Re: [Qemu-devel] POLL: Why do you use kqemu?

[Jamie Lokier <jamie@shareable.org>]

Avi Kivity wrote:
> Jamie Lokier wrote:
> >Johannes Schindelin wrote:
> >  
> >>>Yeah I don't either.  I actually thought kvm had replaced it effectively.
> >>>      
> >>You might have realized from the available answers that not everybody is 
> >>lucky enough to be able to afford 2 week old hardware, and therefore not 
> >>everybody is able to use kvm.
> >>    
> >
> >Plus kvm's not suitable for some guests.  I'm thinking old Windows
> >guests with 16-bit kernel code here.
> >  
> 
> kvm on amd will run these perfectly.

So the "Guest Support Status" prominently on the front page of
linux-kvm.org is wrong for current versions?  It specifically mentions
AMD hosts.

(I notice AMD KVM != Intel KVM hasn't factored into this discussion yet...)

Guest           KVM tested             Host CPU/bits    Result
----------------------------------------------------------------
Windows 98SE 	kvm-63                 Intel 32         Fails
Windows 98SE 	kvm-80, 2.6.27.7       AMD 64           no way
Windows 95 	kvm-44, 2.6.23-rc8     AMD 64, 32 	no way

> >It has come up before that kvm will eventually support 16-bit code
> >better, although I got the impression that it would never support full
> >16-bit virtualisation accurately, so e.g. Windows 95 will not run on
> >it, nor some other partially 16-bit OSes.  Possibly not even very old
> >versions of Linux, I'm not sure.
> >
> >Don't ask me _why_ I want to run them. :-)
> >
> >Just a data point that it's not just about the host hardware, and as
> >far as I know kqemu can accelerate them.
> >  
> 
> It falls back to qemu for 16-bit code.

I was under the impression it was planned to remove TCG support when
using KVM.  If not, fine, it's ok for 16-bit code to run in TCG and
probably better than vm86 or the in-kernel interpreter.

-- Jamie