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

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Message-ID: <CAE9FiQWDhPtTu_K_9rq1B2i2GByh7EMfbtpt+ZQBpRmo-fQo3A@mail.gmail.com>
Date:	Wed, 19 Dec 2012 15:45:20 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Jacob Shin <jacob.shin@....com>
Cc:	"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
	"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 Wed, Dec 19, 2012 at 3:40 PM, Jacob Shin <jacob.shin@....com> wrote:
> On Wed, Dec 19, 2012 at 03:22:13PM -0800, H. Peter Anvin wrote:
>> The other bit is that building the real kernel page tables iteratively
>> (ignoring the early page tables here) is safer, since the real page
>> table builder is fully aware of the memory map.  This means any
>> "spillover" from the early page tables gets minimized to regions where
>> there are data objects that have to be accessed early.  Since Yinghai
>> already had iterative page table building working, I don't see any
>> reason to not use that capability.
>
> Yes, I'll test again with latest, but Yinghai's patchset mapping only
> RAM from top down solved our problem.

that is for-x86-mm or tip:x86/mm2

we are taking about for-x86-boot, and it will allow kernel to be loaded above 4G
to solve the kdump problem.

so early map will have two way
1. extend head_64.S to cover kernel instead of just [0, 1G)
2. or peter's #PF handler version patch to set pg table dynamically.
    it could cover 1G when PF happens.

Yinghai
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