[PATCH xserver 1/5] glamor: Handle GL_OUT_OF_MEMORY when allocating texture images.

[Pekka Paalanen]

On Wed, 18 Nov 2015 09:57:02 -0800
Eric Anholt <eric at anholt.net> wrote:

> Keith Packard <keithp at keithp.com> writes:
> 
> > Eric Anholt <eric at anholt.net> writes:
> >
> >> I think it's a safe enough assumption that we're not generating non-OOM
> >> errors.  And, now that we're logging errors, we should get reports of
> >> them sooner than we used to.
> >
> > Would it be sensible to wrap the glGetError call like this?
> >
> > GLenum
> > glamor_check_gl_oom() {
> >         GLenum last_oom = GL_NO_ERROR;
> >         GLenum error;
> >
> >         while ((error = glGetError()) != GL_NO_ERROR) {
> >                 if (error == GL_OUT_OF_MEMORY)
> >                         last_oom = error;
> >         }
> >         return last_oom;
> > }
> >
> > I admit I haven't looked at the Mesa glGetError() implementation, so I
> > don't know if there's a queue of errors, or just a bitfield.
> 
> "When an error is detected, a flag is set and the code is
> recorded. Further errors, if they occur, do not affect this recorded
> code. When GetError is called, the code is returned and the flag is
> cleared, so that a further error will again record its code."

GL ES 2.0 spec explicitly recommends to call it in a loop:
https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGetError.xml

and GL ES 3.2:
https://www.khronos.org/opengles/sdk/docs/man32/html/glGetError.xhtml

and OpenGL 4.5 also:
https://www.opengl.org/sdk/docs/man/html/glGetError.xhtml

My vague recollections are from OpenGL 2.1 era and already then you
called it in a loop until it cleared to be sure.


Thanks,
pq
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