[Mesa-dev] Early calls to st_validate_state

[Brian Paul]

If we really do need to call _mesa_update_state() for this, I think the 
right place would be in _mesa_blit_framebuffer(), not in the state tracker.

-Brian


On 06/26/2015 09:17 AM, Ilia Mirkin wrote:
> So that obviously avoids the crash. I guess I was unsure if that was
> the right way forward. The way that I understand it, there's "direct"
> state in the context, and there's derived state. And
> _mesa_update_state() will update the derived state. Since the various
> st atoms use derived state, doesn't it make sense to first just call
> _mesa_update_state?
>
> In nouveau, we also have a parameter which allows you to do partial
> state validations, i.e. a mask on the dirty flag to only flush certain
> things out. Not sure if that'd be helpful here.
>
>    -ilia
>
> On Fri, Jun 26, 2015 at 5:02 AM, Marek Olšák <maraeo at gmail.com> wrote:
>> I think the best way is not to do anything if one of the shaders is
>> NULL. Just like my patch that I just sent.
>>
>> Marek
>>
>> On Fri, Jun 26, 2015 at 3:04 AM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>>> Hello,
>>>
>>> A user reported a crash in wine in finalize_textures (called via
>>> st_validate_state). In this particular case it was happening through
>>> st_BlitFramebuffer (piglit test sent), but there are a number of
>>> callsites of st_validate_state from st/mesa.
>>>
>>> The reason it dies is that the fragment program isn't specified. Of
>>> course if that assumption were relaxed, it'd just crash later on in
>>> the process. Even though we specify _MaintainTexEnvProgram, that only
>>> gets bound somewhere down the line.
>>>
>>> One solution, which solved a number of different crashes for this user
>>> was to call _mesa_update_state(ctx) when making a context current for
>>> the first time. This normalizes a bunch of state, including setting
>>> the fragment/vertex programs which avoids the crash. Is this the right
>>> solution?
>>>
>>> Another thought I had was to call _mesa_update_state() from
>>> st_validate_state directly -- all the various state updates rely on
>>> mesa state being reasonable, and it seems to make sense to first flush
>>> those changes (which might e.g. update the currently-bound program, or
>>> all sorts of other things), and only then process the st's updates.
>>>
>>> However I'm unfamiliar with the reasoning behind the current system,
>>> so perhaps I'm also just missing something. Thoughts welcome.
>>>
>>>    -ilia