Re: [PATCH v2 6/6] hw/isa/piix: Resolve redundant TYPE_PIIX3_XEN_DEVICE

[Philippe Mathieu-Daudé]

On 4/1/23 18:54, Chuck Zmudzinski wrote:
> On 1/4/23 10:35 AM, Philippe Mathieu-Daudé wrote:
> > +Markus/Thomas
> >
> > On 4/1/23 15:44, Bernhard Beschow wrote:
> > > During the last patches, TYPE_PIIX3_XEN_DEVICE turned into a clone of
> > > TYPE_PIIX3_DEVICE. Remove this redundancy.
> > >
> > > Signed-off-by: Bernhard Beschow <shentey@gmail.com>
> > > ---
> > >    hw/i386/pc_piix.c             |  4 +---
> > >    hw/isa/piix.c                 | 20 --------------------
> > >    include/hw/southbridge/piix.h |  1 -
> > >    3 files changed, 1 insertion(+), 24 deletions(-)
> > >
> > > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > > index 5738d9cdca..6b8de3d59d 100644
> > > --- a/hw/i386/pc_piix.c
> > > +++ b/hw/i386/pc_piix.c
> > > @@ -235,8 +235,6 @@ static void pc_init1(MachineState *machine,
> > >        if (pcmc->pci_enabled) {
> > >            DeviceState *dev;
> > >            PCIDevice *pci_dev;
> > > -        const char *type = xen_enabled() ? TYPE_PIIX3_XEN_DEVICE
> > > -                                         : TYPE_PIIX3_DEVICE;
> > >            int i;
> > >    
> > >            pci_bus = i440fx_init(pci_type,
> > > @@ -250,7 +248,7 @@ static void pc_init1(MachineState *machine,
> > >                                           : pci_slot_get_pirq);
> > >            pcms->bus = pci_bus;
> > >    
> > > -        pci_dev = pci_new_multifunction(-1, true, type);
> > > +        pci_dev = pci_new_multifunction(-1, true, TYPE_PIIX3_DEVICE);
> > >            object_property_set_bool(OBJECT(pci_dev), "has-usb",
> > >                                     machine_usb(machine), &error_abort);
> > >            object_property_set_bool(OBJECT(pci_dev), "has-acpi",
> > > diff --git a/hw/isa/piix.c b/hw/isa/piix.c
> > > index 98e9b12661..e4587352c9 100644
> > > --- a/hw/isa/piix.c
> > > +++ b/hw/isa/piix.c
> > > @@ -33,7 +33,6 @@
> > >    #include "hw/qdev-properties.h"
> > >    #include "hw/ide/piix.h"
> > >    #include "hw/isa/isa.h"
> > > -#include "hw/xen/xen.h"
> > >    #include "sysemu/runstate.h"
> > >    #include "migration/vmstate.h"
> > >    #include "hw/acpi/acpi_aml_interface.h"
> > > @@ -465,24 +464,6 @@ static const TypeInfo piix3_info = {
> > >        .class_init    = piix3_class_init,
> > >    };
> > >    
> > > -static void piix3_xen_class_init(ObjectClass *klass, void *data)
> > > -{
> > > -    DeviceClass *dc = DEVICE_CLASS(klass);
> > > -    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
> > > -
> > > -    k->realize = piix3_realize;
> > > -    /* 82371SB PIIX3 PCI-to-ISA bridge (Step A1) */
> > > -    k->device_id = PCI_DEVICE_ID_INTEL_82371SB_0;
> > > -    dc->vmsd = &vmstate_piix3;
> >
> > IIUC, since this device is user-creatable, we can't simply remove it
> > without going thru the deprecation process. Alternatively we could
> > add a type alias:
> >
> > -- >8 --
> > diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
> > index 4b0ef65780..d94f7ea369 100644
> > --- a/softmmu/qdev-monitor.c
> > +++ b/softmmu/qdev-monitor.c
> > @@ -64,6 +64,7 @@ typedef struct QDevAlias
> >                                  QEMU_ARCH_LOONGARCH)
> >    #define QEMU_ARCH_VIRTIO_CCW (QEMU_ARCH_S390X)
> >    #define QEMU_ARCH_VIRTIO_MMIO (QEMU_ARCH_M68K)
> > +#define QEMU_ARCH_XEN (QEMU_ARCH_ARM | QEMU_ARCH_I386)
> >
> >    /* Please keep this table sorted by typename. */
> >    static const QDevAlias qdev_alias_table[] = {
> > @@ -111,6 +112,7 @@ static const QDevAlias qdev_alias_table[] = {
> >        { "virtio-tablet-device", "virtio-tablet", QEMU_ARCH_VIRTIO_MMIO },
> >        { "virtio-tablet-ccw", "virtio-tablet", QEMU_ARCH_VIRTIO_CCW },
> >        { "virtio-tablet-pci", "virtio-tablet", QEMU_ARCH_VIRTIO_PCI },
> > +    { "PIIX3", "PIIX3-xen", QEMU_ARCH_XEN },
>
> Hi Bernhard,
>
> Can you comment if this should be:
>
> +    { "PIIX", "PIIX3-xen", QEMU_ARCH_XEN },
>
> instead? IIUC, the patch series also removed PIIX3 and PIIX4 and
> replaced them with PIIX. Or am I not understanding correctly?

There is a confusion in QEMU between PCI bridges, the first PCI
function they implement, and the other PCI functions.

Here TYPE_PIIX3_DEVICE means for "PCI function part of the PIIX
south bridge chipset, which expose a PCI-to-ISA bridge". A better
name could be TYPE_PIIX3_ISA_PCI_DEVICE. Unfortunately this
device is named "PIIX3" with no indication of ISA bridge.