[PATCH xserver 07/13] glx: Use __glXInitExtensionEnableBits in all backends

[Jon Turney]

On 30/03/2016 12:48, Emil Velikov wrote:
> On 23 March 2016 at 22:46, Adam Jackson wrote:
>> On xquartz this enables SGI_make_current_read, which is a mostly
>> harmless lie as CGL doesn't implement it, as well as SGIX_pbuffer, which
>> is fine because no pbuffer-enabled configs are created.
>>
>> On xwin this enables SGIX_pbuffer and ARB_multisample in all cases.
>> Again this is harmless if the backend doesn't support the features,
>> since no fbconfigs will be created to expose them.
>>
>> It also adds SGIX_visual_select_group to both xquartz and xwin.
>> Amusingly, both were filling in the appropriate field in the fbconfig
>> already.
[...]
> Similar to patch 5 - we assume that things will be fine if the base
> implementation lacks the WGL extensions. As this can cause the
> occasional wtf moment - wouldn't it be better to have a big fat
> warning for each of these (three so far) missing extensions alongside
> the proposed behaviour ?
>
> Jon, any ideas how (un)common it is for WGL_ARB_make_current_read,
> WGL_ARB_pbuffer and/or WGL_ARB_multisample to be missing ?

Very unlikely, I think.

The only common case would be where the VGA driver is in use and the 
'GDI generic' software renderer is offered, which is explicitly 
blacklisted anyhow, (so glxWinScreenProbe() fails and we fall back to 
swrast)

I guess some logging here that these expected extensions aren't present 
might be useful.