[Mesa-dev] [PATCH] egl: Emit correct error when robust context creation fails

[Chad Versace]

Fixes dEQP-EGL.functional.create_context_ext.robust_*
on Intel with GBM.

If the user sets the EGL_CONTEXT_OPENGL_ROBUST_ACCESS_BIT_KHR in
EGL_CONTEXT_FLAGS_KHR when creating an OpenGL ES context, then
EGL_KHR_create_context spec requires that we unconditionally emit
EGL_BAD_ATTRIBUTE because that flag does not exist for OpenGL ES. When
creating an OpenGL context, the spec requires that we emit EGL_BAD_MATCH
if we can't support the request; that error is generated in the egl_dri2
layer where the driver capability is actually checked.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99188
Cc: mesa-stable at lists.freedesktop.org
---
 src/egl/main/eglcontext.c | 38 ++++++++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 12 deletions(-)

diff --git a/src/egl/main/eglcontext.c b/src/egl/main/eglcontext.c
index 60625f6470..5313e1dabc 100644
--- a/src/egl/main/eglcontext.c
+++ b/src/egl/main/eglcontext.c
@@ -184,19 +184,33 @@ _eglParseContextAttribList(_EGLContext *ctx, _EGLDisplay *dpy,
             break;
          }
 
-         /* The EGL_KHR_create_context_spec says:
-          *
-          *     "If the EGL_CONTEXT_OPENGL_ROBUST_ACCESS_BIT_KHR bit is set in
-          *     EGL_CONTEXT_FLAGS_KHR, then a context supporting <robust buffer
-          *     access> will be created. Robust buffer access is defined in the
-          *     GL_ARB_robustness extension specification, and the resulting
-          *     context must also support either the GL_ARB_robustness
-          *     extension, or a version of OpenGL incorporating equivalent
-          *     functionality. This bit is supported for OpenGL contexts.
-          */
          if ((val & EGL_CONTEXT_OPENGL_ROBUST_ACCESS_BIT_KHR) &&
-             (api != EGL_OPENGL_API ||
-              !dpy->Extensions.EXT_create_context_robustness)) {
+             api != EGL_OPENGL_API) {
+            /* The EGL_KHR_create_context spec says:
+             *
+             *   10) Which error should be generated if robust buffer access
+             *       or reset notifications are requested under OpenGL ES?
+             *
+             *       As per Issue 6, this extension does not support creating
+             *       robust contexts for OpenGL ES. This is only supported via
+             *       the EGL_EXT_create_context_robustness extension.
+             *
+             *       Attempting to use this extension to create robust OpenGL
+             *       ES context will generate an EGL_BAD_ATTRIBUTE error. This
+             *       specific error is generated because this extension does
+             *       not define the EGL_CONTEXT_OPENGL_ROBUST_ACCESS_BIT_KHR
+             *       and EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY_KHR
+             *       bits for OpenGL ES contexts. Thus, use of these bits fall
+             *       under condition described by: "If an attribute is
+             *       specified that is not meaningful for the client API
+             *       type.." in the above specification.
+             *
+             * The spec requires that we emit the error even if the display
+             * supports EGL_EXT_create_context_robustness. To create a robust
+             * GLES context, the *attribute*
+             * EGL_CONTEXT_OPENGL_ROBUST_ACCESS_EXT must be used, not the
+             * *flag* EGL_CONTEXT_OPENGL_ROBUST_ACCESS_BIT_KHR.
+             */
             err = EGL_BAD_ATTRIBUTE;
             break;
          }
-- 
2.11.0