                  other.start in self.end or self.end in other.start))
 
-
     @coerced
     def union(self, other):
         if not self.overlaps(other):
             if (self.end is not None and other.start is not None and
-                self.end.is_predecessor(other.start)):
+                    self.end.is_predecessor(other.start)):
                 return VersionRange(self.start, other.end)
 
             if (other.end is not None and self.start is not None and
-                other.end.is_predecessor(self.start)):
+                    other.end.is_predecessor(self.start)):
                 return VersionRange(other.start, self.end)
 
             return VersionList([self, other])
@@ -442,13 +428,12 @@ class VersionRange(object):
         else:
             end = self.end
             # TODO: See note in intersection() about < and in discrepancy.
-            if not other.end in self.end:
+            if other.end not in self.end:
                 if end in other.end or other.end > self.end:
                     end = other.end
 
         return VersionRange(start, end)
 
-
     @coerced
     def intersection(self, other):
         if self.overlaps(other):
@@ -470,7 +455,7 @@ class VersionRange(object):
                 #     1.6 < 1.6.5  = True  (lexicographic)
                 # Should 1.6 NOT be less than 1.6.5?  Hm.
                 # Here we test (not end in other.end) first to avoid paradox.
-                if other.end is not None and not end in other.end:
+                if other.end is not None and end not in other.end:
                     if other.end < end or other.end in end:
                         end = other.end
 
@@ -479,15 +464,12 @@ class VersionRange(object):
         else:
             return VersionList()
 
-
     def __hash__(self):
         return hash((self.start, self.end))
 
-
     def __repr__(self):
         return self.__str__()
 
-
     def __str__(self):
         out = ""
         if self.start:
@@ -501,6 +483,7 @@ class VersionRange(object):
 @total_ordering
 class VersionList(object):
     """Sorted, non-redundant list of Versions and VersionRanges."""
+
     def __init__(self, vlist=None):
         self.versions = []
         if vlist is not None:
@@ -515,7 +498,6 @@ class VersionList(object):
                 for v in vlist:
                     self.add(ver(v))
 
-
     def add(self, version):
         if type(version) in (Version, VersionRange):
             # This normalizes single-value version ranges.
@@ -524,9 +506,9 @@ class VersionList(object):
 
             i = bisect_left(self, version)
 
-            while i-1 >= 0 and version.overlaps(self[i-1]):
-                version = version.union(self[i-1])
-                del self.versions[i-1]
+            while i - 1 >= 0 and version.overlaps(self[i - 1]):
+                version = version.union(self[i - 1])
+                del self.versions[i - 1]
                 i -= 1
 
             while i < len(self) and version.overlaps(self[i]):
@@ -542,7 +524,6 @@ class VersionList(object):
         else:
             raise TypeError("Can't add %s to VersionList" % type(version))
 
-
     @property
     def concrete(self):
         if len(self) == 1:
@@ -550,11 +531,9 @@ class VersionList(object):
         else:
             return None
 
-
     def copy(self):
         return VersionList(self)
 
-
     def lowest(self):
         """Get the lowest version in the list."""
         if not self:
@@ -562,7 +541,6 @@ class VersionList(object):
         else:
             return self[0].lowest()
 
-
     def highest(self):
         """Get the highest version in the list."""
         if not self:
@@ -570,7 +548,6 @@ class VersionList(object):
         else:
             return self[-1].highest()
 
-
     @coerced
     def overlaps(self, other):
         if not other or not self:
@@ -586,14 +563,12 @@ class VersionList(object):
                 o += 1
         return False
 
-
     def to_dict(self):
         """Generate human-readable dict for YAML."""
         if self.concrete:
-            return { 'version'  : str(self[0]) }
+            return {'version': str(self[0])}
         else:
-            return { 'versions' : [str(v) for v in self] }
-
+            return {'versions': [str(v) for v in self]}
 
     @staticmethod
     def from_dict(dictionary):
@@ -605,7 +580,6 @@ class VersionList(object):
         else:
             raise ValueError("Dict must have 'version' or 'versions' in it.")
 
