[Intel-gfx] [PATCH xf96-video-intel] DRI2GetMSC: Do not send a bogus ust when no drawable is not displayed

[Stéphane Marchesin]

On Fri, Mar 29, 2013 at 2:07 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> On Fri, Mar 29, 2013 at 01:54:37PM +0800, Daniel Kurtz wrote:
>> According to the opengl glx_sync_control spec, the Unadjusted System Time
>> (or UST) is a 64-bit monotonically increasing counter that is available
>> throughout the system:
>> http://www.opengl.org/registry/specs/OML/glx_sync_control.txt
>>
>> Therefore, sending 0, even in this corner case, is out of spec.
>> Instead, just return FALSE indicating that the operation could not be
>> completed.
>
> The problem is that ends up sending BadDrawable back to the client,
> which ends up killing many clients and a compositor or two due to the
> unexpected error.
>
> Would you prefer querying pipe 0 in this case for the UST?

For us it comes down to the fact that we'd like something monotonous.
So yes querying pipe 0 could work if it's enabled. But I wonder what
do you do when you have no enabled pipe though? Return the last UST?

Stéphane