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

[Marcel Apfelbaum <marcel.a@redhat.com>]

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...
 

> 
> -- PMM