Re: Qemu / KVM On Powermac G5 MP970

[BALATON Zoltan]

Hello,

On Tue, 24 Jan 2023, Dan Whitehouse wrote:
> Luigi,
> Thanks for getting back to me.
> I just tried:
>
> qemu-system-ppc \
>  -L pc-bios \
>  -boot c \
>  -M mac99,via=pmu \
>  -enable-kvm \
>  -cpu g4 \
>  -m 2048 \
>  -prom-env 'auto-boot?=true' \
>  -prom-env 'boot-args=-v' \
>  -prom-env 'vga-ndrv?=true' \
>  -drive file=/srv/Qemu/debian_32bit.qcow2,format=qcow2,media=disk \
>  -netdev user,id=mynet0,net=192.168.76.0/24,dhcpstart=192.168.76.10 \
>  -device sungem,netdev=mynet0 \
>  -monitor stdio

Unrelated to the issue but this could be simplified.

- vga-ndrv?=true is the default so you don't need that

- same for auto-boot? (you only need that if you want to set it to false to 
stop before booting)

- -boot-args=-v only works for Mac OS X, not useful for other OSes

- -cpu g4 is only needed for qemu-system-ppc64 (this is a confuding option 
discussed in another thread)

- -boot c is the default too so usually only -boot d is needed if you want to 
change it to boot from CD.

- The whole -netdev user -device sungem is probably not needed as -net 
user is the default and mac99 has a sungem device by default so unless the 
10.0.0.0 network this uses would not work for you, you probably don't need 
these. This user network is separate internal network, not the same as 
your other networks so the IP range is only a problem if your local 
network also uses the same which is very rare. Setting the address to the 
same as your local netwrok does not make it forward packets there, you'd 
need tap and a bridge for that so unless you really know what your're 
doing you probably can omit these options too.

- Finally I think -enable-kvm is an old option and a machine option is 
preferred nowadays instead

- and -L is only needed if your pc-bios dir is not at the default place

So this might just do the same:

qemu-system-ppc -M mac99,via=pmu,accel=kvm -m 2048 \
  -drive file=/srv/Qemu/debian_32bit.qcow2,format=qcow2,media=disk \
  -monitor stdio

(also maybe try -m 1024 first which should be big enough and some MacOS 
versions may have problems over 1.5GB, although it should not matter for 
Linux).

I suggest to only add options if they are really needed to keep it simple.

> And that doesn’t work for me (same dmesg output about illegal instructions).
>
> It’s really interesting that your kernel is a lot older than mine. I would 
> avoid updating it if you want to keep using KVM!
>
> I also found this thread which looks like too much of a coincidence to me:
>
> https://forum.hyperion-entertainment.com/viewtopic.php?p=50845#p50845

So you have a version to try and a patch to test with later versions at 
least. That limits the number of tries to a managable number.

> I’m going to try and install 5.6.14 and see if I can get it to work.
>
> Thanks for your help. This is beginning to feel more like a kernel / kvm issue 
> than a Qemu one.

In case you end up needing to bisect the kernel later it would be nice if 
somebody could automate this. There's "git bisect run" but it needs a 
script to compile and install kernel then test qemu. Since Macs can 
net-boot you could even do it cross-compiling and remotely but setting it 
up would probably take some setup and script writing. Is this something 
somebody has done already? I think this is a common problem for Linux 
kernel testing.

Regards,
BALATON Zoltan