[waffle] [PATCH 1/3] glx: don't use ARB_create_context with pre 3.0 contexts

[Chad Versace]

On 04/06/2016 02:12 AM, Jose Fonseca wrote:
> On 05/04/16 22:45, Emil Velikov wrote:
>> This way if the user requests GL pre 3.0 context which lacks the
>> flags/extra bits which require ARB_create_context one can safely fall
>> back to the normal/legacy entry point.
>>
>> This resolves piglits on non 3.0 capable drivers such as classic swrast,
>> nouveau_vieux and alike.
>>
>> Cc: Jose Fonseca <jfonseca at vmware.com>
>> Cc: Ilia Mirkin <imirkin at alum.mit.edu>
>> Signed-off-by: Emil Velikov <emil.l.velikov at gmail.com>



>> +static inline bool
>> +glx_context_needs_arb_create_context(const struct wcore_config_attrs *attrs)
>> +{
>> +    if (attrs->context_api == WAFFLE_CONTEXT_OPENGL &&
>> +        (wcore_config_attrs_version_ge(attrs, 30) ||
>> +         attrs->context_forward_compatible))
>> +        return true;
>> +
>> +    if (attrs->context_debug)
>> +        return true;
>> +
>> +    return false;
>> +}

> Looks good to me.  Thanks.
> 
> Reviewed-by: Jose Fonseca <jfonseca at vmware.com>

I reviewed the thread on the Piglit list, and I'm in favor of this change.

Jose and Emil, I believe the critical version should be 3.2, not 3.0. I don't
understand why this patch uses 3.0 as the cutoff version.  The
GLX_ARB_create_context spec says:

    The presence of an OpenGL 3.2 or later implementation determines whether or
    not GLX_ARB_create_context_profile is required.

And the WGL spec contains the same text.

In other words, it never makes sense to request a 3.2 context without
GLX_ARB_create_context, because the availability of 3.2 mandates the
availability of GLX_ARB_create_context_profile.