Arch Linux

el mariachi

Member

Registered: 2007-11-30

Posts: 595

[drm] MTRR allocation failed. > Say what?

Fresh install of Arch on my Dell E5400 with GM45 graphics (glxinfo says command not found :s so I can't output a full info)

the message pops up in messages.log during boot

 agpgart-intel 0000:00:00.0: Intel GM45 Chipset
 agpgart-intel 0000:00:00.0: detected 32764K stolen memory
 agpgart-intel 0000:00:00.0: AGP aperture is 256M @ 0xe0000000
..
 [drm] Initialized drm 1.1.0 20060810
 i915 0000:00:02.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16
 mtrr: type mismatch for e0000000,10000000 old: write-back new: write-combining
 [drm] MTRR allocation failed.  Graphics performance may suffer.
 [drm] set up 31M of stolen space 

I can't find any flaw in my system graphics-wise (other than the usual tearing in h.264 movies)
But if fixing this means squeezing more performance, I want to fix it
Any idea what this is about?

Gusar

Member

Registered: 2009-08-25

Posts: 3,605

Re: [drm] MTRR allocation failed. > Say what?

The intel driver uses PAT for some time now instead of MTRR. So even if you could fix your MTRR, you wouldn't see any difference. If you want a quick test, start your machine with nopat on the kernel commandline in grub. Now graphics performance will suffer.

el mariachi

Member

Registered: 2007-11-30

Posts: 595

Re: [drm] MTRR allocation failed. > Say what?

so it's just a misleading message? cool thanks for the heads-up