Control: tags -1 + confirmed Control: severity -1 minor 25.07.2013 14:42, Bastian Blank wrote: > The qemu-system-x86 logs missing KVM support as warning. Nothing in > qemu, except the KVM support itself, depends on KVM available, > especially not the Xen support. Printing a warning for something that is > not broken will scare people and qemu itself should itself produce a > proper error if KVM is requested but missing.
Well. This is, while appears to be very minor, a tough topic, having the whole twisted history in mind. I don't want to remove this warning, at least for now. The problem is that historically, kvm (or qemu-kvm) never gave up, it always used tcg (emulation) as a fallback in all default configurations. And we still follow this tradition in our /usr/bin/kvm wrapper, which requests kvm like -machine accel=kvm,tcg which means it will use kvm is available, and fall back to tcg if not. qemu itself never even enabled kvm by default, you have to specify either the above (or accel=kvm) or -enable-kvm on the command line in order to turn on kvm. Even if /usr/bin/kvm, when run in non-kvm environment, do produce a warning, it is run by libvirt most of the time, where this warning goes to a logfile and isn't seen by a regular user. I have a bugreport already when users tries to get rid of the /usr/bin/kvm wrapper by using qemu-system-x86_64 directly, but the resulting VMs run very very slow (because kvm acceleration isn't enabled). Basically, these warnings aren't being read, so the more of these you mention, the better, maybe at least some of them will be noticed. Maybe we should stop marking /usr/bin/kvm as "deprecated" and instead, request only kvm acceleration in there, so that in case kvm isn't available, the thing will refuse to start, and user will _have_ to look at the logs to determine the cause. Or maybe we should require users to explicitly specify when they need kvm, with the same effect (and get rid of /usr/bin/kvm wrapper completely). But at least before that, we should print a warning during boot if kvm isn't available. You mentioned xen, maybe qemu startup script may detect xen and do nothing? Thanks, /mjt -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
