Add libglvnd packages/Add EGL support (#14572)

* add new package: "libglvnd-frontend"

* add +glvnd variant to opengl package

* add +glvnd variant to mesa package

* add +egl variant to paraview package

* add libglvnd-frontend entries to default packages config

* fix style

* add default providers for glvnd virtuals

add default providers for glvnd-gl, glvnd-glx, and glvnd-egl

* WIP: rough start to external OpenGL documentation

* rename libglvnd-frontend package and backend virtual dependencies

* update documentation

* fix ligvnd-be-* typos

* fix libglvnd-fe package class name

* fix doc parse error

6 files changed, 242 insertions, 17 deletions

diff --git a/etc/spack/defaults/packages.yaml b/etc/spack/defaults/packages.yaml
index dcfbf76b51..4e8f002787 100644
--- a/etc/spack/defaults/packages.yaml
+++ b/etc/spack/defaults/packages.yaml
@@ -23,8 +23,12 @@ packages:
       daal: [intel-daal]
       elf: [elfutils]
       fftw-api: [fftw]
-      gl: [mesa+opengl, opengl]
-      glx: [mesa+glx, opengl]
+      gl: [libglvnd-fe, mesa+opengl~glvnd, opengl~glvnd]
+      glx: [libglvnd-fe+glx, mesa+glx~glvnd, opengl+glx~glvnd]
+      egl: [libglvnd-fe+egl, opengl+egl~glvnd]
+      libglvnd-be-gl: [mesa+glvnd, opengl+glvnd]
+      libglvnd-be-glx: [mesa+glx+glvnd, opengl+glx+glvnd]
+      libglvnd-be-egl: [opengl+egl+glvnd]
       glu: [mesa-glu, openglu]
       golang: [gcc]
       iconv: [libiconv]
diff --git a/lib/spack/docs/getting_started.rst b/lib/spack/docs/getting_started.rst
index 7b908465f5..04594d7e6e 100644
--- a/lib/spack/docs/getting_started.rst
+++ b/lib/spack/docs/getting_started.rst
@@ -811,6 +811,100 @@ to add the following to ``packages.yaml``:
    present in PATH, however it will have lower precedence compared to paths
    from other dependencies. This ensures that binaries in Spack dependencies
    are preferred over system binaries.
+   
+^^^^^^
+OpenGL
+^^^^^^
+
+To use hardware-accelerated rendering from a system-supplied OpenGL driver,
+add something like the following to your ``packages`` configuration:
+
+.. code-block:: yaml
+
+    packages:
+        opengl:
+            paths:
+                opengl+glx@4.5: /usr
+            buildable: False
+        all:
+            providers:
+                gl: [opengl]
+                glx: [opengl]
+
+For `EGL <https://www.khronos.org/egl>` support, or for certain modern drivers,
+OpenGL calls are dispatched dynamically at run time to the hardware graphics
+implementation.  This dynamic dispatch is performed using `libglvnd
+<https://github.com/NVIDIA/libglvnd>`.  In this mode, the graphics library
+(e.g.: opengl) must be built to work with libglvnd.  Applications then link
+against libglvnd instead of the underlying implementation.  Environment
+variables set at run time govern the process by which libglvnd loads the
+underlying implementation and dispatches calls to it.  See `this
+<https://github.com/NVIDIA/libglvnd/issues/177#issuecomment-496562769>` comment
+for details on loading a specific GLX implementation and `this
+<https://github.com/NVIDIA/libglvnd/blob/master/src/EGL/icd_enumeration.md>`
+page for information about EGL ICD enumeration.
+
+This codependency between libglvnd and the underlying implementation is modeled
+in Spack with two packages for libglvnd: libglvnd, which provides libglvnd
+proper; and libglvnd-fe, a bundle package that depends on libglvnd and an
+implementation.  Implementations that work through libglvnd are no longer
+providers for graphics virtual dependencies, like "gl" or "glx", but instead
+provide libglvnd versions of these dependencies ("libglvnd-be-gl",
+"libglvnd-be-glx", etc.).  The libglvnd-fe package depends on these
+"libglvnd-be-..." virtual packages, which provide the actual implementation.
+It also depends on libglvnd, itself, and exposes its libraries to downstream
+applications.  For correct operation, the Spack package for the underlying
+implementation has to set the runtime environment to ensure that it is loaded
+when an application linked against libglvnd runs.  This last detail is
+important for users who want to set up an external OpenGL implementation that
+requires libglvnd to work.  This setup requires modifying the ``modules``
+configuration so that modules generated for the external OpenGL implementation
+set the necessary environment variables.
+
+.. code-block:: yaml
+
+    packages:
+        opengl:
+            paths:
+                opengl@4.5+glx+egl+glvnd: /does/not/exist
+            buildable: False
+            variants:+glx+egl+glvnd
+        libglvnd-fe:
+            variants:+gl+glx+egl
+        all:
+            providers:
+                glvnd-be-gl: [opengl]
+                glvnd-be-glx: [opengl]
+                glvnd-be-egl: [opengl]
+                gl: [libglvnd-fe]
+                glx: [libglvnd-fe]
+                egl: [libglvnd-fe]
+      
+.. code-block:: yaml
+
+    modules:
+        tcl:
+          opengl@4.5+glx+glvnd:
+            environment:
+              set:
+                __GLX_VENDOR_LIBRARY_NAME: nvidia
+          opengl@4.5+egl+glvnd:
+            environment:
+              set:
+                __EGL_VENDOR_LIBRARY_FILENAMES: /usr/share/glvnd/egl_vendor.d/10_nvidia.json
+
+One final detail about the above example is that it avoids setting the true
+root of the external OpenGL implementation, instead opting to set it to a path
+that is not expected to exist on the system.  This is done for two reasons.
+First, Spack would add directories under this root to environment variables
+that would affect the process of building and installing other packages, such
+as ``PATH`` and ``PKG_CONFIG_PATH``.  These additions may potentially prevent
+those packages from installing successfully, and this risk is especially great
+for paths that house many libraries and applications, like ``/usr``.  Second,
+providing the true root of the external implementation in the ``packages``
+configuration is not necessary because libglvnd need only the environment
+variables set above in the ``modules`` configuration to determine what OpenGL
+implementation to dispatch calls to at run time.
 
