Re: [Qemu-devel] [PATCH 1/2 v2] pci: change default value of rom_bar to 2

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Feb 19, 2014 at 01:36:45PM -0700, Alex Williamson wrote:
> On Wed, 2014-02-19 at 15:20 -0500, Bandan Das wrote:
> > The following patch depends on the value of rom_bar to
> > determine rom blacklist behavior. Existing code shouldn't
> > be affected by changing the default value of rom_bar since
> > all relevant decisions only rely on whether rom_bar is zero
> > or non-zero.
> > 
> > Signed-off-by: Bandan Das <bsd@redhat.com>
> > ---
> >  hw/pci/pci.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > index 4e0701d..12c3e27 100644
> > --- a/hw/pci/pci.c
> > +++ b/hw/pci/pci.c
> > @@ -53,7 +53,12 @@ static void pci_bus_finalize(Object *obj);
> >  static Property pci_props[] = {
> >      DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
> >      DEFINE_PROP_STRING("romfile", PCIDevice, romfile),
> > -    DEFINE_PROP_UINT32("rombar",  PCIDevice, rom_bar, 1),
> > +    /*
> > +     * 0 = disable
> > +     * 1 = user requested on, force loading even if rom blacklisted
> > +     * 2 = enabled but disables loading of blacklisted roms (default)
> > +     */
> > +    DEFINE_PROP_UINT32("rombar",  PCIDevice, rom_bar, 2),
> >      DEFINE_PROP_BIT("multifunction", PCIDevice, cap_present,
> >                      QEMU_PCI_CAP_MULTIFUNCTION_BITNR, false),
> >      DEFINE_PROP_BIT("command_serr_enable", PCIDevice, cap_present,
> 
> A slightly more satisfying option might be to define rom_bar as int32_t
> with default of -1.  I don't know if that would break libvirt though.
> I'll let MST weigh in.  Thanks,
> 
> Alex

I don't see rombar in json schema at all.
I think it was designed as an internal flag
for compatibility with legacy machine types.
As such it's likely not a good interface
for users.

-- 
MST