[Mesa-dev] [PATCH 00/15] Make ARB_direct_state_access exclusive to core profile

[Ian Romanick]

On 05/18/2015 06:36 PM, Dave Airlie wrote:
> On 19 May 2015 at 11:02, Ian Romanick <idr at freedesktop.org> wrote:
>> On 05/18/2015 05:35 PM, Ian Romanick wrote:
>>> On 05/18/2015 02:34 PM, Dave Airlie wrote:
>>>> On 19 May 2015 at 07:28, Ian Romanick <idr at freedesktop.org> wrote:
>>>>> With the patches already on the piglit list, the only change is
>>>>> gettextureimage-formats, gettextureimage-formats init-by-rendering, and
>>>>> gettextureimage-luminance change from pass to skip.
>>>>
>>>> This might be a naive question, with dummy false core only,
>>>>
>>>> how do we ensure these APIs are never called in non-core scenarios?
>>>>
>>>> does the dispatch layer handle that for us?
>>>
>>> Yes, but I need to add another patch to make that happen.  Thanks for
>>> reminding me. :)  That will end up being patch 14.5 / 15.
>>
>> Ugh.  It turns out that Ilia is correct.  We can control just about
>> everything else, but we can't make functions core profile-only.  And
>> this is already a bug for functions added by:
>>
>>     ARB_draw_indirect
>>     ARB_multi_draw_indirect
>>     ARB_gpu_shader_fp64
>>     ARB_texture_buffer_object
>>     ARB_texture_buffer_range
>>     ARB_vertex_attrib_64bit
>>     ARB_viewport_array
>>
>> These extensions are all marked "GLC" in extensions.c.  The functions
>> check the extension bits, but they don't check the API... and drivers
>> set the bit without regard for the API.
>>
>> GOOD TIMES WERE HAD BY ALL.
> 
> I got bad feelings when I was doing ARB_shader_subroutine, and removing
> all the if enabled bits if it was going to be core only, glad I held off!

The enable bits don't help.

If you make a compatibility-profile context, right now
GL_ARB_draw_indirect is not in the extensions string.  However, if you
call glDrawIndirect, something (other than just setting
GL_INVALID_OPERATION) will happen.  _mesa_DrawIndirect will check the
extension bit, see that the driver set it, and merrily go about its
business.

Either way, I think I've figured out how I want this implemented, and I
should have patches out in a few hours.

> Dave.