linux-kernel - Re: Case: 7454422: Re: Kernel 2.6.21.3 does not work with 8GB of RAM on Intel 965WH motherboards. (FULL DMESG)

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Date:	Fri, 1 Jun 2007 13:57:31 -0400 (EDT)
From:	Justin Piszcz <jpiszcz@...idpixels.com>
To:	Robert Hancock <hancockr@...w.ca>
cc:	Parag Warudkar <parag.warudkar@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: Case: 7454422: Re: Kernel 2.6.21.3 does not work with 8GB of
 RAM on Intel 965WH motherboards. (FULL DMESG)



On Fri, 1 Jun 2007, Justin Piszcz wrote:

>
>
> On Wed, 30 May 2007, Robert Hancock wrote:
>
>> Parag Warudkar wrote:
>>> Robert Hancock wrote:
>>> 
>>> 
>>>> 0-3319MB
>>>> 4096-8832MB
>>>> 
>>>> leaving 64MB of memory at the top of RAM uncached. What do you want to
>>>> bet that something important (kernel code?) is getting loaded there..
>>>> 
>>>> So essentially it's a BIOS problem, it's not setting up the MTRRs
>>>> properly in order to map all of RAM as cacheable. As Andi says, complain
>>>> to Intel.
>>>> 
>>> 
>>> Could the BADRAM patch be useful for him?
>>> http://rick.vanrein.org/linux/badram/download.html has 2.6.21 version.
>>> It says it supports x86_64. May be using this patch he can exclude
>>> that RAM from being used/accessed?
>> 
>> I think that mem=8832M would work as well, to make the kernel use only the 
>> memory that is marked cacheable. (It looks like this parameter takes the 
>> highest memory address we want the kernel to use, not the highest memory 
>> amount.)
>> 
>> -- 
>> Robert Hancock      Saskatoon, SK, Canada
>> To email, remove "nospam" from hancockr@...pamshaw.ca
>> Home Page: http://www.roberthancock.com/
>> 
>
> Is 8832MB a typo?  8GB of memory is ~8192MB right?  Did you mean 8132MB or? 
> Intel wants me to flash my bios and reset everything to the defaults to see 
> if it is still an issue, I'd prefer to try the mem= option first.
>
> Justin.
>

mem=8064M" [top: Mem:   7264144k total]
mem=8832M" [top: Mem:   8039820k total]

I am using 8832MB and it does not have the bug/slowness!  How did you 
calculate that from the MTRR output?

$ cat /proc/mtrr
reg00: base=0x00000000 (   0MB), size=2048MB: write-back, count=1
reg01: base=0x80000000 (2048MB), size=1024MB: write-back, count=1
reg02: base=0xc0000000 (3072MB), size= 256MB: write-back, count=1
reg03: base=0xcf800000 (3320MB), size=   8MB: uncachable, count=1
reg04: base=0xcf700000 (3319MB), size=   1MB: uncachable, count=1
reg05: base=0x100000000 (4096MB), size=4096MB: write-back, count=1
reg06: base=0x200000000 (8192MB), size= 512MB: write-back, count=1
reg07: base=0x220000000 (8704MB), size= 128MB: write-back, count=1

It sees 7.66GB now!

8039820 / 1024 / 1024
7.66GB

top - 13:56:48 up 3 min,  5 users,  load average: 0.12, 0.14, 0.06
Tasks: 163 total,   1 running, 162 sleeping,   0 stopped,   0 zombie
Cpu0  :  4.4%us,  1.4%sy,  0.2%ni, 89.7%id,  4.1%wa,  0.0%hi,  0.1%si,  0.0%st
Cpu1  :  0.1%us,  0.5%sy,  0.6%ni, 98.4%id,  0.3%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu2  :  1.2%us,  0.3%sy,  0.1%ni, 97.9%id,  0.5%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu3  :  0.2%us,  1.9%sy,  0.7%ni, 96.0%id,  1.1%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   8039820k total,  1039588k used,  7000232k free,     3552k buffers
Swap: 16787768k total,        0k used, 16787768k free,   141480k cached



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