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

[Michael Tokarev <mjt@tls.msk.ru>]

20.05.2010 11:15, Andre Przywara wrote:
> Michael Tokarev wrote:
>> []
>>> 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)?

I replied in the original discussion -- after upgrading to SP6
there's no need in ,level=1 anymore, any -cpu variant works
without crashes.  The problem is to set it up, at least for
me, since I don't have sp6 integrated into setup.  Well, I
don't use winNT to start with, actually, so for me it's not
a problem at all ;) -- the reason why I asked is because I
have a debian bugreport about this very issue, see
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=575439
(and because I had winNT install handy)

But this is really interesting information - that winNT
fails on other CPUs too.  Thank you for that, now I can
close the debian bugreport ;)

>>>> 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.

Yeah, that's what i've seen too, it's exactly
ow it fails here with modern kvm.

> 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.


Thank you!

/mjt