[Qemu-devel] Re: [Bochs-developers] [PATCH v5 1/5] Add S3 state to DSDT. Handle resume event in the BIOS.

[Gleb Natapov]

On Sun, Dec 07, 2008 at 10:10:44AM -0500, Kevin O'Connor wrote:
> On Sun, Dec 07, 2008 at 11:20:31AM +0200, Gleb Natapov wrote:
> > On Sat, Dec 06, 2008 at 09:57:38PM -0500, Kevin O'Connor wrote:
> > > On Thu, Nov 27, 2008 at 01:02:25PM +0200, Gleb Natapov wrote:
> > > > +  ;; Save shutdown status
> > > > +  mov 0x04b0, bl
> > > > +
> > > > +  cmp bl, #0xfe
> > > > +  jz s3_post
> > > What sets 40:b0 to 0xfe on a resume?
> > Qemu/Bochs.
> 
> Thanks.
> 
> If we're going to set a flag to indicate a resume, I think we should
> use more than one byte to ensure we don't invoke that path on random
> memory.  (Maybe something like 0x5333524d -- 'S3RM'?)
> 
> Also, can the ACPI dsdt code set the flag instead of the emulators?
> 
Sorry I gave you a wrong answer. Qemu/BOCHS write 0xfe to CMOS offset
0xf (reboot reason) and BIOS saves it into 40:b0. We cannot write into
CMOS from AML since windows doesn't like it.

--

                        Gleb.