Re: [PATCH 2/3] qemu: capabilities: Condemn the use of 'device.json' capability name

On a Monday in 2022, Peter Krempa wrote: > As a workaround for users using 'libvirt-7.9' and 'libvirt-7.10' with > 'qemu-6.2' who wish to use device hot-unplug we are going to be > suggesting to filter out the 'device.json' qemu capability via either > the global 'qemu.conf' config: > > capability_filters = [ "device.json" ] > > or the per-VM XML capability override: > > <domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'> > > [...] > > <qemu:capabilities> > <qemu:del capability='device.json'/> > </qemu:capabilities> > </domain> > > Doing this poisons the capability name 'device.json' for any further > use, so to ensure that we can re-add JSON usage for -device also for > users which filtered it out originally once it's fixed in qemu we need > to condemn the old name and add a new one. > > To achieve this the old capability is renamed to > 'X_QEMU_CAPS_DEVICE_JSON_BROKEN' and a new capability > 'QEMU_CAPS_DEVICE_JSON' is mapped to 'device.json-fixed'. For now we I am not a fan of the new string but we can change it later once it's clear how to probe for this in QEMU.