On 03/06/16 21:36, Markus Armbruster wrote: > Alexey Kardashevskiy <a...@ozlabs.ru> writes: > >> On 03/06/16 16:40, Markus Armbruster wrote: >>> Commit 09aa9a5 "spapr-pci: enable adding PHB via -device" set >>> cannot_instantiate_with_device_add_yet without also adding a comment >>> explaining why. It is currently the only one lacking such a comment. >>> Let's fix that. >>> >>> Unfortunately, the commit message doesn't tell me (or I'm too dense to >>> understand it): >>> >>> spapr-pci: enable adding PHB via -device >>> >>> Recent changes introduced cannot_instantiate_with_device_add_yet >>> and removed capability of adding yet another PCI host bridge via >>> command line for SPAPR platform (POWERPC64 server). >>> >>> This brings the capability back and puts SPAPR PHB into "bridge" >>> category. >>> >>> This is not much use for emulated PHB but it is absolutely required >>> for VFIO as we put an IOMMU group onto a separate PHB on SPAPR. >>> >>> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> >>> Signed-off-by: Alexander Graf <ag...@suse.de> >>> >>> Alexey, can you explain why the device cannot be used with -device / >>> device_add? >> >> It can be used with "-device" with as it is today, i.e. with >> "cannot_instantiate_with_device_add_yet=false". > > I misread the code. But the assignment needs an explanation anyway :)
imho at that moment it was pretty valid :) Now we do not even have to have multiple PHBs on spapr, although we still support this ;) > >> With "cannot_instantiate_with_device_add_yet=true", I get this: >> >> qemu-system-ppc64: -device spapr-pci-host-bridge,id=phb10,index=10: >> Parameter 'driver' expects pluggable device type >> >> >> At that moment (sha1 09aa9a526a86fd2e380e86^) it failed because of >> inherited "cannot_instantiate_with_device_add_yet=true" from >> sysbus_device_class_init() (which is gone now): >> >> qemu-system-ppc64: -device spapr-pci-host-bridge,id=phb10,index=10: >> Parameter 'driver' expects pluggable device type >> >> So there was my patch. >> >> >> "device_add" is different, it does not work because: >> (qemu) device_add spapr-pci-host-bridge >> Bus 'main-system-bus' does not support hotplugging >> >> Which I am not sure if it is true for all platforms or just spapr/ppc64 but >> I do not care much now as there is some work to do anyway to support PHB >> hotplug as per LoPAPR specification anyway. >> >> Does this help? :) > > Now you made me read the code more carefully, I have different > questions. > > Can we delete the assignment? -device > spapr-pci-host-bridge,id=phb10,index=10 still works for me then. _Now_ we can indeed as the default has changed, this works for me too, I just forgot to mention this, sorry. > > If not, why? > -- Alexey
