Am 07.01.2020 um 18:43 hat Christophe de Dinechin geschrieben: > > It would break backwards compatibility for "-machine accel=tcg:kvm", > > which so far meant "use TCG if compiled in, otherwise use KVM". This is > > not something I would have a problem with... except that "tcg:kvm" is > > the default if no -accel option is provided! > > What is the rationale for picking tcg over kvm? > > My guess is that when this was selected, KVM was the new fancy unstable > thing and this was deemed the safe choice. My other guess is that this was > around 1907 or so :-) My third guess is that you will probably provide me > with a much better rationale ;-)
I know I intentionally disabled KVM in the past for debugging guests because TCG allowed a few more things there (most of -d doesn't do anything with KVM, and I think the gdb stub also had some restrictions). Requiring an explicit '-accel tcg' for such cases might be reasonable enough, though. (And if we make this change and therefore break with the habit that Peter mentioned - leaving defaults unchanged - could we make more changes that better reflect a typical use case today? For example, I doubt most people can do with only 128 MB of RAM in the guest.) Kevin
