Re: Multiple CPU for PPC virtual machine on x86_64 host

[Daniel Henrique Barboza]

On 8/2/22 19:19, BERBAR Florian wrote:
> Hello everyone,
>
> I am working on 32 bit PPC systems on a qemu-ppc based virtual system but I 
> have not been able to boot my virtual machine with multiple CPUs.
>
> My host has the following versions:
> - Linux version 5.10.0-15-amd64 (debian-kernel@lists.debian.org) (gcc-10 
> (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2) #1 
> SMP Debian 5.10.120-1 (2022-06-09)
> - QEMU emulator version 5.2.0 (Debian 1:5.2+dfsg-11+deb11u2)
> Copyright (c) 2003-2020 Fabrice Bellard and the QEMU Project developers
>
> First, I tried to set the -smp option with the number of CPUs with the 
> following command but the default machine type (g3beige) does not support more 
> than one core.
>
> $ qemu-system-ppc -m 2047M -smp 4 -hda -cdrom 
> install-powerpc-minimal-20220122T062244Z.iso -boot d
> qemu-system-ppc: Invalid SMP CPUs 4. The max CPUs supported by machine 
> 'g3beige' is 1
>
>
> Then I also tried to change the machine type based on the list in the help 
> output
>
> $ qemu-system-ppc -M help
> Supported machines are:
> 40p                  IBM RS/6000 7020 (40p)
> bamboo               bamboo
> g3beige              Heathrow based PowerMAC (default)
> mac99                Mac99 based PowerMAC
> mpc8544ds            mpc8544ds
> none                 empty machine
> ppce500              generic paravirt e500 platform
> ref405ep             ref405ep
> sam460ex             aCube Sam460ex
> taihu                taihu
> virtex-ml507         Xilinx Virtex ML507 reference design

The mpc8544ds machine is able to boot with 2 CPUs:

qemu-system-ppc -m 1G -M mpc8544ds -kernel 
./buildroot/qemu_ppc_mpc8544ds-latest/vmlinux \
-net nic,model=e1000 -net user -serial mon:stdio \
-nographic -snapshot -smp 2

This line brings me up to the login prompt.

I can get a e500 guest started with 2 CPUs, but the boot hangs when the
kernel tries to start the second CPU:

qemu-system-ppc -m 1G -M ppce500 -cpu e500mc \
-kernel ./buildroot/qemu_ppc_e500mc-latest/uImage -append "root=/dev/vda" \
-drive file=./buildroot/qemu_ppc_e500mc-latest/rootfs.ext2,if=virtio,format=raw 
\
-net nic,model=virtio-net-pci -net user -serial mon:stdio -nographic -snapshot \
-smp 2

e500 family performance monitor hardware support registered
rcu: Hierarchical SRCU implementation.
smp: Bringing up secondary CPUs ...
(... hangs indefinitely here ...)

So unless you want to debug why this is happening I guess you can stick with
the mpc8544ds machine.


If you want to give it a try by yourself, the kernel and disk images I used 
above
can be found in this repo:

https://github.com/legoater/qemu-ppc-boot


> Then I also tried to change the machine type based on the list in the help 
> output
>
> The mpc8544ds and ppce500 machines give me the "QEMU 5.2.0 monitor" prompt 
> right after starting but I don't really understand why...


This happens because you didn't redirect the serial console of the machine
to the terminal. What you're seeing is the QEMU monitor console.

You can redirect the VM output to the terminal by adding

"-serial mon:stdio -nographic"

In the command line.


Thanks,


Daniel

> Could someone help me to start a PPC virtual machine with more than one CPU?





> Thank you very much
>
> Florian