Re: [tip:x86/microcode] x86/microcode_intel_early.c: Early updateucode on Intel's CPU

From: H. Peter Anvin
Date: Wed Dec 19 2012 - 21:38:14 EST

On 12/19/2012 04:29 PM, Jacob Shin wrote:
> On Wed, Dec 19, 2012 at 04:24:09PM -0800, H. Peter Anvin wrote:
>> On 12/19/2012 04:07 PM, Jacob Shin wrote:
>>> From what I remember, accessing memory around the memory hole (not
>>> just the HT hole, but e038000000 ~ 10000000000 on our mentioned system
>>> ) generated prefetches because the memory hole was marked as WB in PAT.
>>> I'll take a look at the system again, try the blanket MTRR covering
>>> 0xe000000000 ~ 1TB, and talk to our BIOS guys.
>> Yes, but do they all #MC (as opposed to, say, fetching all FFs)?
> Yes, MCE every time and it was fatal.

OK, one more question... there is something odd with the memory ranges here:

BIOS-e820: [mem 0x0000000100000000-0x000000e037ffffff] usable
BIOS-e820: [mem 0x000000e038000000-0x000000fcffffffff] reserved
BIOS-e820: [mem 0x0000010000000000-0x0000011ffeffffff] usable

The first usable range here is 4G to 896G + 896M which is an awfully
strange number. Similarly, the second range is 1T to 1T + 128G - 16M.
The little fiddly bits imply that there is either overshoot of some sort
going on -- possibly reserved memory -- or these are fairly arbitrary
sizes that don't match any physical bank sizes in which case it should
be possible to shuffle it differently...


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