 ^^^
 Git
diff --git a/var/spack/repos/builtin/packages/libglvnd-fe/package.py b/var/spack/repos/builtin/packages/libglvnd-fe/package.py
new file mode 100644
index 0000000000..6f737a9017
--- /dev/null
+++ b/var/spack/repos/builtin/packages/libglvnd-fe/package.py
@@ -0,0 +1,56 @@
+# Copyright 2013-2019 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack import *
+
+
+class LibglvndFe(BundlePackage):
+    """The GL Vendor-Neutral Dispatch library (Frontend Dummy Package)
+
+    libglvnd is a vendor-neutral dispatch layer for arbitrating OpenGL API
+    calls between multiple vendors. It allows multiple drivers from different
+    vendors to coexist on the same filesystem, and determines which vendor to
+    dispatch each API call to at runtime.
+
+    Both GLX and EGL are supported, in any combination with OpenGL and OpenGL
+    ES."""
+
+    homepage = "https://github.com/NVIDIA/libglvnd"
+
+    version('1.1.1', sha256='71918ed1261e4eece18c0b74b50dc62c0237b8d526e83277ef078554544720b9')
+
+    variant('glx', default=False, description='Provide GLX API')
+    variant('egl', default=False, description='Provide EGL API')
+
+    depends_on('libglvnd')
+
+    depends_on('libglvnd-be-gl')
+    depends_on('libglvnd-be-glx', when='+glx')
+    depends_on('libglvnd-be-egl', when='+egl')
+
+    provides('gl')
+    provides('glx', when='+glx')
+    provides('egl', when='+egl')
+
+    @property
+    def gl_libs(self):
+        return find_libraries('libOpenGL',
+                              root=self.spec['libglvnd'].prefix,
+                              shared=True,
+                              recursive=True)
+
+    @property
+    def glx_libs(self):
+        return find_libraries('libGLX',
+                              root=self.spec['libglvnd'].prefix,
+                              shared=True,
+                              recursive=True)
+
+    @property
+    def egl_libs(self):
+        return find_libraries('libEGL',
+                              root=self.spec['libglvnd'].prefix,
+                              shared=True,
+                              recursive=True)
diff --git a/var/spack/repos/builtin/packages/mesa/package.py b/var/spack/repos/builtin/packages/mesa/package.py
index b277a03d19..94b352d8e2 100644
--- a/var/spack/repos/builtin/packages/mesa/package.py
+++ b/var/spack/repos/builtin/packages/mesa/package.py
@@ -65,9 +65,13 @@ class Mesa(AutotoolsPackage):
     variant('opengles', default=False, description="Enable OpenGL ES support.")
 
