[Mesa-dev] [RFC] egl: stop claiming support for pbuffer + msaa (RFC)

[Emil Velikov]

On 27 September 2016 at 13:47, Marek Olšák <maraeo at gmail.com> wrote:
> On Tue, Sep 27, 2016 at 2:34 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>> On 26 September 2016 at 08:41, Tapani Pälli <tapani.palli at intel.com> wrote:
>>> This fixes a crash in egl-create-msaa-pbuffer-surface Piglit test
>>> and same crash in many dEQP EGL tests.
>>>
>>> I also found that some Qt example did a workaround because of this
>>> crash: https://bugreports.qt.io/browse/QTBUG-47509
>>>
>>> Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
>>> ---
>>>
>>> This is RFC as I'm not sure if we are supposed to support this. I tried
>>> to verify overall pbuffer situation with some mesa-demos using pbuffer
>>> but those are not working for me at all with or without my patch.
>>>
>>>  src/egl/main/eglconfig.c | 5 +++++
>>>  1 file changed, 5 insertions(+)
>>>
>>> diff --git a/src/egl/main/eglconfig.c b/src/egl/main/eglconfig.c
>>> index 6161d26..20cf9d4 100644
>>> --- a/src/egl/main/eglconfig.c
>>> +++ b/src/egl/main/eglconfig.c
>>> @@ -407,6 +407,11 @@ _eglValidateConfig(const _EGLConfig *conf, EGLBoolean for_matching)
>>>        return EGL_FALSE;
>>>     }
>>>
>>> +   /* pbuffer with MSAA not supported */
>> Fwiw on my system piglit also crashes + the demos don't render
>> anything. So I'm leaning that we want this as-is (for the time being)
>> + cc stable ?
>>
>> Can you apply a minor polish to the comment - "XXX/TODO: pbuffer +
>> MSAA does not work + QT bugreport" or alike.
>
> Please don't add "XXX/TODO". pbuffers were spec'd in 1997 and were
> meant to be used on GL 1.x hardware that didn't support MSAA
> texturing, thus MSAA pbuffers don't make any sense. Just keep the
> current comment.
>
Can we use your reply instead - it's wise to have the not as often
visited parts nicely documented ?

pbuffers + msaa seems to be working fine on GLX so it shouldn't be too
crazy to add support for EGL. Then again, until/if that happens all we
need is to clear the EGL_PBUFFER_BIT if we have a MSAA config in
dri2_add_config(). Props to Ian for the reminder that SurfaceType is a
bitmask :-)

Thanks
Emil