Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support

[BALATON Zoltan]

On Fri, 21 Jul 2017, Igor Mammedov wrote:
> On Fri, 21 Jul 2017 10:20:26 +0100
> "Daniel P. Berrange" <address@hidden> wrote:
> > On Thu, Jul 20, 2017 at 09:29:33PM +0200, Phil Dennis-Jordan wrote:
> > > On Thu, Jul 20, 2017 at 6:40 PM, Programmingkid
> > > <address@hidden> wrote:
> > > > I noticed that Windows 2000 does not boot up in QEMU recently. After bisecting 
> > > > the issue I found the offending commit:
> > >
> > > Ouch. I reckon we have 2 options for fixing this:
> > >
> > > 1. Export two FADTs, one ACPI 1.0, one ACPI 2.0. The latter would need
> > > to be pointed to by an XSDT, which Qemu currently doesn't implement at
> > > all as far as I'm aware. Any ideas on how SeaBIOS or OVMF would handle
> > > this? Any likely other OS regressions?
> > >
> > > 2. Select FADT version with an option. This one is definitely safe,
> > > but adds yet another option.
> > >
> > > Thoughts?
> >
> > The original comit below claims the change does not impact guest ABI
> > compatibility, so do we understand why Windows broke ?
> Author made a reasonable effort to test with variety of guest OSes upto
> vanilla WinXP, we can't blame ourselves for not testing OS that's is not
> available.
>
> Well we don't know why w2k breaks, only that it bisects to this commit.

I don't know if this helps but I've found that this same commit also broke 
booting OS X on q35 with OVMF and Clover (some old versions I had and 
worked before this commit). See here:
http://lists.nongnu.org/archive/html/qemu-devel/2017-06/msg04306.html

Maybe it's simpler to debug as these are open source but it's still not 
very clear why they fail because it starts to boot OS X but hangs during 
kernel init (and maybe Win2K fails to boot because of something else). I 
think I've seen this with OVMF 58f025afd and Clover 3354 (or around that, 
not completely sure about these versions).

Regards,
BALATON Zoltan