[libvirt] [RFC] Per machine type qemu capability detection

Hi, qemu recently added a qmp/hmp command ("get-cpu-max") to determine maximum number of supported CPUs for a VM. The output of this command depends on the machine type that is used when it is called. The problem here is that libvirt uses "-M none" while detecting capabilities and with that machine type the get-cpu-max command returns always 1. My question is: Is it worthwhile to do per machine type capability detection? It definitely isn't worth doing just for the get-cpu-max support, but it might be needed for Q35 or other stuff that may depend on the actual machine type used. Pros of this approach: ---------------------- - (possibly) more accurate capabilities Cons: ----- - ~10x more qemus started on libvirtd startup (one per machine type) Thanks for your opinions. Peter