Messages in this thread | | | Date | Sat, 30 Jul 2005 09:40:06 +0800 | Subject | Re: vesafb-fix-mtrr-bugs.patch added to -mm tree | From | "Antonino A. Daplas" <> |
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Andrew Morton wrote: > Dave Jones <davej@redhat.com> wrote: >> On Fri, Jul 29, 2005 at 11:24:37AM -0700, Andrew Morton wrote: >> >> > From: "Antonino A. Daplas" <adaplas@gmail.com> >> > >> > >> vesafb: mode is 800x600x16, linelength=1600, pages=16 >> > >> vesafb: scrolling: redraw >> > >> vesafb: Truecolor: size=0:5:6:5, shift=0:11:5:0 >> > >> mtrr: type mismatch for fc000000,1000000 old: write-back new: write- >> > >> combining >> > >> > Range is already set to write-back, vesafb attempts to add a write-combining >> > mtrr (default for vesafb). >> > >> > >> mtrr: size and base must be multiples of 4 kiB >> > >> > This is a bug, vesafb attempts to add a size < PAGE_SIZE triggering >> > the messages below. >> >> I fixed this a few weeks back. It's this line which your patch removes.. >> >> - while (temp_size > PAGE_SIZE && >> >> > To eliminate the warning messages, you can add the option mtrr:2 to add a >> > write-back mtrr for vesafb. Or just use nomtrr option. >> >> If we need users to pass extra command line args to make warnings go >> away, we may as well not bother. Because 99% of users will be completely >> unaware that option even exists. They'll still see the same message, >> and still report the same bugs. >> >> The pains of MTRR strike again. This stuff is just screaming for >> a usable PAT implementation. Andi, you were working on that, any news ? >> Or should I resurrect Terrence's patch again ? >> > > Well something is still awry: > > > > > Begin forwarded message: > > Date: Fri, 29 Jul 2005 13:40:05 +0200 > From: Alessandro <alezzandro@gmail.com> > To: Andrew Morton <akpm@osdl.org> > Subject: Re: "mtrr: type mismatch for e0000000,8000000 old: write-back new: write-combining" on Kernel 2.6.12 > > > I try the new prepatch for the stable Linux kernel (2.6.13-rc4) but > the problem is the same: > ... > vesafb: framebuffer at 0xe0000000, mapped to 0xe0880000, using 4608k, > total 131072k > vesafb: mode is 1024x768x24, linelength=3072, pages=55 > vesafb: protected mode interface info at c000:56cb > vesafb: scrolling: redraw > vesafb: Truecolor: size=0:8:8:8, shift=0:16:8:0 > mtrr: type mismatch for e0000000,8000000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,4000000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,2000000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,1000000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,800000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,400000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,200000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,100000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,80000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,40000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,20000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,10000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,8000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,4000 old: write-back new: write-combining > mtrr: type mismatch for e0000000,2000 old: write-back new: write-combining
Vesafb defaults to write-combining mtrr. But the memory range is already set to write-back so mtrr_check() spewed the above messages. I don't think it has any ill effects, but if you want to eliminate the above messages, tell vesafb to also use write-back mtrr by adding the boot option "mtrr:2" (or nomtrr).
I think I'll submit a documentation patch.
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