> On 9/16/07, Howard Chu <hyc@symas.com> wrote:
>> Yinghai Lu wrote:
>> > On 9/14/07, Howard Chu <hyc@symas.com> wrote:
>> >> Hi, was wondering if anyone else has been tripped up by this... I've got
> 4GB of
>> >> RAM in my Asus A8V Deluxe and memory hole mapping enabled in the BIOS. By
>> >> default, my system boots up with these MTRR settings:
>> >>
>> >> reg00: base=0x00000000 ( 0MB), size=4096MB: write-back, count=1
>> >> reg01: base=0x100000000 (4096MB), size=1024MB: write-back, count=1
>> >> reg02: base=0xc0000000 (3072MB), size=1024MB: uncachable, count=1
>> >> reg03: base=0xc0000000 (3072MB), size= 256MB: write-combining, count=1
>
> if rev F before cpu aka Rev E is installed, and 8G RAM installed, it will be
>> >> reg00: base=0x00000000 ( 0MB), size=8192MB: write-back, count=1
>> >> reg01: base=0x100000000 (8192MB), size=1024MB: write-back, count=1
>> >> reg02: base=0xc0000000 (3072MB), size=1024MB: uncachable, count=1
>> >> reg03: base=0xc0000000 (3072MB), size= 256MB: write-combining, count=1
> and you will have problem...
>
> So good way is get the ram top, and hole size...and reset the whole
> set ot var mtrr.
>
> you could refer the code in LinuxBIOS about setting that...
>
http://www.openbios.org/viewvc/trunk/LinuxBIOSv2/src/cpu/x86/mtrr/mtrr.c?revision=2616...
> esp the part about CONFIG_VAR_MTRR_HOLE...
>
> but Andi and Eric said resetting mtrr is not good... when someone from
> intel try to trim the MTRR for intel CPU.
