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

Justin Piszcz
2007-06-01T17:57:39Z

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@nospamshaw.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