Re: [PATCH -v2 0/4] EFI 1:1 mapping

Borislav Petkov
2013-06-19T16:59:12Z

On Wed, Jun 19, 2013 at 05:48:22PM +0100, Matthew Garrett wrote:
> > Ok, so it sounds like we want to *always* create both mappings but,
> > depending on what we want, to shove down SetVirtualAddressMap a
> > different set. And the 1:1 map will be the optional one which we give
> > SetVirtualAddressMap only when user wants it, i.e. when booting with
> > "efi=1:1_map".
>
> Yup, I think that sounds ideal.

Crap, I got completely sidetracked. The 1:1 mappings go in a different
pagetable (real_mode_header->trampoline_pgd) than the kernel one
(i.e. init_mm.pgd). However, the ->trampoline_pgd has all mappings
anyway, which means that if we want to do EFI runtime calls with the
high mappings but *also* have the 1:1 mappings established, we should
*always* switch to that pagetable when doing those calls.

hpa, MattF, agreed?

--
Regards/Gruss,
Boris.

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