Re: [Qemu-devel] [PATCH v5 0/5] Support for S3 ACPI state (suspend to memory) in BIOS

[Carl-Daniel Hailfinger]

Hi,

On 27.11.2008 12:02, Gleb Natapov wrote:
> This patch series adds S3 (suspend to RAM) ACPI state to BIOS. Most
> changes concern themselves with preventing BIOS from using memory
> locations available to a guest OS.
>   

I see the problem you're facing with the overwrite and it looks there
might be a cleaner solution: If you can lock the CPU cache so that
writes don't get passed through to RAM, you're free to use any area
(with a few contraints) for stack without having to worry about
clobbering memory contents there.

That method is called Cache-as-RAM and I'm currently trying to implement
it in Qemu. I haven't looked into Bochs yet, but it should be doable
there as well.

coreboot (a free x86 firmware/BIOS replacement) is using Cache-as-RAM
and I believe quite a few commercial BIOSes use that technique as well.

Regards,
Carl-Daniel