Re: [Qemu-devel] [RFC] Bug Day - June 1st, 2010

[Andre Przywara]

Michael Tokarev wrote:
> 20.05.2010 02:30, Anthony Liguori wrote:
> > On 05/19/2010 05:29 PM, Andre Przywara wrote:
> > > Michael Tokarev wrote:
> > > > ...
> > > >
> > > > Also, thanks to Andre Przywara, whole winNT thing works but it requires
> > > > -cpu qemu64,level=1 (or level=2 or =3), -- _not_ with default CPU. This
> []
> > It'd be nice if we had more flexibility in defining custom machine types
> > so you could just do qemu -M win98.
>
> This is wrong IMHO.  win98 and winNT can run on various different
> machines, including all modern ones (yes I tried the same winNT
> on my Athlon X2-64, just had to switch SATA from AHCI to IDE;
> win95 works too)...  just not in kvm :)
Well, not really. You were lucky with your Athlon X2-64, actually it is 
the last machine not triggering the bug. I tried it on a AthlonII-X4 
(which has maxleaf=5 as any newer AMD machines) and it showed the same 
bug. On Intel boxes this bug should trigger on every CPU starting with 
some Pentium4 models, including all Core chips.
Have you tried versions with a newer service pack (SP6)?

> > > BTW: Does anyone knows what the problem with Windows95/98 on KVM is? I
> > > tried some tracing today, but couldn't find a hint.
>
> Um.  The bugreport(s) come as a surprize for me: I tried to
> install win98 in kvm several times in the past but setup
> always failed - different messages in different versions
> of kvm, either "unable to emulate" or "real mode trap" or
> something else, or just lockup, usually on first reboot.
> So - the bugreports talks about mouse non-working, but
> this means win98 itself works somehow...  I dunno :)
I think these bug reports are about plain QEMU. I tried it yesterday, in 
fact the mouse is non-functional. In KVM Windows95 gives me a black 
screen after the welcome screen with the moving bottom row. There are 
just two lines at the top: (translated from the german version)
While initializing device NTKERN:
Windows protection fault. Restart the computer.

KVM catched some #UDs due to ARPL from VM86 mode, but TCG got them too 
and it survived. So if anyone has some more hints, I'd be grateful.

Regards,
Andre.

--
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 448-3567-12