Hi I got a problem when using qemu 2.0.0 + libvirt 1.2.6 . It just can not define a kvm vm successfully , errors like this : # virsh define 5ab4f49c-c99f-4dbd-9d7d-17a946b4c5a7.xml error: Failed to define domain from 5ab4f49c-c99f-4dbd-9d7d-17a946b4c5a7.xml error: unknown OS type hvm after several tries, i found that Qemu2.0 /qemu-kvm1.2+ libvirt1.0.2 and lower version is ok Qemu2.0 /qemu-kvm1.2+ libvirt1.0.3 and higher version is failed I have checked system as bellows: 1 kvm,kvm_intel modules are loaded(centos 6.2 /kernel 2.6.32) 2 bios is ok for hvm 3 qemu is installed and emulator path in xml config file is correct 4 I also tried to install glusterfs-devel-3.2.7-1.el6.x86_64 and rebuild qemu , no use. so ,why Qemu2.0 /qemu-kvm1.2+ libvirt1.0.3 and above version could not work? thanks, vary much liweiwei