Re: 2.4.x ram issues?

From: Eugene Chupkin (ace@credit.com)
Date: Tue Feb 12 2002 - 21:52:59 EST


Here is the output of /proc/mtrr with the 4gb image

reg00: base=0xe0000000 (3584MB), size= 512MB: uncachable, count=1
reg01: base=0x00000000 ( 0MB), size=4096MB: write-back, count=1

And this is with 64gb image

reg00: base=0xe6000000 (3680MB), size= 32MB: uncachable, count=1
reg01: base=0xe8000000 (3712MB), size= 128MB: uncachable, count=1
reg02: base=0xf0000000 (3840MB), size= 256MB: uncachable, count=1
reg03: base=0x00000000 ( 0MB), size=8192MB: write-back, count=1
reg04: base=0x200000000 (8192MB), size=4096MB: write-back, count=1
reg05: base=0x300000000 (12288MB), size=2048MB: write-back, count=1
reg06: base=0x380000000 (14336MB), size=1024MB: write-back, count=1
reg07: base=0x3c0000000 (15360MB), size= 512MB: write-back, count=1

I'm not sure if that looks right, any ideas?

Thanks
-E

On Wed, 13 Feb 2002, Alan Cox wrote:

> > I have a problem with high ram support on 2.4.7 to 2.4.17 all behave the
> > same. I have a quad Xeon 700 box with 16gb of ram on an Intel SKA4 board.
> > The ram is all the same 16 1gb PC100 SDRAM modules from Crucial. If I
> > compile the kernel with high ram (64gb) support, my system runs very slow,
> > it takes about 15 minutes for make menuconfig to come up. If I recompile
> > the kernel with 4gb support, it runs perfectly normal and very fast, but I
> > have 12 gigs that I can't use. Is this a known issue? Is there a fix? I
> > tried just about everything and I am all out of options. Please help!
>
> Thats almost certainly indicating that the memory type range registers
> were not set up correcly by the BIOS. Check /proc/mtrr and also ask your
> vendor about BIOS updates to address the problem
>
> (If there aren't any you can hack around it but its not nice to let vendors
> get away with bugs if that indeed is what it is)
>

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