[Mesa-dev] [PATCH 1/4] egl: rework handling EGL_CONTEXT_FLAGS

[Boyan Ding]

2015-09-15 1:35 GMT+08:00 Emil Velikov <emil.l.velikov at gmail.com>:
> From: Matthew Waters <ystreet00 at gmail.com>
>
> As of version 15 of the EGL_KHR_create_context spec, debug contexts
> are allowed for ES contexts.  We should allow creation instead of
> erroring.
>
> While we're here provide a more comprehensive checking for the other two
> flags - ROBUST_ACCESS_BIT_KHR and FORWARD_COMPATIBLE_BIT_KHR
>
> v2 [Emil Velikov] Rebase. Minor tweak in commit message.
>
> Cc: Boyan Ding <boyan.j.ding at gmail.com>
> Cc: Chad Versace <chad.versace at intel.com>
> Cc: "10.6 11.0" <mesa-stable at lists.freedesktop.org>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91044
> Signed-off-by: Matthew Waters <ystreet00 at gmail.com>
> Signed-off-by: Emil Velikov <emil.l.velikov at gmail.com>
> ---
>  src/egl/main/eglcontext.c | 49 ++++++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 44 insertions(+), 5 deletions(-)
>
> diff --git a/src/egl/main/eglcontext.c b/src/egl/main/eglcontext.c
> index 588f489..ae19862 100644
> --- a/src/egl/main/eglcontext.c
> +++ b/src/egl/main/eglcontext.c
> @@ -152,12 +152,51 @@ _eglParseContextAttribList(_EGLContext *ctx, _EGLDisplay *dpy,
>
>           /* The EGL_KHR_create_context spec says:
>            *
> -          *     "Flags are only defined for OpenGL context creation, and
> -          *     specifying a flags value other than zero for other types of
> -          *     contexts, including OpenGL ES contexts, will generate an
> -          *     error."
> +          *     "If the EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR flag bit is set in
> +          *     EGL_CONTEXT_FLAGS_KHR, then a <debug context> will be created.
> +          *     [...]
> +          *     In some cases a debug context may be identical to a non-debug
> +          *     context. This bit is supported for OpenGL and OpenGL ES
> +          *     contexts."
> +          */
> +         if ((val & EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR) &&
> +             (api != EGL_OPENGL_API && api != EGL_OPENGL_ES_API)) {
> +            err = EGL_BAD_ATTRIBUTE;
> +            break;
> +         }
> +
> +         /* The EGL_KHR_create_context spec says:
> +          *
> +          *     "If the EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR flag bit
> +          *     is set in EGL_CONTEXT_FLAGS_KHR, then a <forward-compatible>
> +          *     context will be created. Forward-compatible contexts are
> +          *     defined only for OpenGL versions 3.0 and later. They must not
> +          *     support functionality marked as <deprecated> by that version of
> +          *     the API, while a non-forward-compatible context must support
> +          *     all functionality in that version, deprecated or not. This bit
> +          *     is supported for OpenGL contexts, and requesting a
> +          *     forward-compatible context for OpenGL versions less than 3.0
> +          *     will generate an error."
> +          */
> +         if ((val & EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR) &&
> +             (api != EGL_OPENGL_API || ctx->ClientMajorVersion < 3)) {
> +            err = EGL_BAD_ATTRIBUTE;
> +            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 (api != EGL_OPENGL_API && val != 0) {
> +         if ((val & EGL_CONTEXT_OPENGL_ROBUST_ACCESS_BIT_KHR) &&
> +             (api != EGL_OPENGL_API ||
> +              !dpy->Extensions.EXT_create_context_robustness)) {
>              err = EGL_BAD_ATTRIBUTE;
>              break;
>           }

I wonder if it's necessary to check the validity of the flags here,
since driCreateContextAttribs in src/mesa/drivers/dri/common/dri_util.c
also check those flags and the logic there seems to work.

Regards,
Boyan Ding

> --
> 2.5.0
>