Re: [PATCH] hw/riscv: virt: Warn the user if -bios is provided when using KVM

[Alistair Francis <alistair23@gmail.com>]

On Thu, Mar 24, 2022 at 7:08 PM Daniel P. Berrangé <berrange@redhat.com> wrote:
>
> On Wed, Mar 23, 2022 at 06:13:46PM +0100, Ralf Ramsauer wrote:
> > The -bios option is silently ignored if used in combination with -enable-kvm.
> > The reason is that the machine starts in S-Mode, and the bios typically runs in
> > M-Mode.
> >
> > Warn the user that the bios won't be loaded.
> >
> > Signed-off-by: Ralf Ramsauer <ralf.ramsauer@oth-regensburg.de>
> > ---
> >  hw/riscv/virt.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
> > index 4496a15346..a4d13114ee 100644
> > --- a/hw/riscv/virt.c
> > +++ b/hw/riscv/virt.c
> > @@ -1312,6 +1312,9 @@ static void virt_machine_init(MachineState *machine)
> >       * when KVM is enabled.
> >       */
> >      if (kvm_enabled()) {
> > +        if (machine->firmware && strcmp(machine->firmware, "none"))
> > +            warn_report("BIOS is not supported in combination with KVM. "
> > +                        "Ignoring BIOS.");
>
> If the usage scenario isn't supportable, then ultimately we should be
> raising an error and immediately exiting.
>
> If you know of common usage that is already mistakenly passing -bios,
> then we could start with a warning and list it as deprecated, then
> change to an error_report 2 releases later. If we don't thing people
> are often mistakenly passing -bios, then go straight for error_report
> and exit.

That's a good point. The original thinking was that we did support
-bios and so we should warn the user that it's unlikely they want to
use it. This would still allow S mode UEFI loaders to be used (they
don't exist today).

Considering we are currently just ignoring the option I agree it's
better to report an error.

Do you mind sending a v2 Ralf?

Alistair

>
> >          g_free(machine->firmware);
> >          machine->firmware = g_strdup("none");
> >      }
> > --
> > 2.32.0
> >
> >
>
> With regards,
> Daniel
> --
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>