On 07/01/2020 13.54, Daniel P. Berrangé wrote: > On Tue, Jan 07, 2020 at 01:23:18PM +0100, Paolo Bonzini wrote: >> On 07/01/20 13:18, Thomas Huth wrote: >>> I don't think we need a separate priority parameter here. But IMHO it's >>> really rather common practice to prioritize the last option. So while >>> it might be more "self-explanatory" to a CLI newbie if the first >>> occurrence got the highest priority, it might be rather confusing >>> instead for a CLI veteran...? >> >> Prioritising the last certainly makes sense for a choose-one-only >> option, but I'm not sure it's the same for a choose-best option. After >> all it was -machine accel=kvm:tcg, not -machine accel=tcg:kvm... > > IIUC, the main use case for specifying multiple accelerators is > so that lazy invokations can ask for a hardware virt, but then get > fallback to TCG if not available. For things that should be platform > portabile, there's more than just kvm to consider though, as we have > many accelerators. Listing all possible accelerators is kind of > crazy though no matter what the syntax is. > > How about taking a completely different approach, inspired by the > -cpu arg and implement: > > -machine accel=best
Something like that sounds like the best solution to me, but I'd maybe rather not call it "best", since the definition of "best" might depend on your use-case (e.g. do you want to use a CPU close to the host or something different which might be better emulated by TCG?). What about "-accel any" or "-accel fastest" or something similar? Thomas
