Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME regions

From: Ingo Molnar
Date: Sun Sep 27 2015 - 03:06:53 EST

* Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote:

> > If we allocate the EFI runtime as a single virtual memory block then issues
> > like rounding between sections does not even come up as a problem: we map the
> > original offsets and sizes byte by byte.
> Well, by that reasoning, we should not call SetVirtualAddressMap() in the first
> place, and just use the 1:1 mapping UEFI uses natively. This is more than
> feasible on arm64, and I actually fought hard against using
> SetVirtualAddressMap() at all, but I was overruled by others. I think this is
> also trivially possible on X64, since the 1:1 mapping is already active
> alongside the VA mapping.

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.


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