On Mon, Jul 27, 2009 at 07:44:27PM +0100, Daniel P. Berrange wrote: > On Mon, Jul 27, 2009 at 03:38:57PM -0300, Glauber Costa wrote: > > On Mon, Jul 27, 2009 at 07:28:17PM +0100, Daniel P. Berrange wrote: > > > On Mon, Jul 27, 2009 at 03:20:08PM -0300, Glauber Costa wrote: > > > > On Mon, Jul 27, 2009 at 08:10:24PM +0200, Jan Kiszka wrote: > > > > > > > > > > I think we should simply resolves this the way upstream does: Do not > > > > > start if modules are missing and -no-kvm is omitted - or even switch > > > > > over to -enable-kvm as I think you already suggested in some other > > > > > thread. Then we can either fail or succeed, but not fall back more or > > > > > less silently. This falling back of qemu-kvm to tcg is a constant source > > > > > of confusion anyway. > > > > > > > > switching to --enable-kvm would be my preferred solution, but guys from > > > > mgmt tools may not like it. > > > > > > Totally agree that it should never ever fallback to a different mode than > > > the one requested, since falling back from KVM to QEMU simply means the > > > user doesn't discover the problem till their VM install has wasted an > > > hour of their time. Personally I would vote for --accelmode qemu|kvm|kqemu > > > since it is more future proof, but I'm not too bothered if people prefer > > > to have --enable-kvm on the grounds that kqemu is being killed off. > > > libvirt just needs a reliable way to request one of qemu, kvm, or kqemu, > > > and either get an error message, or have the requested mode work. > > The big problem here is that in qemu-kvm.git, kvm happens without any user request. > > That would be the advantage of --enable-kvm or --accelmode, or whatever. > > Simply changing the default to kill the VM if we fail to initialize KVM is cumbersome, > > because it would mean that users of pure tcg would have to add an option for a > > basic VM to work. > > Well, we could go for logic like: > > * No arg given => try kvm, try kqemu, try tcg > * --accelmode arg given => try $arg, and fail if unavailable > > then libvirt would simply always supply --accelmode for all VMs, > while people running qemu manually would get best available were best available can mean a crash. If we're getting this sort of things now, that we're in fall back mode, and thus testing it once in a while, imagine when most of us don't even bother. The only sane semantics to me is: * No arg given => tcg. * some arg given: try it, and if we fail, exit. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
