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

Justin Piszcz
2007-05-31T18:44:20Z

On Thu, 31 May 2007, Robert Hancock wrote:

> Justin Piszcz wrote:
>> On Thu, 31 May 2007, Parag Warudkar wrote:
>>
>>> Robert Hancock wrote:
>>>> 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.)
>>>>
>>> Yep, and that would be much easier too.
>>>
>>> I am curious though as this seems to be somewhat common a problem, could
>>> we make the kernel analyze which memory is not cacheable (it already knows
>>> this via MTRR) and not use that portion for anything? Plus may be warn the
>>> user to contact their BIOS vendor to correct the problem?
>>>
>>> I think that would be possible - even if the kernel knows late that the
>>> memory was uncached we could migrate those pages in that region to
>>> someplace else?
>>>
>>> Parag
>>>
>>
>> That is an excellent question and I wonder the same thing. I also had this
>> problem when I only used 4GB of ram and upgraded the (another motherboard,
>> I have two) past version 1666P and I had no idea what was going on other
>> than the BIOS did not work correctly.
>>
>> In this case however it worked with 4GB with bios version 1612P but not
>> with 8GB. Is this the case of a buggy BIOS for the 965 chipset or do Intel
>> boards have a lot of issues?
>
> We could conceivably generate a warning if the MTRRs don't map all of the
> physical memory as write-back. Actually, conceivably we could actually go and
> fix up the MTRRs if we found them to be wrong according to the E820 memory
> map. That would be more complicated, however.
>
> --
> Robert Hancock Saskatoon, SK, Canada
> To email, remove "nospam" from hancockr@nospamshaw.ca
> Home Page: http://www.roberthancock.com/
>

Intel is working on a work-around/fix for this problem, they said I need
to wait another day or so until it is completed. I will let everyone know
what the outcome is, hopefully it is a good fix :) I totally agree
however, a lot of 'weird' problems that some people may attribute to Linux
are actually BIOS problems, I think warnings in the kernel would be a good
idea, then they would not have to blame the kernel for BIOS issues :)

Justin.