On Fri, 11 Jan 2019 01:06:45 +0400
Marc-André Lureau <marcandre.lur...@gmail.com> wrote:
> On Thu, Jan 10, 2019 at 10:07 PM Eduardo Habkost <ehabk...@redhat.com> wrote:
> >
> > On Thu, Jan 10, 2019 at 03:01:25PM +0000, Dr. David Alan Gilbert wrote:
> > > * Michael S. Tsirkin (m...@redhat.com) wrote:
> > > > On Thu, Jan 10, 2019 at 11:31:23AM -0200, Eduardo Habkost wrote:
> > > > > On Thu, Jan 10, 2019 at 12:35:26PM +0400, Marc-André Lureau wrote:
> > > > > > Hi
> > > > > >
> > > > > > On Thu, Jan 10, 2019 at 6:05 AM Eduardo Habkost
> > > > > > <ehabk...@redhat.com> wrote:
> > > > > > >
> > > > > > > The disable-legacy and disable-modern properties apply only to
> > > > > > > some virtio-pci devices. Make those properties optional.
> > > > > > >
> > > > > > > This fixes the crash introduced by commit f6e501a28ef9 ("virtio:
> > > > > > > Provide
> > > > > > > version-specific variants of virtio PCI devices"):
> > > > > > >
> > > > > > > $ qemu-system-x86_64 -machine pc-i440fx-2.6 \
> > > > > > > -device virtio-net-pci-non-transitional
> > > > > > > Unexpected error in object_property_find() at qom/object.c:1092:
> > > > > > > qemu-system-x86_64: -device virtio-net-pci-non-transitional:
> > > > > > > can't apply \
> > > > > > > global virtio-pci.disable-modern=on: Property '.disable-modern'
> > > > > > > not found
> > > > > > > Aborted (core dumped)
> > > > > > >
> > > > > > > Reported-by: Thomas Huth <th...@redhat.com>
> > > > > > > Fixes: f6e501a28ef9 ("virtio: Provide version-specific variants
> > > > > > > of virtio PCI devices")
> > > > > > > Signed-off-by: Eduardo Habkost <ehabk...@redhat.com>
> > > > > > > ---
> > > > > > > hw/core/machine.c | 5 +++--
> > > > > > > 1 file changed, 3 insertions(+), 2 deletions(-)
> > > > > > >
> > > > > > > diff --git a/hw/core/machine.c b/hw/core/machine.c
> > > > > > > index 5530b71981..a19143aa44 100644
> > > > > > > --- a/hw/core/machine.c
> > > > > > > +++ b/hw/core/machine.c
> > > > > > > @@ -91,8 +91,9 @@ const size_t hw_compat_2_7_len =
> > > > > > > G_N_ELEMENTS(hw_compat_2_7);
> > > > > > >
> > > > > > > GlobalProperty hw_compat_2_6[] = {
> > > > > > > { "virtio-mmio", "format_transport_address", "off" },
> > > > > > > - { "virtio-pci", "disable-modern", "on" },
> > > > > > > - { "virtio-pci", "disable-legacy", "off" },
> > > > > > > + /* Optional because not all virtio-pci devices support
> > > > > > > legacy mode */
> > > > > > > + { "virtio-pci", "disable-modern", "on", .optional = true },
> > > > > > > + { "virtio-pci", "disable-legacy", "off", .optional = true },
> > > > > > >
> > > > > >
> > > > > > Could the generic devices implement a specific interface instead?
> > > > > > virtio-pci-generic?
> > > > >
> > > > > This is the kind of complexity I wanted to avoid. We already
> > > > > have too many interface names for subsets of PCI and virtio
> > > > > devices.
> > > > >
> > > > > >
> > > > > > Adding "optional" handling looks like it may hide some other
> > > > > > errors.
> > > > >
> > > > > What if we just make "optional" mean "skip if the property
> > > > > doesn't exist", as suggested by Cornelia and Dave?
> > > >
> > > > That's the more standard meaning of the word optional, isn't it?
> > >
> > > Well the word is a separate issue; 'optional' is probably a bad choice
> > > but that's less important than what it actually does.
> > > I'd go for skip_if_missing which is explicit.
> >
> > I'm unsure about that. To me "optional" means "it can be
> > missing" and carries the same information as "skip if missing".
> >
> > What do others think?
>
> skip_if_missing is more explicit.
I'd slightly prefer optional, but skip_if_missing is fine.
