Daniel P. Berrangé <berra...@redhat.com> writes: > On Thu, May 14, 2020 at 10:40:40AM -0400, John Snow wrote: >> >> >> On 5/14/20 4:56 AM, Daniel P. Berrangé wrote: >> > On Thu, May 14, 2020 at 10:09:21AM +0200, Paolo Bonzini wrote: >> >> IMHO configuration files are in general a failed experiment. In >> >> practice, they do not add much value over just a shell script because >> >> they don't allow configuring all QEMU options, they are very much fixed >> >> (by their nature). I think it's more or less agreed that they are not >> >> solving any problem for higher-level management stacks as well; those >> >> would prefer to configure the VM via QMP or another API. >> >> >> >> So, any objections to deprecating -readconfig and -writeconfig? >> > >> > Libvirt would like to have a config file for QEMU, but it would have >> > to be one that actually covers all the config options QEMU supports, >> > and ideally using a data format in common with that used for runtime >> > changes. So for libvirt's needs the current readconfig is entirely >> > useless. >> > >> >> Yeah. In this sense, would a json/yaml config file help, under the >> premise that you could just cat it into the pipe to configure a machine? >> >> (Assuming we had proper runtime configuration commands, of course.) > > Yeah, the key thing is that you really want to be able to provide the > whole initial config in one go as an atomic action. I don't want to > issue 100 individual QMP commands to load each initial device. With > that in mind it doesn't really matter whether you do > > $ qemu -qmp stdio > (qmp) load-config /some/file.yaml > > vs > > $ qemu -qmp stdio -load-config /some/file.yaml > > though the latter is probably slightly nicer as it lets you grep > for the VM based on the filename visible in the CLI.
Once QEMU can do the former, providing the latter should be trivial. Not providing it would be unadvisable. Yes, a management application that talks QMP anyway can be expected to be quite happy with having to do initial configuration via QMP, with or without a load-config command. But human users won't be happy. Having to use a wrapper program to feed their configuration file to QMP adds undue complexity. [...]