-
     @coerced
     def satisfies(self, other, strict=False):
         """A VersionList satisfies another if some version in the list
@@ -633,20 +607,17 @@ class VersionList(object):
                 o += 1
         return False
 
-
     @coerced
     def update(self, other):
         for v in other.versions:
             self.add(v)
 
-
     @coerced
     def union(self, other):
         result = self.copy()
         result.update(other)
         return result
 
-
     @coerced
     def intersection(self, other):
         # TODO: make this faster.  This is O(n^2).
@@ -656,7 +627,6 @@ class VersionList(object):
                 result.add(s.intersection(o))
         return result
 
-
     @coerced
     def intersect(self, other):
         """Intersect this spec's list with other.
@@ -678,50 +648,40 @@ class VersionList(object):
             if i == 0:
                 if version not in self[0]:
                     return False
-            elif all(version not in v for v in self[i-1:]):
+            elif all(version not in v for v in self[i - 1:]):
                 return False
 
         return True
 
-
     def __getitem__(self, index):
         return self.versions[index]
 
-
     def __iter__(self):
         return iter(self.versions)
 
-
     def __reversed__(self):
         return reversed(self.versions)
 
-
     def __len__(self):
         return len(self.versions)
 
-
     @coerced
     def __eq__(self, other):
         return other is not None and self.versions == other.versions
 
-
     def __ne__(self, other):
         return not (self == other)
 
-
     @coerced
     def __lt__(self, other):
         return other is not None and self.versions < other.versions
 
-
     def __hash__(self):
         return hash(tuple(self.versions))
 
-
     def __str__(self):
         return ",".join(str(v) for v in self.versions)
 
-
     def __repr__(self):
         return str(self.versions)
 
@@ -730,7 +690,7 @@ def _string_to_version(string):
     """Converts a string to a Version, VersionList, or VersionRange.
        This is private.  Client code should use ver().
     """
-    string = string.replace(' ','')
+    string = string.replace(' ', '')
 
     if ',' in string:
         return VersionList(string.split(','))
@@ -738,7 +698,7 @@ def _string_to_version(string):
     elif ':' in string:
         s, e = string.split(':')
         start = Version(s) if s else None
-        end   = Version(e) if e else None
+        end = Version(e) if e else None
         return VersionRange(start, end)
 
     else:
diff --git a/lib/spack/spack/yaml_version_check.py b/lib/spack/spack/yaml_version_check.py
new file mode 100644
index 0000000000..c2d084d6c3
--- /dev/null
+++ b/lib/spack/spack/yaml_version_check.py
@@ -0,0 +1,55 @@
+##############################################################################
+# Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://github.com/llnl/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License (as
+# published by the Free Software Foundation) version 2.1, February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+"""Yaml Version Check is a module for ensuring that config file
+formats are compatible with the current version of Spack."""
+import os.path
+import os
+import llnl.util.tty as tty
+import spack.util.spack_yaml as syaml
+import spack.config
+
+
+def check_yaml_versions():
+    check_compiler_yaml_version()
+
+def check_compiler_yaml_version():
+    config_scopes = spack.config.config_scopes
+    for scope in config_scopes.values():
+        file_name = os.path.join(scope.path, 'compilers.yaml')
+        data = None
+        if os.path.isfile(file_name):
+            with open(file_name) as f:
+                data = syaml.load(f)
+
+        if data:
+            compilers = data['compilers']
+            if len(compilers) > 0:
+                if (not isinstance(compilers, list)) or 'operating_system' not in compilers[0]['compiler']:
+                    new_file = os.path.join(scope.path, '_old_compilers.yaml')
+                    tty.warn('%s in out of date compilers format. '
+                             'Moved to %s. Spack automatically generate '
+                             'a compilers config file '
+                             % (file_name, new_file))
+                    os.rename(file_name, new_file)