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

H. Peter Anvin
2013-06-20T22:36:06Z

On 06/20/2013 11:47 AM, Borislav Petkov wrote:
>
> I guess we can do a top-down allocation, starting from the highest
> virtual addresses:
>
> EFI_HIGHEST_ADDRESS
> |
> | size1
> |
> --> region1
> |
> | size2
> |
> --> region2
>
> ...
>
> and we make EFI_HIGHEST_ADDRESS be the same absolute number on every
> system.
>
> hpa, is this close to what you had in mind? It would be prudent to
> verify whether this will suit well with the kexec virtual space layout
> though...
>

This would work really well, I think. The tricky part here is to pick a
safe EFI_HIGHEST_ADDRESS as it is an ABI.

My preference would be to make EFI_HIGHEST_ADDRESS = -4 GB, which is
*not* what Windows uses, but will leave the high negative range clear,
and allows a range where we can grow down without much risk of
interfering with anything else.

-hpa