Re: [Qemu-devel] [PATCH] Correctly assign PCI domain numbers

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

On Mon, Aug 01, 2011 at 04:51:02PM +1000, David Gibson wrote:
> qemu already almost supports PCI domains; that is, several entirely
> independent PCI host bridges on the same machine.  However, a bug in
> pci_bus_new_inplace() means that every host bridge gets assigned domain
> number zero and so can't be properly distinguished.  This patch fixes the
> bug, giving each new host bridge a new domain number.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

OK, but I'd like to see the whole picture.
How does the guest detect multiple domains,
and how does it access them?

> ---
>  hw/pci.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
> 
> diff --git a/hw/pci.c b/hw/pci.c
> index 36db58b..2b4aecb 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -262,6 +262,8 @@ int pci_find_domain(const PCIBus *bus)
>      return -1;
>  }
>  
> +static int pci_next_domain; /* = 0 */
> +
>  void pci_bus_new_inplace(PCIBus *bus, DeviceState *parent,
>                           const char *name,
>                           MemoryRegion *address_space,
> @@ -274,7 +276,8 @@ void pci_bus_new_inplace(PCIBus *bus, DeviceState *parent,
>  
>      /* host bridge */
>      QLIST_INIT(&bus->child);
> -    pci_host_bus_register(0, bus); /* for now only pci domain 0 is supported */
> +
> +    pci_host_bus_register(pci_next_domain++, bus);

What happens when that overflows?

>  
>      vmstate_register(NULL, -1, &vmstate_pcibus, bus);
>  }
> -- 
> 1.7.5.4
>