Found by Laine and discussed a bit on internal IRC. Commit id c56fe7f1d6 added support for creating a command line to support scsi-disk.channel. Series was here: http://www.redhat.com/archives/libvir-list/2012-February/msg01052.html Which pointed to a design proposal here: http://permalink.gmane.org/gmane.comp.emulators.libvirt/50428 Which states (in part): Libvirt should check for the QEMU "scsi-disk.channel" property. If it is unavailable, QEMU will only support channel=lun=0 and 0<=target<=7. However, the check added was ensuring that bus != lun *and* bus != 0. So if bus == lun and both were non zero, we'd never make the second check. Changing this to an *or* check fixes the check, but still is less readable than the just checking each for 0 Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; --- src/qemu/qemu_command.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 0dc8628..583bc11 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -4127,8 +4127,8 @@ qemuBuildDriveDevStr(virDomainDefPtr def, goto error; } - if ((disk->info.addr.drive.bus != disk->info.addr.drive.unit) && - (disk->info.addr.drive.bus != 0)) { + if (disk->info.addr.drive.bus != 0 && + disk->info.addr.drive.unit != 0) { virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", _("This QEMU only supports both bus and " "unit equal to 0")); -- 2.1.0