[PATCH] exa: fix gnome-panel corruption

Michel Dänzer michel at daenzer.net
Mon Feb 15 07:30:20 PST 2010

On Thu, 2010-02-11 at 20:06 +0100, Maarten Maathuis wrote: 
> 2010/2/11 Michel Dänzer <michel at daenzer.net>:
> >
> > Thanks for tackling this, Maarten!
> >
> > On Thu, 2010-02-11 at 19:05 +0100, Maarten Maathuis wrote:
> >> - A mapped pixmap can't be used for acceleration, any decent memory manager
> >> will refuse this.
> >> - Source pixmaps may need updating, so move in the pixmap unconditionally, it
> >> should be a no-op in most cases anyway.
> >
> > 'May need'? Have you actually observed this in practice? Only the mixed
> > pixmap pointed to by pExaScr->deferred_mixed_pixmap should ever have
> > valid bits in the system memory copy with no corresponding valid bits in
> > the GPU copy. In which case the new code could still be conditionalized
> > on
> Yes i have observed this in practice, the reason is "fairly" obvious.
> Do software rendering on full pixmap, do hardware rendering as src
> with preg (driver pixmap created), do software rendering (sw pixmap is
> killed, but not everything is in hardware pixmap yet).


> One possibility would be to put "exaDoMigration" with src with preg on
> the deferred pixmap list, i haven't tested this, but i could try this
> evening or tomorrow.

Thanks for the clarification and for the extra effort to show another
possible approach. I agree the first approach is cleaner.

> > It should be possible to restructure the code such that the late_failure
> > label and goto aren't necessary.
> You cannot assume the prepare access to succeed the 2nd time, although
> it will in 99.99% of the time.

No such assumption is necessary:

      * Call ExaDoPrepareAccess(). 
      * On success, do the new thing, call ExaDoPrepareAccess() again. 
      * Take the current failure path if either ExaDoPrepareAccess()
        call failed.

> > Is there a bug report that can be referenced in the commit message?
> Not to my knowledge.

http://bugs.freedesktop.org/show_bug.cgi?id=26076 ?

Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer

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