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

Ingo Molnar
2013-06-20T09:13:29Z

* Matthew Garrett <mjg59@srcf.ucam.org> wrote:

> On Wed, Jun 19, 2013 at 03:04:34PM +0200, Ingo Molnar wrote:
> > * Borislav Petkov <bp@alien8.de> wrote:
> > > And yet there are the Macs which reportedly cannot stomach this.
> >
> > Do we know why?
>
> I got lost in a maze of pointer arithmetic. There seems to be an
> assumption that nvram writes should be forbidden if in runtime mode but
> with pointers still below the phys/virt split, which obviously makes no
> sense but hey.
>
> But, as always, the only reliable thing to do here is to behave as much
> like Windows as possible. [...]

Amen ...

> [...] Which means performing the 1:1 mapping but maintaining the high
> mapping, and passing the high values via SetVirtualAddressMap.

Cool - and supposedly this will work in a Mac environment as well? Would
be very nice to avoid fundamentally fragile system specific quirks for
something as fundamental as the EFI runtime memory mapping model ...

Thanks,

Ingo