linux-kernel - Re: 2.6.27 mtrr fixes do not work when X starts

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Date:	Fri, 22 Aug 2008 12:11:07 +0200
From:	Helge Hafting <helge.hafting@...el.hist.no>
To:	Yinghai Lu <yhlu.kernel@...il.com>
CC:	Alexander Huemer <alexander.huemer@....ac.at>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: 2.6.27 mtrr fixes do not work when X starts

I also see mtrr problems. I use 2.6.27-rc4, with this in my .config:
CONFIG_MTRR=y
CONFIG_MTRR_SANITIZER=y
CONFIG_MTRR_SANITIZER_ENABLE_DEFAULT=1
CONFIG_MTRR_SANITIZER_SPARE_REG_NR_DEFAULT=1
(Have no idea what the last one is about, the docs didn't say.)

Everything is fine during boot, I see this in dmesg:
Found optimal setting for mtrr clean up
gran_size: 1M   chunk_size: 64M         num_reg: 7      lose RAM: 0M
range0: 0000000000000000 - 000000007c000000
Setting variable MTRR 0, base: 0MB, range: 1024MB, type WB
Setting variable MTRR 1, base: 1024MB, range: 512MB, type WB
Setting variable MTRR 2, base: 1536MB, range: 256MB, type WB
Setting variable MTRR 3, base: 1792MB, range: 128MB, type WB
Setting variable MTRR 4, base: 1920MB, range: 64MB, type WB
range: 000000007c000000 - 0000000080000000
Setting variable MTRR 5, base: 1984MB, range: 64MB, type WB
hole: 000000007ff00000 - 0000000080000000
Setting variable MTRR 6, base: 2047MB, range: 1MB, type UC
x86 PAT enabled: cpu 0, old 0x7040600070406, new 0x7010600070106
After WB checking
MTRR MAP PFN: 0000000000000000 - 0000000000080000
After UC checking
MTRR MAP PFN: 0000000000000000 - 000000000007ff00
After sorting
MTRR MAP PFN: 0000000000000000 - 000000000007ff00

X gets problems however, from my Xorg.0.log:(II) VESA(0): initializing int10
(II) VESA(0): Primary V_BIOS segment is: 0xc000
(II) VESA(0): VESA BIOS detected
(II) VESA(0): VESA VBE Version 3.0
(II) VESA(0): VESA VBE Total Mem: 14336 kB
(II) VESA(0): VESA VBE OEM: NVIDIA
(II) VESA(0): VESA VBE OEM Software Rev: 96.134
(II) VESA(0): VESA VBE OEM Vendor: NVIDIA Corporation
(II) VESA(0): VESA VBE OEM Product: G86 Board - dawson0
(II) VESA(0): VESA VBE OEM Product Rev: Chip Rev
(II) VESA(0): Splitting WC range: base: 0xfb000000, size: 0xe00000
(II) VESA(0): Splitting WC range: base: 0xfb800000, size: 0x600000
(==) VESA(0): Write-combining range (0xfbc00000,0x200000)
(WW) VESA(0): Failed to set up write-combining range (0xfb800000,0x600000)
(WW) VESA(0): Failed to set up write-combining range (0xfb000000,0xe00000)
(II) VESA(0): virtual address = 0x7f17bd6dd000,
         physical address = 0xfb000000, size = 14680064

And dmesg says:
mtrr: no more MTRRs available
mtrr: no more MTRRs available

So I get one write-combining range where X wants three.
$ cat /proc/mtrr
reg00: base=0x00000000 (   0MB), size=1024MB: write-back, count=1
reg01: base=0x40000000 (1024MB), size= 512MB: write-back, count=1
reg02: base=0x60000000 (1536MB), size= 256MB: write-back, count=1
reg03: base=0x70000000 (1792MB), size= 128MB: write-back, count=1
reg04: base=0x78000000 (1920MB), size=  64MB: write-back, count=1
reg05: base=0x7c000000 (1984MB), size=  64MB: write-back, count=1
reg06: base=0x7ff00000 (2047MB), size=   1MB: uncachable, count=1
reg07: base=0xfbc00000 (4028MB), size=   2MB: write-combining, count=1

2MB does obviously not cover the entire framebuffer. :-(

Helge Hafting
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