Re: [Qemu-devel] [RFC v2 3/6] pci: Rename and change signatures of pci_bus_new() & related functions

[Eduardo Habkost <ehabkost@redhat.com>]

On Wed, Apr 19, 2017 at 09:41:42AM +0100, Peter Maydell wrote:
> On 18 April 2017 at 23:17, Eduardo Habkost <ehabkost@redhat.com> wrote:
> > pci_bus_new*() and pci_register_bus() work only when the 'parent'
> > argument is a PCI_HOST_BRIDGE object. Rename them to reflect that they
> > are meant to initialize a bus that's in a PCI host bridge.
> >
> > The new function names are:
> > * pci_host_bus_init() (replacing pci_bus_new())
> > * pci_host_bus_init_inplace() (replacing pci_bus_new_inplace())
> > * pci_host_bus_init_irqs() (replacing pci_register_bus())
> 
> This is moving these functions away from the convention that
> we seem to mostly follow for buses (eg ISA, SCSI) of
> foo_bus_new() to allocate and return a new bus, and
> foo_bus_new_inplace() to initialize a bus that's inline in
> some other struct.
> 
> I'm not sure this is a good idea unless we have a plan to
> convert all the other QOM buses and document that this is
> the right way to implement init for a bus.

The point of the rename is that those functions are doing more
than just allocating a PCIBus. They do some initialization of
PCIHostState as well. That's why non-root PCI buses can't be
created by pci_bus_new*() today.

Maybe the answer here is to move the PCI_HOST_BRIDGE-specific
code somewhere else, and make pci_bus_new*() more generic. This
would allow us to reuse pci_bus_new*() when creating non-root PCI
buses, later.

-- 
Eduardo