Re: [Qemu-devel] [PATCH 2/2] Route IOAPIC interrupts via ISA bus

[Jamie Lokier]

Gleb Natapov wrote:
> On Thu, Aug 27, 2009 at 09:40:06AM +0200, Gerd Hoffmann wrote:
> >            Or does it mean we must emulate a more recent chipset?
> > 
> That too will work.


Note that if you change the chipset, it'll break some existing Windows VMs.

I had this problem when porting a Windows Server 2003 VM from Virtual
PC to QEMU: Virtual PC emulates a PIIX4, while QEMU provides a PIIX3
(even though there's a PIIX4 in the source code, it's not used for PC
emulation).  The ported image would not boot because of the change of
chipset, until I patched the registry to accomodate the change.

It will be the same the other way: When some Windows VMs see a change
from PIIX3 to a later chipset, they will not boot.

Some Windows VMs don't care as much.  XP seems to be more like Linux,
in that it adapts to different devices at boot time.

-- Jamie




> 
> --
>                       Gleb.
> 
>