Re: [Qemu-devel] [RFC v5 0/6] pci_expander_brdige: support separate pci domain for pxb-pcie

[Zihan Yang]

Marcel Apfelbaum <address@hidden> 于2018年9月20日周四 下午2:41写道：
>
> Hi Zihan, Gerd
>
> On 09/20/2018 09:09 AM, Gerd Hoffmann wrote:
> >>>> As for the management, will some checks when adding mcfg be enough for
> >>>> management? Or I can maintain a variable to indicate how many space
> >>>> have been consumed and warn the user if they exceed the threshold?
> >>>> The latter allows us to do the check when the pxb-pcie is initializing.
> >>> I think qemu should not apply any restrictions here.
> >> But will that confuse users when their device is not listed in guest os
> >> while qemu does not throw any error/warning?
> > Well, that can happen anyway.  For example when using an old seabios
> > version without pci domain support, or other firmware without pci domain
> > support (coreboot, ovmf).  And there is no easy way for qemu to figure
> > this beforehand.
> >
> > You can detect this later, when generating the acpi tables, that there
> > are expander bridges where the hidden pci bar wasn't configured by the
> > firmware.  Logging a warning in that case - pointing out the missing
> > firmware support - is probably a good idea.
>
> Logging a warning if the pxb-pci was not configured is enough I think.
> It will also help in case QEMU uses other firmware not supporting
> multiple PCI domains at all, e.g. OVMF  (for now), or an older SeaBIOS.

OK, will be added in next version.

>
> Thanks,
> Marcel
>
> > cheers,
> >    Gerd
> >
>