Re: Request for New PPC Machine Supporting Multiple SMP Cores

[Peter Maydell]

On Thu, 7 Dec 2023 at 17:40, BALATON Zoltan <balaton@eik.bme.hu> wrote:
>
> On Thu, 7 Dec 2023, aziz tlili wrote:
> > Dear QEMU Team,
> >
> > I hope this message finds you well. I've been a user of QEMU for well over
> > a year.
> >
> > I wanted to share an idea for a potential enhancement that I believe could
> > benefit many users, including myself. It would be fantastic to have a new
> > PPC machine model similar to the existing mac99, but with support for
> > multiple SMP cores for both qemu-system-ppc and qemu-system-ppc64.
>
> There are several machines in qemu-system-ppc64 that support SMP such as
> pseries and powernv I think. For qemu-system-ppc maybe only ppce500. The
> mac99 may create multiple CPUs (G4 when ron with qemu-system-ppc or G5
> with qemu-system-ppc64) but not sure if there's an OS that can actually
> use that. Linux support for mac99 may not be the best.

I think our mac99 machine refuses to create more than one CPU, because
it sets mc->max_cpus to 1 in core99_machine_class_init(). This in
turn is probably because nobody has ever implemented and tested
whatever the SMP support handling would need to be for this machine
type.

> Problem is not in understanding the potential advantages but the lack of
> people interested in working on that so progress depends on somebody doing
> it and sending patches.

Entirely agreed. This is a feature request from two years ago about
adding SMP support to the newworld machines:
 https://gitlab.com/qemu-project/qemu/-/issues/672
Nobody has done that work in two years, but anybody who has the
interest and time to do so is welcome to.

thanks
-- PMM