Re: [PATCH 15/15] Revert "x86: default to reboot via ACPI"

Matthew Garrett
2008-11-09T10:24:23Z

On Sun, Nov 09, 2008 at 12:11:03PM +0200, Avi Kivity wrote:
> Matthew Garrett wrote:
> >Hmm. But we're seeing some machines that end up very confused if
> >rebooted via ACPI. I guess we need to run Vista on them to find out how
> >they behave. What OSI strings did your KVM setup expose? We know that
> >Windows changes behaviour under various circumstances depending on which
> >OS the firmware requests, so it's almost possible that this is another
> >of those cases.
> >
>
> Isn't it the other way around? The firmware changes behavior depending
> on how the OS identifies itself?

That also happens, yes.

> Reboot is a fixed feature IIRC, so it cannot change depending on
> identification strings.

The ID strings that the firmware requests give a good idea about which
operating systems the machine has been tested with. If Vista uses the
ACPI method then having the firmware request the OSI string for Vista
gives us a good indication that it's safe to use the ACPI method.

--
Matthew Garrett | mjg59@srcf.ucam.org