     # Provides
-    provides('gl@4.5',  when='+opengl')
-    provides('glx@1.4', when='+glx')
-    # provides('egl@1.5', when='+egl')
+    provides('gl@4.5',  when='+opengl ~glvnd')
+    provides('glx@1.4', when='+glx ~glvnd')
+    # provides('egl@1.5', when='+egl ~glvnd')
+
+    provides('libglvnd-be-gl', when='+glvnd')
+    provides('libglvnd-be-glx', when='+glvnd +glx')
+    # provides('libglvnd-be-egl', when='+glvnd +egl')
 
     # Variant dependencies
     depends_on('llvm@6:', when='+llvm')
@@ -179,10 +183,32 @@ class Mesa(AutotoolsPackage):
         return args
 
     @property
-    def libs(self):
-        for dir in ['lib64', 'lib']:
-            libs = find_libraries(['libGL', 'libOSMesa'],
-                                  join_path(self.prefix, dir),
-                                  shared=True, recursive=False)
-            if libs:
-                return libs
+    def gl_libs(self):
+        result = LibraryList(())
+
+        if '~glvnd' in self.spec:
+            result.extend(find_libraries('libGL',
+                                         root=self.spec.prefix,
+                                         shared='+shared' in self.spec,
+                                         recursive=True))
+        return result
+
+    @property
+    def glx_libs(self):
+        result = LibraryList(())
+
+        if '~glvnd' in self.spec:
+            result.extend(find_libraries('libGLX',
+                                         root=self.spec.prefix,
+                                         shared='+shared' in self.spec,
+                                         recursive=True))
+        return result
+
+    def setup_run_environment(self, env):
+        if '+glx +glvnd' in self.spec:
+            env.set('__GLX_VENDOR_LIBRARY_NAME', 'mesa')
+
+        if '+egl +glvnd' in self.spec:
+            env.set('__EGL_VENDOR_LIBRARY_FILENAMES', ':'.join((
+                os.path.join(self.spec.prefix, 'share', 'glvnd',
+                             'egl_vendor.d', '50_mesa.json'))))
diff --git a/var/spack/repos/builtin/packages/opengl/package.py b/var/spack/repos/builtin/packages/opengl/package.py
index 413b8e0f45..572fc04845 100644
--- a/var/spack/repos/builtin/packages/opengl/package.py
+++ b/var/spack/repos/builtin/packages/opengl/package.py
@@ -13,7 +13,14 @@ class Opengl(Package):
 
     homepage = "https://www.opengl.org/"
 
-    provides('gl')
+    variant('glvnd',
+            default=False,
+            description="Expose Graphics APIs through libglvnd")
+
+    variant('glx', default=True, description="Enable GLX API.")
+    variant('egl', default=False, description="Enable EGL API.")
+
+    provides('gl', when='~glvnd')
     provides('gl@:4.5', when='@4.5:')
     provides('gl@:4.4', when='@4.4:')
     provides('gl@:4.3', when='@4.3:')
@@ -33,7 +40,19 @@ class Opengl(Package):
     provides('gl@:1.0', when='@1.0:')
 
     if sys.platform != 'darwin':
-        provides('glx@1.4')
+        provides('glx@1.4', when='~glvnd +glx')
+
+    # NOTE: This package should have a dependency on libglvnd, but because it
+    # is exclusively provided externally the dependency is never traversed.
+    # depends_on('libglvnd', when='+glvnd')  # don't uncomment this
+
+    provides('libglvnd-be-gl', when='+glvnd')
+    provides('libglvnd-be-glx', when='+glvnd +glx')
+    provides('libglvnd-be-egl', when='+glvnd +egl')
+
+    provides('egl@1.5', when='~glvnd +egl')
+
+    depends_on('libglvnd', when='+glvnd')
 
