25.05.2020 21:45, Thomas Huth wrote: > On 29/04/2020 18.43, Michael Tokarev wrote: >> Hi! >> >> Just a fun case of (invalid) usage of qemu-system command line. >> Someone tried -nic model=rocker, and qemu does this: >> >> Unexpected error in object_property_find() at >> /build/qemu/git/qom/object.c:1029: >> qemu-system-x86_64: Property '.mac' not found >> Aborted >> >> This happens after this commit: >> >> commit 52310c3fa7dc854dd2376ae8a518141abcdb78f3 >> Author: Paolo Bonzini <pbonz...@redhat.com> >> Date: Fri Mar 2 10:30:50 2018 +0100 >> >> net: allow using any PCI NICs in -net or -nic >> >> Previously rocker rightly wasn't usable as a nic model, >> and after this commit it is now possible. >> >> While I agree this is invalid usage, perhaps qemu should not >> abort like this? Maybe it should check the required property >> too, before allowing this device to be a nic model? > > QEMU theoretically should never abort() - abort() means there is > something wrong in the code ... so we should definitely fix this by > other means. Some questions: > > 1) How is that rocker device normally used? Similar to a normal network > card? Or completely different?
Nope, this is not a network card, it is a network SWITCH, used as a regular PCI device, not network-specific. Hence the problem at hand, - before the patch this device weren't "nic-able", so to say, because while it is network-related PCI device, it is not a NIC. I guess while building a list of "nic-able" cards, we should skip some "nic-alike" devices and use some more specific criteria. Not everything which is network-related is a regular NIC. Maybe in time some other devices will appear in qemu with similar effect which will require another condition. Or adding a new field into the pci structure to indicate this device can be a NIC will solve it once for all. Or just reverting the patch :) - after all it isn't that bad to have a list of NIC-able devices outside of the device definitions, - we don't have tons of devices anyway where maintaining such a list outside of device model is a problem. Thanks, /mjt > 2) In case it is similar to a normal network card, would it make sense > to allow it with -nic or -net, too? Or should we simply disallow it > here? I think we could either use a list of devices that should never be > allowed here, or we check for the availability of that "mac" property... > > Thomas >
