[Mesa-dev] [PATCH mesa] dri: use a supported API in driCreateNewContext

[Eric Engestrom]

On Wednesday, 2018-02-14 09:06:41 -0500, Ilia Mirkin wrote:
> On Feb 14, 2018 7:38 AM, "Eric Engestrom" <eric.engestrom at imgtec.com> wrote:
> 
> From: Brendan King <Brendan.King at imgtec.com>
> 
> Don't assume the screen supports OpenGL when creating a new context,
> use an API that the screen supports.
> 
> Signed-off-by: Brendan King <Brendan.King at imgtec.com>
> Reviewed-by: Eric Engestrom <eric.engestrom at imgtec.com>
> [Eric: rebased on current git HEAD]
> Signed-off-by: Eric Engestrom <eric.engestrom at imgtec.com>
> ---
>  src/mesa/drivers/dri/common/dri_util.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/src/mesa/drivers/dri/common/dri_util.c
> b/src/mesa/drivers/dri/common/dri_util.c
> index e6a7d2391a78c45d45a1..3f32b34132e75228e0e0 100644
> --- a/src/mesa/drivers/dri/common/dri_util.c
> +++ b/src/mesa/drivers/dri/common/dri_util.c
> @@ -49,6 +49,7 @@
>  #include "main/debug_output.h"
>  #include "main/errors.h"
>  #include "main/macros.h"
> +#include "util/bitscan.h"
> 
>  const char __dri2ConfigOptions[] =
>     DRI_CONF_BEGIN
> @@ -325,7 +326,11 @@ driCreateContextAttribs(__DRIscreen *screen, int api,
>         mesa_api = API_OPENGLES;
>         break;
>      case __DRI_API_GLES2:
> +       ctx_config.major_version = 2;
> +       mesa_api = API_OPENGLES2;
> +       break;
>      case __DRI_API_GLES3:
> +       ctx_config.major_version = 3;
> 
> 
> Are you sure about this change? Doesn't seem related, and I'm about 20%
> sure there was some reason for the current thing.

I take the point that these are two separate bugs, and I'll split the
change and re-send, but I don't see the "reason for the current thing".
I'm betting on the 80% :P

Without this `major_version` being set, validate_context_version()
further down could accept a gles3 context when only gles2 is supported,
because `major_version` would be 1 for both and never `>2` or `>3`.

This is normally be hidden by the fact an attribute list with
__DRI_CTX_ATTRIB_MAJOR_VERSION would be passed, but
driCreateNewContextForAPI() doesn't pass an attribute list, which was in
turn hidden by driCreateNewContext() always requesting OPENGL, for which
1.0 is valid, if you support OpenGL (which a lot of dri drivers do, but
we don't anymore).

> 
>         mesa_api = API_OPENGLES2;
>         break;
>      case __DRI_API_OPENGL_CORE:
> @@ -514,7 +519,14 @@ static __DRIcontext *
>  driCreateNewContext(__DRIscreen *screen, const __DRIconfig *config,
>                      __DRIcontext *shared, void *data)
>  {
> -    return driCreateNewContextForAPI(screen, __DRI_API_OPENGL,
> +    int apifs;
> +
> +    apifs = ffs(screen->api_mask);
> +
> +    if (!apifs)
> +        return NULL;
> +
> +    return driCreateNewContextForAPI(screen, apifs - 1,
>                                       config, shared, data);
>  }
> 
> --
> Cheers,
>   Eric
>