Re: [patch 02/11] PAT x86: Map only usable memory in x86_64 identity map and kernel text

From: Andi Kleen
Date: Thu Jan 10 2008 - 14:07:15 EST


venkatesh.pallipadi@xxxxxxxxx writes:

> x86_64: Map only usable memory in identity map.

I don't think that is needed or makes sense for reserved/ACPI * etc.
Only e820 holes should be truly unmapped because only those should
contain mmio.

> All reserved memory maps to a
> zero page.

Why zero page? Why not unmap.

Anyways you could make that a zillion times more simple by just rounding
the e820 areas to 2MB -- for the holes only that should be ok I think;
i would expect them to be near always already suitably aligned.

In short this can be all done much simpler.

-Andi
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