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

From: Yinghai Lu
Date: Wed Dec 19 2012 - 18:45:13 EST

On Wed, Dec 19, 2012 at 3:40 PM, Jacob Shin <jacob.shin@xxxxxxx> 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.

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