Re: [Qemu-devel] QEMU: PCI bus name on PowerPC platforms

[Andreas Färber]

Am 05.03.2014 15:35, schrieb Andreas Färber:
> Am 05.03.2014 15:21, schrieb Daniel P. Berrange:
>> On Wed, Mar 05, 2014 at 03:12:40PM +0100, Paolo Bonzini wrote:
>>> Il 05/03/2014 14:40, Daniel P. Berrange ha scritto:
>>>> FWIW, I had requested this rename in the past but it was rejected :-(
>>>>
>>>>    http://comments.gmane.org/gmane.comp.emulators.qemu/70783
>>>
>>> I think we should revisit that.
>>>
>>> Path-based bus names are a good idea, but unfortunately it's not how 
>>> things ended up working.
>>>
>>> We now have two namespaces:
>>>
>>> - one based on the device id + incremental number, where things created
>>> by the user can be addressed in a forwards-compatible way
>>>
>>> - another based on the bus type as soon as Alex/Markus's patch "qdev:
>>> Keep global allocation counter per bus", for things created by the board
>>> (and also by the user, but with no forwards guarantee of compatibility).
>>>
>>> So we could respin your patch, but with NULL bus name instead of "pci.0".
>>> Just a handful of machines are affected:
>>>
>>> alpha/typhoon.c:    b = pci_register_bus(dev, "pci",
>>> mips/gt64xxx_pci.c:     phb->bus = pci_register_bus(dev, "pci",
>>> pci-host/apb.c:    phb->bus = pci_register_bus(DEVICE(phb), "pci",
>>> pci-host/bonito.c:    phb->bus = pci_register_bus(DEVICE(dev), "pci",
>>> sh4/sh_pci.c:    phb->bus = pci_register_bus(DEVICE(dev), "pci",
>>> pci-host/versatile.c:    pci_bus_new_inplace(&s->pci_bus, 
>>> sizeof(s->pci_bus), DEVICE(obj), "pci",
>>>
>>> plus pseries which has its own rules because it supports multiple PCI
>>> host bridges, but probably can also be changed from "pci" to NULL.
>>
>> I'm not sure I understand the effect of changing 'pci' to NULL in this
>> code, from libvirt's POV. Would using NULL mean we can rely on using
>> "pci.0" as the default PCI bus name or not ?
> 
> I believe so, yes. See
> https://github.com/afaerber/qemu-cpu/commit/ce1c9b4302a4458e73ae6a6a13f4e4ee121f79ea

Err, on second thoughts that depends on the device not having an id=. If
it does, then it's foo.0, not pci.0.

Andreas


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