Re: [Qemu-devel] [Qemu-trivial] [PATCH v2] serial-pci: Set prog interface field of pci config to 16550 compatible

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

On Wed, May 14, 2014 at 01:39:03AM +0200, BALATON Zoltan wrote:
> On Thu, 8 May 2014, Michael Tokarev wrote:
> >27.02.2014 05:05, BALATON Zoltan wrote:
> >
> >Shoudl we actually make it machine-specific, to keep even prog-if value
> >of these things the same as before for older machine types?  I dunno.
> >mst says we should, I think this is not a very important property to keep.
> 
> So what's the decision? Can it be taken as it is now or do you want
> any more changes? (If you want it version specific then please tell
> me how to do that or show me an example because I don't know how to
> do that.)
> 
> Regards,
> BALATON Zoltan

If you change it migration to old qemu breaks.

See
commit aa93200b88fb1071eaf21bf766711762ed4630e2
Author: Gabriel L. Somlo <gsomlo@gmail.com>
Date:   Mon May 5 10:52:51 2014 -0400

    apic: use emulated lapic version 0x14 on pc machines >= 2.1
as an example on how to do it.

> >
> >Thanks,
> >
> >/mjt
> >
> >> v2: resubmission after pc-2.1 is added with the multiport case
> >>
> >> hw/char/serial-pci.c | 2 ++
> >> 1 file changed, 2 insertions(+)
> >>
> >>diff --git a/hw/char/serial-pci.c b/hw/char/serial-pci.c
> >>index 991c99f..f3f5e07 100644
> >>--- a/hw/char/serial-pci.c
> >>+++ b/hw/char/serial-pci.c
> >>@@ -60,6 +60,7 @@ static int serial_pci_init(PCIDevice *dev)
> >>         return -1;
> >>     }
> >>
> >>+    pci->dev.config[PCI_CLASS_PROG] = 0x02; /* 16550 compatible */
> >>     pci->dev.config[PCI_INTERRUPT_PIN] = 0x01;
> >>     s->irq = pci_allocate_irq(&pci->dev);
> >>
> >>@@ -101,6 +102,7 @@ static int multi_serial_pci_init(PCIDevice *dev)
> >>     assert(pci->ports > 0);
> >>     assert(pci->ports <= PCI_SERIAL_MAX_PORTS);
> >>
> >>+    pci->dev.config[PCI_CLASS_PROG] = 0x02; /* 16550 compatible */
> >>     pci->dev.config[PCI_INTERRUPT_PIN] = 0x01;
> >>     memory_region_init(&pci->iobar, OBJECT(pci), "multiserial", 8 * pci->ports);
> >>     pci_register_bar(&pci->dev, 0, PCI_BASE_ADDRESS_SPACE_IO, &pci->iobar);
> >>
> >
> >