Messages in this thread | | | Date | Thu, 24 Jan 2008 16:27:58 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] x86: Construct 32 bit boot time page tables in native format. |
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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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