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 | |
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
|  |