linux-kernel - Re: [tip:x86/microcode] x86/microcode_intel_early.c: Early update ucode on Intel's CPU

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Date:	Wed, 19 Dec 2012 18:37:45 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jacob Shin <jacob.shin@....com>
CC:	Borislav Petkov <bp@...en8.de>, Yinghai Lu <yinghai@...nel.org>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	"mingo@...nel.org" <mingo@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"linux-tip-commits@...r.kernel.org" 
	<linux-tip-commits@...r.kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Stefano Stabellini <Stefano.Stabellini@...citrix.com>
Subject: Re: [tip:x86/microcode] x86/microcode_intel_early.c: Early update
 ucode on Intel's CPU

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...

	-hpa

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