Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses

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

On Mon, Sep 09, 2013 at 04:29:04PM +0300, Marcel Apfelbaum wrote:
> On Mon, 2013-09-09 at 14:19 +0100, Peter Maydell wrote:
> > On 9 September 2013 14:15, Marcel Apfelbaum <marcel.a@redhat.com> wrote:
> > > On Mon, 2013-09-09 at 14:02 +0100, Peter Maydell wrote:
> > >> Can you just pick the device which is (a subclass of)
> > >> TYPE_PCI_HOST_BRIDGE, or do we have host bridges which
> > >> aren't using that class?
> > > This is what I would really want to do, but some HOST Bridge devices
> > > inherit directly from PCI_DEVICE.
> > 
> > > TYPE_PCI_HOST_BRIDGE derives from TYPE_SYS_BUS_DEVICE which
> > > is a not a PCI device and does not help us here (not a PCI_DEVICE
> > > on the bus)
> > 
> > Oops, yes, I get those two the wrong way round a lot. Anyway,
> > if we need to make all host bridges have a common subclass
> > we could certainly refactor them accordingly.
> > 
> > > Strangely TYPE_Q35_HOST_DEVICE derives from TYPE_SYS_BUS_DEVICE
> > > and it hold as composition a PCIDevice that will be part of
> > > the bus, as opposed to TYPE_I440FX_PCI_DEVICE which directly
> > > inherits from PCI_DEVICE.
> > 
> > This may just be wrong choice of name rather than actually
> > wrong hierarchy.
> I try not to "judge" the naming convention, so let's leave it
> aside for now.
> My issue is that we have at least 2 ways to model the bridges:
> 1. TYPE_PCI_HOST_BRIDGE
>    * derives from TYPE_SYS_BUS_DEVICE
>    * has a bus
>    * one of the bus devices is a TYPE_I440FX_PCI_DEVICE which
>     derives from TYPE_PCI_DEVICE
> 2. TYPE_PCIE_HOST_BRIDGE
>    * derives from TYPE_PCI_HOST_BRIDGE which derives
>      from TYPE_SYS_BUS_DEVICE
>    * has a PciDevice and register it to the bus in order
>      to work as (1)
> 
> I would like to implement an hierarchy that will allow
> all the host bridge devices to have a common ancestor
> In this was, we can scan the PCI bus to look for
> master...

I wouldn't object to is_host is stuct PCIDeviceClass.
That's probably easier that trying to create
a common class for devices that share no common code.


> 
> > 
> > -- PMM
>