[Mesa-dev] [RFC PATCH shader-db 2/2] run: request a debug context

[Ilia Mirkin]

On Mon, Nov 9, 2015 at 1:56 PM, Matt Turner <mattst88 at gmail.com> wrote:
> On Mon, Nov 9, 2015 at 10:46 AM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>> On Mon, Nov 9, 2015 at 1:35 PM, Matt Turner <mattst88 at gmail.com> wrote:
>>> On Sun, Nov 8, 2015 at 8:53 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>>>> st/mesa only prints messages in a debug context. Without always enabling
>>>> the message generation, I don't see a way to hook into the glEnable() to
>>>> turn it on/off.
>>>> ---
>>>>  run.c | 1 +
>>>>  1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/run.c b/run.c
>>>> index 73e468d..1d8d3b1 100644
>>>> --- a/run.c
>>>> +++ b/run.c
>>>> @@ -417,6 +417,7 @@ main(int argc, char **argv)
>>>>          EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR,
>>>>          EGL_CONTEXT_MAJOR_VERSION_KHR, 3,
>>>>          EGL_CONTEXT_MINOR_VERSION_KHR, 2,
>>>> +        EGL_CONTEXT_FLAGS_KHR, EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR,
>>>>          EGL_NONE
>>>>      };
>>>>      EGLContext core_ctx = eglCreateContext(egl_dpy, cfg, EGL_NO_CONTEXT,
>>>
>>> Is this a limitation of st/mesa, or am I using the KHR_debug API
>>> incorrectly? It's my understanding that you can get KHR_debug messages
>>> without a debug context by calling glEnable(GL_DEBUG_OUTPUT), and it
>>> looks like this is supported by the KHR_debug spec.
>>
>> But I don't want to be generating the debug info in my driver for no
>> reason. For example I have a timing-type debug message which gets the
>> current time (to report how long a sync fence wait takes). This is a
>> non-free operation that I want to avoid if no one's looking.
>
> Huh, looks like we do quite a bit of work before we throw the message
> away. We could probably make that process a lot simpler.
>
>> I can see this both ways... perhaps the more expensive messages should
>> be keyed on whether it's a debug context and the compiler message
>> should always be reported. Or perhaps we can just create a debug
>> context here and be done with it.
>
> I guess you can determine that based on
> DEBUG_SEVERITY_{HIGH,MEDIUM,LOW,NOTIFICATION}?

There's no driver notification about that (that I'm aware). Should there be?

I don't really see how that can work, since I think you're supposed to
be able to have multiple ones in a group. But I'm new to that API...
if there's a driver hook that I missed or variable I should be looking
at, please educate :)

  -ilia