[Mesa-dev] [PATCH] st/mesa: conditionally enable GL_NV_vdpau_interop

[Christian König]

Am 22.01.2016 um 19:24 schrieb Ilia Mirkin:
> On Fri, Jan 22, 2016 at 1:15 PM, Christian König
> <deathsimple at vodafone.de> wrote:
>>> Form autofoo perspective things look great.
>> Thanks, that exactly what I wanted to know.
>>
>>> Although I second Ilia's concern - we need a form of runtime detection
>>> here. Pretty much all distros ship the vdpau(+ other video driver
>>> backend) in a separate library. Thus this will likely get us nowhere
>>> we want - as I'm suspecting this is to assist the unsuspecting user,
>>> which hasn't installed package X or Y in the first place ?
>> As I said, Mesa should NOT check what vdpau backend libraries are installed
>> or used before advertising NV_vdpau_interop.
>>
>> Take a look at how the interop works, NV_vdpau_interop should be advertised
>> if the OpenGL implementation provides the necessary functions. What and if a
>> VDPAU backend gets loaded to work with that is completely independent of
>> this.
>>
>> We want to switch over to a DMABuf based interop implementation so that we
>> can get away from using the Mesa internal structures.
>>
>> This not only has the advantage of fixing this ugly hack, but also would
>> allow an application to decode on one driver (radeonsi) and display with
>> another one (r600).
> If the purpose is not to conditionally not advertise based on
> availability, what is the purpose of this patch?

To check if we compile the state tracker as well and so fulfill the 
dependencies of the state tracker.

E.g. for example for a DMABuf based interop I might need some defines 
from the VDPAU headers.

The alternative is to make the OpenGL implementation depend on the 
presence of libvdpau directly, but I had the feeling that this approach 
would be more convenient.

Sorry for the confusion, I never intended to make any this an extra 
check for the unsuspecting user. But rather just solve the dependencies 
without checking for libvdpau twice.

I should have probably better explained that in the first place.

Regards,
Christian.

>
>    -ilia