[libvirt] libvirt can't get capablities

Hi, I have suffered several times on both x86 machine and power machine. When we want to use libvirt to create on VMs, it reports "unknown OS type hvm". We can't get <guest> capabilities. The log is as the following(log_level=1): 2003-01-02 01:21:39.895+0000: 12214: error : virDomainDefParseXML:8491 : unknown OS type hvm 2003-01-02 01:21:39.896+0000: 12214: error : virDomainDefParseXML:8491 : unknown OS type hvm 2003-01-02 01:22:00.135+0000: 12207: error : qemuCapsComputeCmdFlags:1218 : unsupported configuration: this qemu binary requires libvirt to be compiled with yajl 2003-01-02 01:22:13.342+0000: 12207: error : qemuCapsComputeCmdFlags:1218 : unsupported configuration: this qemu binary requires libvirt to be compiled with yajl 2003-01-02 01:22:13.347+0000: 12204: error : qemuCapsExtractVersion:1576 : internal error Cannot find suitable emulator for ppc64 2003-01-02 01:22:13.351+0000: 12205: error : qemuCapsExtractVersion:1576 : internal error Cannot find suitable emulator for ppc64 2003-01-02 01:22:13.355+0000: 12207: error : qemuCapsExtractVersion:1576 : internal error Cannot find suitable emulator for ppc64 2003-01-02 01:22:13.355+0000: 12208: error : qemuCapsExtractVersion:1576 : internal error Cannot find suitable emulator for ppc64 2003-01-02 01:22:13.357+0000: 12206: error : qemuCapsExtractVersion:1576 : internal error Cannot find suitable emulator for ppc64 I search online and find one similar issue from Redhat bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=509337 Is there any solution to avoid this problem? Any idea? -- Best Regards Li IBM LTC, China System&Technology Lab, Beijing