* Borislav Petkov <[email protected]> wrote:
> On Sun, Sep 27, 2015 at 09:06:44AM +0200, Ingo Molnar wrote:
>
> > Could we please re-list all the arguments pro and contra of 1:1 physical
> > mappings, in a post that also explains the background so that more people
> > can
> > chime in, not just people versed in EFI internals? It's very much possible
> > that a bad decision was made.
>
> The main reason why we did the additional, top-down mapping was kexec kernel
> wanting to use UEFI runtime facilities too and the braindead design of
> SetVirtualAddressMap() being callable only once per system boot. So we had to
> have stable mappings which are valid in the kexec-ed kernel too.
>
> But this was long time ago and I most certainly have forgotten all the
> details.
>
> And now I'm wondering why didn't we do the 1:1 thing and rebuild the exact
> same
> EFI pagetable in the kexec-ed kernel? Because when we do an EFI call, we
> switch
> to the special pagetable so why didn't we make the kexec-ed kernel rebuild
> the
> 1:1 pagetable which it can use for EFI calls...
Yeah.
> Hmm, again, I've forgotten a lot of details so I'm sure Matt will come in and
> say "No, you can't do that because..."
Would be nice to re-examine all this.
Thanks,
Ingo
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