Messages in this thread | | | From | Jesse Barnes <> | Subject | Re: [git head] Should X86_PAT really default to yes? | Date | Fri, 2 May 2008 13:40:24 -0700 |
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On Friday, May 02, 2008 12:37 pm Pallipadi, Venkatesh wrote: > >-----Original Message----- > >From: Frans Pop [mailto:elendil@planet.nl] > >Sent: Friday, May 02, 2008 12:22 PM > >To: linux-kernel@vger.kernel.org > >Cc: Pallipadi, Venkatesh; Ingo Molnar > >Subject: [git head] Should X86_PAT really default to yes? > > > >With X86_PAT enabled, when X is started I get about 40 lines > >(with varying > >addresses) like: > >kernel: Xorg:3358 /dev/mem expected mapping type write-back for > >807bf000-81000000, got uncached-minus
These messages? They're coming from the kernel it looks like, from the map_devmem routine in pat.c. I'm not sure they're accurate though; for PCI regions /dev/mem is *supposed* to map with UC- and not WB, so maybe this function needs to be updated?
> >And when X exits I get a bunch of lines like: > >kernel: Xorg:3349 freeing invalid memtype 80020000-8002a000 > > > >I also noticed artifacts (a band of about 2 cm high across the > >screen) after > >X goes to black but before the switch to VT1.
This is just a transient issue during VT switch or server exit though, right? X functionality isn't affected, and your VTs work fine? If so, it might not be a PAT issue but just a different memory layout or something (and therefore it would really just be a cosmetic bug in the X driver).
I really think PAT should be on by default; if you're running into real functional or performance problems we'd better get them fixed rather than disabling PAT...
Thanks, Jesse
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