[Openchrome-users] [openChrome] #332: Very slow 2D experience with VX800 on NC20

[OpenChrome Trac]

#332: Very slow 2D experience with VX800 on NC20
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 Reporter:  freeseek     |        Owner:  somebody
     Type:  enhancement  |       Status:  new     
 Priority:  minor        |    Component:  exa     
  Version:  trunk        |   Resolution:          
 Keywords:               |     Blocking:          
Blockedby:               |  
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Comment(by bigboss):

 I do have a NC20 up and running fine with Ubuntu 9.10. So I think I can
 help you:

 There are 2 problems:
  1. Missing MTRR entries, workaround: ENABLE X86_PAT (new kernel)
  2. CPU frequency fixed on 800MHz due to bug with acpi-cpufreq (patch is
 being reviewed at VIA)

 To 1:
 There is a problem with current X.org and a problematic function in the
 Linux kernel that leads to the fact that no write-combining MTRR entries
 are created for the framebuffer memory. A patch fixing this will maybe be
 included in 2.6.33 (yes, quite sure not even 2.6.32). The patch can be
 found here:
 [http://git.kernel.org/?p=linux/kernel/git/next/linux-
 next.git;a=commitdiff;h=2992e545ea006992ec9dc91c4fa996ce1e15f921]

 The workaround is to enable X86_PAT in the kernel configuration. This is
 done in nearly every distribution, Ubuntu also does this since kernel
 version 2.6.31-13.45:
 [http://kernel.ubuntu.com/git?p=ubuntu/ubuntu-
 karmic.git;a=commitdiff;h=a611fa50121f1698bd367b991f66e2268eb10824]

 So, the solution for you is simple: Upgrade your kernel!

 To 2:
 Now, as the acpi-cpufreq kernel module is used for frequency scaling on
 VIA Nano there is a bug preventing the processor to spped up to its full
 performance. Instead it seems to stay at 800MHz. I am in contact with VIA
 about this, and a patch fixing it should be released soon.

 Until then you may modify your kernel config and disable acpi-cpufreq.

 I hope this helps.
 Kind regards,
   Thomas

-- 
Ticket URL: <http://www.openchrome.org/trac/ticket/332#comment:10>
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