Re: [Qemu-devel] [PATCH V2 0/4] hw/pcie: Multi-root support for Q35

[Marcel Apfelbaum]

On 11/16/2015 12:11 PM, Paolo Bonzini wrote:
> On 16/11/2015 11:10, Marcel Apfelbaum wrote:
> > > What would you lose?  Hotplug?
> >
> > Without the bridge? Yes. However the user can add it manually the
> > pci-bridge and have it anyway.
>
> Ok, I guess that's more or less acceptable.  It's still ugly however, to
> the point that I wonder if we should rename the device and call the old
> one a failed experiment.

I guess we can rename the pxb to extra-root or something, but in this way
will have a deprecated/duplicated device to support and kill in the future.

Why not use the compat property as it is?
Again, the command line *remains* the same, the difference is where the
devices associated with the pxb will land: on the secondary bus (for QEMU < 2.5)
or on the root bus itself (QEMU >= 2.5).

I know is guest visible, but the guest will see one of them depending on the 
machine type.

Regarding the splitting of pxb into 2 devices (pci/pcie), I have nothing 
against it,
but because the implementation is *exactly* the same I think we should gain more
by maintaining one device.


Thanks,
Marcel


> Paolo
>
> > I wanted to get rid of the internal pci-bridge as a default, and this
> > is why pxb and pxb-pcie are he same device now (except bus type)