dell 2850 memory mapping

L.P.H. van Belle belle at
Fri Oct 19 06:28:35 CDT 2007

Hi, first try updating the bios.


>-----Oorspronkelijk bericht-----
>Van: linux-poweredge-bounces at 
>[mailto:linux-poweredge-bounces at] Namens michalwd1979
>Verzonden: vrijdag 19 oktober 2007 12:22
>Aan: linux-poweredge at
>Onderwerp: dell 2850 memory mapping
>I have found this old post on linux-pe list, originally 
>written by Roger White. These are exactly the same problems 
>that I have with my system now. I tried some tricks with 
>/proc/mtrr, but I can not set any write-combining region. Does 
>anyone know any fix to this? It seems that mtrrs are messed up 
>but do You all have the same problems? Or is this only my 
>problem with specific linux distro or something?
>Please help, Michael.
>2850, BIOS A02, 4GB memory.
>There is something weird going on with the BIOS memory mapping.
>Linux 64GB SMP kernel (Distro is irrelevant, 2.6 kernel) - 
>From boot.msg :
><4> BIOS-e820: 0000000000000000 - 00000000000a0000 (usable)
><4> BIOS-e820: 0000000000100000 - 00000000cffc0000 (usable)
><4> BIOS-e820: 00000000cffc0000 - 00000000cffcfc00 (ACPI data)
><4> BIOS-e820: 00000000cffcfc00 - 00000000cffff000 (reserved)
><4> BIOS-e820: 00000000e0000000 - 00000000fec90000 (reserved)
><4> BIOS-e820: 00000000fed00000 - 00000000fed00400 (reserved)
><4> BIOS-e820: 00000000fee00000 - 00000000fee10000 (reserved)
><4> BIOS-e820: 00000000ffb00000 - 0000000100000000 (reserved)
><4> BIOS-e820: 0000000100000000 - 0000000130000000 (usable)
> From /proc/mtrr :
>reg00: base=0x00000000 (   0MB), size=4096MB: write-back, count=1
>reg01: base=0x100000000 (4096MB), size= 512MB: write-back, count=1
>reg02: base=0x120000000 (4608MB), size= 256MB: write-back, count=1
>reg03: base=0xd0000000 (3328MB), size= 256MB: uncachable, count=1
>reg04: base=0xe0000000 (3584MB), size= 512MB: uncachable, count=1
>Errr, three-quarter gig normal memory space as uncachable ?
>The onboard VGA in the 2850 is a stripped ATI Radeon with 16MB VRAM.
>However, lspci -v (snip) :
>0000:09:0d.0 VGA compatible controller: ATI Technologies Inc 
>Radeon RV100 
>QY [Radeon 7000/VE] (prog-if 00 [VGA])
>         Subsystem: Dell: Unknown device 016d
>         Flags: bus master, VGA palette snoop, stepping, 
>medium devsel, 
>latency 32, IRQ 7
>         Memory at d0000000 (32-bit, prefetchable) [size=128M]
>         I/O ports at bc00 [size=256]
>         Memory at df3f0000 (32-bit, non-prefetchable) [size=64K]
>         Expansion ROM at df300000 [disabled] [size=128K]
>         Capabilities: [50] Power Management version 2
>Xorg correctly determines it has only 16MB but fails to get the 
>write-combining area :
>kernel: mtrr: type mismatch for d0000000,1000000 old: write-back new: 
>Any thoughts/comments ?
>Roger While
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