Re: [PATCH v9 01/10] s390x/cpus: Make absence of multithreading clear

[Cédric Le Goater]

On 9/5/22 17:10, Pierre Morel wrote:
> On 9/5/22 13:32, Nico Boehr wrote:
> > Quoting Pierre Morel (2022-09-02 09:55:22)
> > > S390x do not support multithreading in the guest.
> > > Do not let admin falsely specify multithreading on QEMU
> > > smp commandline.
> > >
> > > Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> > > ---
> > >   hw/s390x/s390-virtio-ccw.c | 3 +++
> > >   1 file changed, 3 insertions(+)
> > >
> > > diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> > > index 70229b102b..b5ca154e2f 100644
> > > --- a/hw/s390x/s390-virtio-ccw.c
> > > +++ b/hw/s390x/s390-virtio-ccw.c
> > > @@ -86,6 +86,9 @@ static void s390_init_cpus(MachineState *machine)
> > >       MachineClass *mc = MACHINE_GET_CLASS(machine);
> > >       int i;
> > > +    /* Explicitely do not support threads */
> >            ^
> >            Explicitly
> >
> > > +    assert(machine->smp.threads == 1);
> >
> > It might be nicer to give a better error message to the user.
> > What do you think about something like (broken whitespace ahead):
> >
> >      if (machine->smp.threads != 1) {if (machine->smp.threads != 1) {
> >          error_setg(&error_fatal, "More than one thread specified, but 
> > multithreading unsupported");
> >          return;
> >      }
>
>
> OK, I think I wanted to do this and I changed my mind, obviously, I do not 
> recall why.
> I will do almost the same but after a look at error.h I will use 
> error_report()/exit() instead of error_setg()/return as in:
>
>
> +    /* Explicitly do not support threads */
> +    if (machine->smp.threads != 1) {
> +        error_report("More than one thread specified, but multithreading 
> unsupported");
> +        exit(1);
> +    }


or add an 'Error **errp' parameter to s390_init_cpus() and use error_setg()
as initially proposed. s390x_new_cpu() would benefit from it also.

Thanks,

C.


> Thanks,
>
> Regards,
> Pierre