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

[H. Peter Anvin]

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.

> (It is early here. And I almost got the .c wakeup code to work... it
> already sets the mode).

Sweet!

	-hpa
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