Re: Qemu / KVM On Powermac G5 MP970

[Daniel Henrique Barboza]

Ccing Mark

On 1/12/23 11:18, Dan Whitehouse wrote:
> Hi all,
> I have a Powermac G5 running Debian (from Ports) with kernel version:
>
> Linux powermac-g5 6.0.0-6-powerpc64 #1 SMP Debian 6.0.12-1 (2022-12-09) ppc64 
> GNU/Linux
>
> My aim is to get Qemu working with KVM acceleration, although I am unsure if 
> that is even possible.
> Any attempt to do so seems to result in the behaviour described here:
>
> Re: [PATCH 2/9] target/ppc: add errp to kvmppc_read_int_cpu_dt() 
> <https://www.mail-archive.com/qemu-devel@nongnu.org/msg898334.html>
> mail-archive.com 
> <https://www.mail-archive.com/qemu-devel@nongnu.org/msg898334.html>
>         apple-touch-icon-114x114.png 
> <https://www.mail-archive.com/qemu-devel@nongnu.org/msg898334.html>
>
> <https://www.mail-archive.com/qemu-devel@nongnu.org/msg898334.html>
>
> I have managed (after a fair bit of struggle to get Debian working under qemu 
> (without kvm) and I also got MacOS 9 working as well (albeit with horribly 
> garbled colours).
>
> Ive seen some posts on the KVM mailing list that may refer to whatever is going 
> wrong here:
>
> 'Re: [PATCH] kvm-pr: manage illegal instructions' 
> <https://marc.info/?l=kvm-ppc&m=146364192030854&w=2>
> marc.info <https://marc.info/?l=kvm-ppc&m=146364192030854&w=2>
>         <https://marc.info/?l=kvm-ppc&m=146364192030854&w=2>
>
> <https://marc.info/?l=kvm-ppc&m=146364192030854&w=2>
>
>
> And it may well be the case that this is a KVM issue more than a Qemu wrong and 
> I’m therefore posting in the wrong list (in which case apologies). As you can 
> see though there has been no activity since 2016.

I took a look at the thread and I'm not entirely convinced that QEMU is 100%
in the clear. The root issue seems to be kvm-pr kernel code though.

Mark managed to run kvm-pr in a G5 in the past so I believe he can help you
with any pointers. What I can say that you'll have a bumpy road ahead - kvm-pr
is being maintained mostly via code-wide changes in kvm that needs to touch
kvm-pr code to remove some deprecated API and etc. Eventually someone will face
a kvm-pr exclusive problem and try to land a fix (as you saw in that 2016 
thread).


> I’d be grateful if either someone could confirm that this is a non starter or 
> give me any pointers.

It's not a non-starter - it's feasible and it was done before. But I'd say 
you're
in for some heavy kernel (and probably QEMU) hacking to make it work properly.


Thanks,

Daniel

> Thanks,
>
> Dan