Re: [PATCH v2] hw/i386: place setup_data at fixed place in memory

[Jason A. Donenfeld]

On Thu, Aug 4, 2022 at 2:11 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> Hi Laszlo,
>
> On Thu, Aug 04, 2022 at 01:31:36PM +0200, Laszlo Ersek wrote:
> > None of the existing info passing methods seem early enough, generic
> > enough, and secure enough (at the same time)...
>
> Can you look at the v2 patch? It seems to work on every configuration I
> throw at it. Keep in mind that setup_data is only used very, very early.
> I can think of a few other places to put it too, looking at the x86
> memory map, that will survive long enough.
>
> I think this might actually be a straightforwardly solvable problem if
> you think about it more basically.

And just to put things in perspective here... We only need like 48
bytes or something at some easy fixed address. That's not much. That's
*got* to be a fairly tractable problem. If v2 has issues, I can't see
why there wouldn't be a different easy place to put a meger 48 bytes
of stuff that then is allowed to be wiped out after early boot.

Jason