Re: [PATCH 1/2] x86-32: Fix crashes with CPU hotplug on AMD machines

From: H. Peter Anvin
Date: Thu Aug 05 2010 - 10:15:15 EST

On 08/05/2010 12:45 AM, Roedel, Joerg wrote:
> To make sure I understand correctly, you suggest to initialize
> tramponline_pg_dir in the boot sequence of the first cpu and fork
> swapper_pg_dir from it later on?


>> I realize this isn't how the 64-bit code works at the moment, but in a
>> lot of ways I think it would be better if it did.
> Yeah, may make sense. This patch already brings the 32 bit
> implementation closer to the 64 bit one. On 64 bit things are somewhat
> simpler because the tramponline page table can be defined at
> compile-time there (contains only 2 pgd_t entries) while on 32 bit we
> have to initialize it at runtime.

Correct, again. It's unclear to me if we can get away with the very
simple 64-bit approach -- in particular, not including all the 1:1
mappings in the kernel -- for all future users, though.


H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

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