Re: fb layer & ioremap_wc

[Frans Pop <elendil@planet.nl>]

FYI

This is from a thread started on lkml about a regression with 2.6.26-rc1 
where artifacts are shown when X is exited if X86_PAT is enabled. 

The full thread can be seen here:
http://www.gossamer-threads.com/lists/linux/kernel/914812?do=post_view_threaded

The most relevant part starts here:
http://www.gossamer-threads.com/lists/linux/kernel/915956?do=post_view_threaded

On Monday 05 May 2008, Jesse Barnes wrote:
> On Monday, May 05, 2008 11:59 am Frans Pop wrote:
> > On Monday 05 May 2008, you wrote:
> > > On Monday, May 05, 2008 10:32 am Frans Pop wrote:
> > > > I suspect it could be vesafb/fbcon related instead. Normally I boot
> > > > my system with 'quiet vga=791', i.e. with vesafb. I then see the
> > > > artifacts.
> > > >
> > > > When I boot with 'video=vfb:off', I do _not_ get the artifacts when
> > > > X exits.
> > >
> > > Ahhh, I missed that part of your config.  That could definitely have
> > > an effect on things...  You'll probably want something like the
> > > attached
> >
> > Not sure what to make of this.
> > With your patch I still get the artifacts, but they are displayed a lot
> > shorter. I get only a flash instead of a-2 seconds.
>
> Hm, so I guess some other user is still using UC on the region.  [Note to
> fb list:  the patch just made vesafb use ioremap_wc instead of ioremap).
>
> > > (there are other places in the fb layer that want similar treatment,
> > > iirc, maybe fb_pgprotect?).
> >
> > Do you want to try a more complete review/patch or should this be
> > punted over to the framebuffer folks?
>
> Yeah, those bits have changed since I last looked at them, hopefully the
> fb guys can help.


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