[Mesa-dev] [RFC 1/3] dri: add support for CONTEXT_FLAG_NO_ERROR_BIT_KHR

[Nicolai Hähnle]

On 28.03.2017 06:35, Timothy Arceri wrote:
> The KHR_no_error spec says:
>
>    "CONTEXT_FLAG_NO_ERROR_BIT_KHR is only supported if the
>    OpenGL version has support for context flags (as defined
>    in the OpenGL 4.5 core spec) or an  extension supporting
>    equivalent functionality is exposed."
>
> But the OpenGL 4.5 core spec just has referenced to
> {WGL,GLX}_ARB_create_context. There is also no
> GLX_create_context_no_error so I'm unsure if the text from
> the spec implies that it extends {WGL,GLX}_ARB_create_context
> or if a new extension is actually required.

WGL/GLX extensions for this are in progress and should be released 
reasonably soon.

Cheers,
Nicolai

> ---
>  include/GL/internal/dri_interface.h    |  2 ++
>  src/mesa/drivers/dri/common/dri_util.c | 16 +++++++++++++++-
>  2 files changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/include/GL/internal/dri_interface.h b/include/GL/internal/dri_interface.h
> index 86efd1b..44840a9 100644
> --- a/include/GL/internal/dri_interface.h
> +++ b/include/GL/internal/dri_interface.h
> @@ -1041,20 +1041,22 @@ struct __DRIdri2LoaderExtensionRec {
>  #define __DRI_CTX_ATTRIB_RESET_STRATEGY		3
>
>  #define __DRI_CTX_FLAG_DEBUG			0x00000001
>  #define __DRI_CTX_FLAG_FORWARD_COMPATIBLE	0x00000002
>
>  /**
>   * \requires __DRI2_ROBUSTNESS.
>   */
>  #define __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS	0x00000004
>
> +#define __DRI_CTX_FLAG_NO_ERROR			0x00000008
> +
>  /**
>   * \name Context reset strategies.
>   */
>  /*@{*/
>  #define __DRI_CTX_RESET_NO_NOTIFICATION		0
>  #define __DRI_CTX_RESET_LOSE_CONTEXT		1
>  /*@}*/
>
>  /**
>   * \name Reasons that __DRIdri2Extension::createContextAttribs might fail
> diff --git a/src/mesa/drivers/dri/common/dri_util.c b/src/mesa/drivers/dri/common/dri_util.c
> index f6df488..6d7f1df 100644
> --- a/src/mesa/drivers/dri/common/dri_util.c
> +++ b/src/mesa/drivers/dri/common/dri_util.c
> @@ -418,21 +418,22 @@ driCreateContextAttribs(__DRIscreen *screen, int api,
>       * requested API to API_OPENGL_CORE.
>       *
>       * In Mesa, a debug context is the same as a regular context.
>       */
>      if ((flags & __DRI_CTX_FLAG_FORWARD_COMPATIBLE) != 0) {
>         mesa_api = API_OPENGL_CORE;
>      }
>
>      const uint32_t allowed_flags = (__DRI_CTX_FLAG_DEBUG
>                                      | __DRI_CTX_FLAG_FORWARD_COMPATIBLE
> -                                    | __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS);
> +                                    | __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS
> +                                    | __DRI_CTX_FLAG_NO_ERROR);
>      if (flags & ~allowed_flags) {
>  	*error = __DRI_CTX_ERROR_UNKNOWN_FLAG;
>  	return NULL;
>      }
>
>      if (!validate_context_version(screen, mesa_api,
>                                    major_version, minor_version, error))
>         return NULL;
>
>      context = calloc(1, sizeof *context);
> @@ -459,20 +460,33 @@ driCreateContextAttribs(__DRIscreen *screen, int api,
>  }
>
>  void
>  driContextSetFlags(struct gl_context *ctx, uint32_t flags)
>  {
>      if ((flags & __DRI_CTX_FLAG_FORWARD_COMPATIBLE) != 0)
>          ctx->Const.ContextFlags |= GL_CONTEXT_FLAG_FORWARD_COMPATIBLE_BIT;
>      if ((flags & __DRI_CTX_FLAG_DEBUG) != 0) {
>         _mesa_set_debug_state_int(ctx, GL_DEBUG_OUTPUT, GL_TRUE);
>          ctx->Const.ContextFlags |= GL_CONTEXT_FLAG_DEBUG_BIT;
> +    } else if ((flags & __DRI_CTX_FLAG_NO_ERROR) != 0) {
> +        /* From Issue (1) of the KHR_no_error spec:
> +         *
> +         *    "How does this extension interact with KHR_robustness and debug
> +         *    contexts?
> +         *
> +         *    RESOLVED: The EGL/WGL/GLX layers should prevent these features
> +         *    from being enabled at the same time.  However, if they are
> +         *    somehow enabled at the same time this extension should be
> +         *    ignored."
> +         */
> +        if ((flags & __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS) == 0)
> +           ctx->Const.ContextFlags |= GL_CONTEXT_FLAG_NO_ERROR_BIT_KHR;
>      }
>  }
>
>  static __DRIcontext *
>  driCreateNewContextForAPI(__DRIscreen *screen, int api,
>                            const __DRIconfig *config,
>                            __DRIcontext *shared, void *data)
>  {
>      unsigned error;
>
>


-- 
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.