Re: [libvirt] [PATCH] Don't list capabilities entries if emulators can't be accessed

Daniel P. Berrange wrote: > On Wed, Aug 20, 2008 at 12:51:05PM -0400, Cole Robinson wrote: > >> diff --git a/src/qemu_conf.c b/src/qemu_conf.c >> index dc9e42a..0328cc1 100644 >> --- a/src/qemu_conf.c >> +++ b/src/qemu_conf.c >> @@ -230,6 +230,10 @@ qemudCapsInitGuest(virCapsPtr caps, >> virCapsGuestPtr guest; >> int i; >> >> + /* Check for existance of base emulator */ >> + if (access(info->binary, X_OK) == -1) >> + return 0; >> + > > This isn't right - this means that if KVM is installed, but QEMU is > not installed you won't get any capabilities. > > Basically we need todo all the access() checks for QEMU, KVM, /dev/kvm > up-front. And then generated the capabilites if either QEMU or KVM is > available. > Okay, I think this patch solves the issues. We check upfront for the base emulator and potential kvm emulators (qemu-kvm, and /usr/bin/kvm for ubuntu/upstream .spec). If nothing is found, just return. If only the base emulator is found, skip kvm even if /dev/kvm exists. If only kvm bin is found, add the base emulator capabilities only if emulator and host arch matches.