[Mesa-dev] [PATCH 4/4] dri: Introduce SWAP_METHOD tokens

[Thomas Hellstrom]

On 08/10/2017 05:20 AM, Michel Dänzer wrote:
> On 09/08/17 06:53 PM, Thomas Hellstrom wrote:
>> We shouldn't be using GLX tokens in the dri subsystem, so define dri
>> SWAP_METHOD tokens and translate when necessary. Unfortunately the X server
>> uses the dri swap method value untranslated as the GLX fbconfig swapMethod,
>> so we can't enumerate these tokens arbitrarily, but rather need to make them
>> have the same values as the corresponding GLX tokens.
>>
>> Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
> [...]
>
>> diff --git a/src/gallium/state_trackers/dri/dri_screen.c b/src/gallium/state_trackers/dri/dri_screen.c
>> index 406e97d..1d9f441 100644
>> --- a/src/gallium/state_trackers/dri/dri_screen.c
>> +++ b/src/gallium/state_trackers/dri/dri_screen.c
>> @@ -156,7 +156,8 @@ dri_fill_in_modes(struct dri_screen *screen)
>>      boolean mixed_color_depth;
>>   
>>      static const GLenum back_buffer_modes[] = {
>> -      GLX_NONE, GLX_SWAP_UNDEFINED_OML, GLX_SWAP_COPY_OML
>> +      __DRI_ATTRIB_SWAP_NONE, __DRI_ATTRIB_SWAP_UNDEFINED,
>> +      __DRI_ATTRIB_SWAP_COPY
>>      };
> BTW, does this array need to include __DRI_ATTRIB_SWAP_EXCHANGE as well,
> or is it possible to use GLX_SWAP_EXCHANGE_OML anyway?
>
>
No it's not. I have a patch that adds __DRI_ATTRIB_SWAP_EXCHANGE for 
dri3 only (that's when the DRI driver / state tracker is initialized 
with the image loader extension) but still it doesn't get advertised 
since the advertised direct rendering fbconfigs are a subset only of the 
AIGLX exported fbconfigs, and AIGLX doesn't use the image loader 
extension / dri3 path. See the following email thread for more insight 
on this:

https://lists.freedesktop.org/archives/mesa-dev/2017-June/161417.html

As agreed in that thread, that should probably be remedied by rewriting 
the GLX fbconfig selection code so that the DRI startup decides what 
fbconfigs should be exported and the GLX code only makes sure there is a 
matching visual if needed. Since my primary motivation for doing these 
changes is to be able to run glretrace with GLX_SWAP_COPY_OML enabled, 
actually advertising GLX_SWAP_EXCHANGE_OML has lower priority ATM, but 
I'll try to do that at some point.

For the record, though, the code was tested with me unconditionally 
adding __DRI_ATTRIB_SWAP_EXCHANGE for both server and client and using a 
fixed version of  piglit glx-swap-exchange (posted on the piglit list).

Thanks,

Thomas