Re: [Bug 10843] Display artifacts on XOrg logout with PAT kernel and VESA framebuffer



On Sunday 15 June 2008, Siddha, Suresh B wrote:
Frans Pop wrote:
On Saturday 14 June 2008, Rafael J. Wysocki wrote:
Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=10843
Subject : Display artifacts on XOrg logout with PAT kernel
and VESA framebuffer
Submitter : Frans Pop <elendil@xxxxxxxxx>
Date : 2008-05-31 14:04 (15 days old)
References : http://lkml.org/lkml/2008/6/7/206

Yes. See also: http://lkml.org/lkml/2008/6/13/159

Frans, With or without pat, in the recent kernels (like 2.6.26-rc4/rc5
etc), ioremap() uses UC- and PCI mmap of /sys/devices/pci.../resource
(used by X) uses UC-

And fb_mmap() also uses UC-.

It's interesting that you don't see this artifact with "nopat".
Essentially with or with out pat enabled, we use the same memory
attributes. So depending on the MTRR setup (set by X server), effective
memory attribute across different mappings should be same (which is UC-
or WC with mtrr).

Any progress on this issue? It's still there with -rc7, but I doubt that
comes as a surprise.

Has anyone tried to reproduce this? I would think that should be trivial.

Just as a summary:
- Intel 82945G/GZ graphics [8086:2772] (ICH7 based system)
- FB_VESA=y, FRAMEBUFFER_CONSOLE=y
- boot with vga=791
- Log in to X and KDE; I do need to really log in there are no artifacts
if I exit X from the kdm login dialog
- artifacts show on logout

I doubt it's KDE related or even related to my specific graphics card.

It may well be related to what is or has been displayed on the display
before logging out, so running some apps may make sense. Seems like I do
see remnants of for example aptitude (Debian apt frontend) after I've run
it in an X term (KDE's konsole).

Cheers,
FJP
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Relevant Pages

  • Re: [Bug 10843] Display artifacts on XOrg logout with PAT kernel and VESA framebuffer
    ... Submitter: Frans Pop ... Frans, With or without pat, in the recent kernels (like 2.6.26-rc4/rc5 ... Log in to X and KDE; I do need to really log in there are no artifacts ... It may well be related to what is or has been displayed on the display ...
    (Linux-Kernel)
  • Re: [git head] Should X86_PAT really default to yes?
    ... The artifacts also appear when I log out from KDE (i.e. without exiting the ... server), and I also get the messages when logging out and logging in again. ... The artifacts may not be a PAT issue directly, but it is a clear regression ...
    (Linux-Kernel)
  • RE: [git head] Should X86_PAT really default to yes?
    ... Would you like me to file a bug against X for these artifacts? ... When I boot without 'vga=791', I hit another, unrelated ... that is the only other open issue related to PAT at this time. ...
    (Linux-Kernel)
  • Re: [git head] Should X86_PAT really default to yes?
    ... The artifacts also appear when I log out from KDE (i.e. ... I do not see any performance issues, but I've only used this kernel ... cosmetic bug in the X driver). ... I'm also 100% sure that it is caused by enabling PAT. ...
    (Linux-Kernel)
  • Re: [git head] Should X86_PAT really default to yes?
    ... I'm also 100% sure that it is caused by enabling PAT. ... with same config and only PAT disabled does not show the artifacts. ... Would you like me to file a bug against X for these artifacts? ... The i810 driver or the server? ...
    (Linux-Kernel)