On Fri, 22 Jul 2016 12:11:11 +0200
Greg Kurz <gr...@kaod.org> wrote:
> On Fri, 22 Jul 2016 10:04:35 +0200
> Cornelia Huck <cornelia.h...@de.ibm.com> wrote:
>
> > On Thu, 21 Jul 2016 23:21:16 +0200
> > Greg Kurz <gr...@kaod.org> wrote:
> >
> > > From: Greg Kurz <gk...@linux.vnet.ibm.com>
> > >
> > > Without presuming if we got there because of a user mistake or some
> > > more subtle bug in the tooling, it really does not make sense to
> > > implement a non-functional device.
> > >
> > > Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com>
> > > Reviewed-by: Marcel Apfelbaum <mar...@redhat.com>
> > > Signed-off-by: Greg Kurz <gr...@kaod.org>
> > > ---
> > > v4: - rephrased error message and provide a hint to the user
> > > - split string literals to stay below 80 characters
> > > - added Marcel's R-b tag
> > > ---
> > > hw/virtio/virtio-pci.c | 8 ++++++++
> > > 1 file changed, 8 insertions(+)
> > >
> > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > > index 755f9218b77d..72c4b392ffda 100644
> > > --- a/hw/virtio/virtio-pci.c
> > > +++ b/hw/virtio/virtio-pci.c
> > > @@ -1842,6 +1842,14 @@ static void virtio_pci_dc_realize(DeviceState
> > > *qdev, Error **errp)
> > > VirtIOPCIProxy *proxy = VIRTIO_PCI(qdev);
> > > PCIDevice *pci_dev = &proxy->pci_dev;
> > >
> > > + if (!(virtio_pci_modern(proxy) || virtio_pci_legacy(proxy))) {
> >
> > I'm not sure that I didn't mess up the sequence of the realize
> > callbacks, but could disable_legacy still be AUTO here? In that case,
> > we'd fail for disable-modern=on and disable-legacy unset (i.e., AUTO),
> > which would be ok for pcie but not for !pcie.
> >
>
> Marcel made the same comment in:
>
> https://lists.gnu.org/archive/html/qemu-devel/2016-07/msg05225.html
>
> If the user explicitly disables modern, she shouldn't rely on QEMU
> implicitly enabling legacy, hence the suggestion in error_append_hint().
I don't know, I'd find that a bit surprising, especially as I would end
up with a legacy-capable device if I did not specify anything in
the !pcie case.
>
> > > + error_setg(errp, "device cannot work when both modern and legacy
> > > modes"
> > > + " are disabled");
Suggest to change this wording to:
"device cannot work as neither modern nor legacy mode is enabled"
as this more accurately reflects what happened (the user did not
actively disable legacy in the case above).
> > > + error_append_hint(errp, "Set either disable-modern or
> > > disable-legacy"
> > > + " to off\n");
The hint looks fine to me :)
> > > + return;
> > > + }
> > > +
> > > if (!(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_PCIE) &&
> > > virtio_pci_modern(proxy)) {
> > > pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
> > >
> >
>
