On Thu, Jul 16, 2020 at 04:57:54PM +0200, Greg Kurz wrote: > On Thu, 16 Jul 2020 16:23:52 +0200 > Markus Armbruster <[email protected]> wrote: > > > David Gibson <[email protected]> writes: > > > > > On Thu, Jul 16, 2020 at 12:32:44PM +0200, Greg Kurz wrote: > > >> On Thu, 16 Jul 2020 14:45:40 +1000 > > >> David Gibson <[email protected]> wrote: > > >> > > >> > On Thu, Jul 09, 2020 at 07:12:47PM +0200, Greg Kurz wrote: > > >> > > Some recent error handling cleanups unveiled issues with our support > > >> > > of > > >> > > PCI bridges: > > >> > > > > >> > > 1) QEMU aborts when using non-standard PCI bridge types, > > >> > > unveiled by commit 7ef1553dac "spapr_pci: Drop some dead error > > >> > > handling" > > >> > > > > >> > > $ qemu-system-ppc64 -M pseries -device pcie-pci-bridge > > >> > > Unexpected error in object_property_find() at qom/object.c:1240: > > >> > > qemu-system-ppc64: -device pcie-pci-bridge: Property '.chassis_nr' > > >> > > not found > > >> > > Aborted (core dumped) > > >> > > > >> > Oops, I thought we had a check that we actually had a "pci-bridge" > > >> > device before continuing with the hotplug, but I guess not. > > >> > > >> Ah... are you suggesting we should explicitly check the actual type > > >> of the bridge rather than looking for the "chassis_nr" property ? > > > > > > Uh.. I thought about it, but I don't think it matters much which way > > > we do it. > > > > Would it make sense to add the "chassis_nr" property to *all* PCI > > bridge devices? > > > > I see that the "PCI Express to PCI/PCI-X Bridge Specification" mentions > a "Chassis Number Register" which looks very similar to the what exists > in standard PCI-to-PCI brdiges. This doesn't seem to be implemented in > our "pcie-pci-bridge" device model though, but of course I have no idea > why :)
We could consider it, but I don't think there's a lot to be gained by
it at this stage. I don't think there's really any reason to want to
use bridges other than plain "pci-bridge" on the pseries machine.
PCI is a bit weird on pseries, since it's explicitly paravirt.
Although you can use extended config space, and thereby PCI-E devices
on it, the topology really looks pretty much identical to vanilla
PCI. So, I don't think there's any reason to use PCI-E bridges on
pseries.
Other than PCI-E bridges of various sorts, a quick scan suggests all
the other bridge types in qemu are weird variants that are mostly
specific to some particular platform. I don't see any reason we'd
want those on pseries either.
> Maybe Michael or Marcel (cc'd) can share some thoughts about that ?
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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