     # Override the fetcher method to throw a useful error message;
     # fixes GitHub issue (#7061) in which this package threw a
@@ -80,8 +99,25 @@ class Opengl(Package):
 
     @property
     def libs(self):
+        result = LibraryList(())
+
+        # "libs" provided by glvnd; this package sets the environment variables
+        # so that glvnd, in turn, loads this package's libraries at run-time.
+        if '+glvnd' in self.spec:
+            return result
+
         for dir in ['lib64', 'lib']:
             libs = find_libraries('libGL', join_path(self.prefix, dir),
                                   shared=True, recursive=False)
             if libs:
-                return libs
+                result.extend(libs)
+                break
+
+        if '+egl' in self.spec:
+            for dir in ['lib64', 'lib']:
+                libs = find_libraries('libEGL', join_path(self.prefix, dir),
+                                      shared=True, recursive=False)
+                if libs:
+                    result.extend(libs)
+                    break
+        return result
diff --git a/var/spack/repos/builtin/packages/paraview/package.py b/var/spack/repos/builtin/packages/paraview/package.py
index bb8b140b74..f5195dc2bb 100644
--- a/var/spack/repos/builtin/packages/paraview/package.py
+++ b/var/spack/repos/builtin/packages/paraview/package.py
@@ -49,6 +49,7 @@ class Paraview(CMakePackage, CudaPackage):
             description='Builds a shared version of the library')
     variant('kits', default=True,
             description='Use module kits')
+    variant('egl', default=False, description="Enable EGL")
 
     conflicts('+python', when='+python3')
     conflicts('+python', when='@5.6:')
@@ -58,6 +59,9 @@ class Paraview(CMakePackage, CudaPackage):
     # See commit: https://gitlab.kitware.com/paraview/paraview/-/commit/798d328c
     conflicts('~opengl2', when='@5.5:')
 
+    conflicts('+egl', when='+osmesa')
+    conflicts('+egl', when='+qt')
+
     # Workaround for
     # adding the following to your packages.yaml
     # packages:
@@ -89,6 +93,10 @@ class Paraview(CMakePackage, CudaPackage):
     depends_on('mesa+osmesa', when='+osmesa')
     depends_on('gl@3.2:', when='+opengl2')
     depends_on('gl@1.2:', when='~opengl2')
+
+    depends_on('glx', when='~osmesa platform=linux')
+    depends_on('egl', when='+egl')
+
     depends_on('libxt', when='~osmesa platform=linux')
     conflicts('+qt', when='+osmesa')
 
@@ -208,7 +216,9 @@ class Paraview(CMakePackage, CudaPackage):
         cmake_args = [
             '-DPARAVIEW_BUILD_QT_GUI:BOOL=%s' % variant_bool('+qt'),
             '-DVTK_OPENGL_HAS_OSMESA:BOOL=%s' % variant_bool('+osmesa'),
-            '-DVTK_USE_X:BOOL=%s' % nvariant_bool('+osmesa'),
+            '-DVTK_OPENGL_HAS_EGL:BOOL=%s' % variant_bool('+egl'),
+            ('-DVTK_USE_X:BOOL=%s' %
+                variant_bool('~osmesa ~egl platform=linux')),
             '-DVTK_RENDERING_BACKEND:STRING=%s' % rendering,
             '-DPARAVIEW_INSTALL_DEVELOPMENT_FILES:BOOL=%s' % includes,
             '-DBUILD_TESTING:BOOL=OFF',
@@ -272,7 +282,6 @@ class Paraview(CMakePackage, CudaPackage):
 
         if 'darwin' in spec.architecture:
             cmake_args.extend([
-                '-DVTK_USE_X:BOOL=OFF',
                 '-DPARAVIEW_DO_UNIX_STYLE_INSTALLS:BOOL=ON',
             ])