Re: [PATCH] x86: Construct 32 bit boot time page tables in native format.

Pavel Machek
2008-01-25T08:01:31Z

On Thu 2008-01-24 16:27:58, H. Peter Anvin wrote:
> Pavel Machek wrote:
> >>>
> >>I just looked at the ACPI suspend code, and it looks
> >>like it hacks its own identity map at runtime. Pavel,
> >>am I reading that code right?
> >
> >Yes, I think so, I believe we do it on both 32 and 64
> >bit now.
> >
>
> So the background to this... we need an identity map to
> trampoline at early boot, obviously, but we'd like it to
> not stick around more than necessary. We have
> zap_low_mappings() now but it's not really sufficient.
>
> Secondary SMP processors need these mappings during
> trampolining -- presumably including CPU hotplug -- and
> I'm suspecting it might simply make sense to use a
> separate set of page tables (with both the identity and
> the kernel map) for trampolining and just keep them
> around. That way they would be usable for ACPI as well.

That would enable some cleanups, yes.
Pavel
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