Bad caching of the scratch pixmap

Michel Dänzer michel at
Tue Apr 16 10:22:26 PDT 2013

On Die, 2013-04-16 at 10:54 -0600, Daniel Drake wrote: 
> On Sat, Apr 13, 2013 at 11:14 AM, Chris Wilson <chris at> wrote:
> > Given the same fix works, it does sound like a very similar issue. The
> > difference is that the DDX is under control of the creating the scratch
> > pixmap in your case and should be well aware of the lifetime constraints
> > and so remember to decouple the GPU object when it destroys the screen
> > pixmap. So the bug is really in the driver and this just happens to
> > workaround the bug by forcing the release
> Good that you have a feeling for where the real problem actually is.
> I'm happy to fix the driver, but I am facing a bit of a learning
> curve. If I get a good grasp on things, I will try to produce some
> documentation for the next person...
> So, the DDX is in control of pixmap allocations. It does that by
> providing these hooks:
>     if (pExa->flags & EXA_HANDLES_PIXMAPS)
>     {
>         pExa->CreatePixmap       = NULL;
>         pExa->CreatePixmap2      = mrvlExaCreatePixmap2;
>         pExa->DestroyPixmap      = mrvlDestroyPixmap;
>         pExa->ModifyPixmapHeader = mrvlModifyPixmapHeader;
>         pExa->PixmapIsOffscreen  = mrvlPixmapIsOffscreen;
>     }

Do you really need the ModifyPixmapHeader hook? It shouldn't be
necessary with CreatePixmap2. Do things work better without it? 

Earthling Michel Dänzer           |         
Libre software enthusiast         |          Debian, X and DRI developer

More information about the xorg-devel mailing list