Re: [Qemu-discuss] No start with -cpu option

[Thomas]

Hi Peter!

Thanks for your quick answer.

Aug 6, 2019, 7:02 PM by address@hidden:

> On Tue, 6 Aug 2019 at 17:32, Thomas <address@hidden> wrote:
>
>> [...] I tried to start qemu:
>> > qemu-system-ppc -boot d -machine mac99,via=pmu -cpu '7447a_v1.2' -m 1G 
>> > -hda root.img -cdrom install-powerpc-minimal-20190720T101002Z.iso -g 
>> > 1280x854x32
>>
>> But the system does not start. In the console I get only
>> > VNC server running on ::1:5900
>>
>> And one core is used for 100%. Do I connect via vnc I get en maybe
>> 640x480 black window which shows the message:
>> > Guest has not initialized the display (yet).
>>
>
> This usually means "QEMU is running fine, but the guest has
> crashed fatally before it got round to doing anything with
> the graphics".
>
>
OK. In this case OpenBios PPC should be the culprit, shouldn't
it? It is the first to start.

I get only "Guest has not..." message if I try:
> qemu-system-ppc -machine mac99,via=pmu -m 1G -hda root.img -g 1280x854x32 
> -cpu 7447a_v1.2

But I get to the OpenBios prompt without -cpu
> qemu-system-ppc -machine mac99,via=pmu -m 1G -hda root.img -g 1280x854x32

Yes, it seems the problem has nothing to do with the iso. Good
to know.


>
>  In this case the most likely reason is that
> your guest is not able to run with the CPU type you're trying
> to specify -- in that case the solution would be to use a different
> guest image that can boot on this CPU.
>
Hmm, it will be hard to get another OpenBios. The PPC arch in 
https://github.com/openbios/openbios/tree/master/arch/ppc/qemu 
<https://github.com/openbios/openbios/tree/master/arch/ppc/qemu>
had not much activity in the last years. I can try to get in contact
with the folks there but for now I think I'm stuck with the default
CPU.


> It's also possible that QEMU's definition of the 7447a_v1.2
> CPU type is just wrong (missing some feature the real hardware
> has, perhaps). If you wanted to try to debug this you could
> use QEMU's gdbstub and a ppc-aware gdb to debug the guest
> to see where it goes wrong, but this is pretty hairy stuff
> if you're not familiar with debugging OS/bootloader code.
>
I'm definitetly not familiar with gdb debugging. But if someone is
interested in the problem and wants to be a tutor I'm up for the job.
I'm always up to learn something new.

>
> Why do you care about the exact CPU type here? If the default
> one QEMU uses for this machine model works with your guest
> image, why not just use it?
>
I get compile errors on a PowerBook G4 which I try to debug.
Unfortunately I have only limited access to the hardware and
hope I can use a virtual Qemu machine for this instead.
My first goal was to run a virtual machine as close as possible
to the PowerBook. So I found this problem. It was worth a try
to check if it's an easy one. It doesn't seem so therefore I
try the default CPU in the first run.

Thanks again for your quick answer!

Thomas