hi all, There is a bug here https://bugzilla.redhat.com/show_bug.cgi?id=981261 about controller configuration. For the pci-bridge controller, if index less than zero, there is no alert for it, and libvirt will pass this value to qemu-kvm. But qemu-kvm will report the argument error, like: "qemu-kvm: -device pci-bridge,chassis_nr=-1,id=pci.-1,bus=pci.0,addr=0x9: Parameter 'chassis_nr' expects uint8_t" So libvirt should check the arguments of controller. Here is my patch for pci-bridge： --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -5693,6 +5693,14 @@ virDomainControllerDefParseXML(xmlNodePtr node, "have an address")); goto error; } + case VIR_DOMAIN_CONTROLLER_MODEL_PCI_BRIDGE: + if (def->idx < 0) { + virReportError(VIR_ERR_XML_ERROR, "%s", + _("pci-bridge controller index invalid, should not " + "less than zero")); + goto error; + } + } And I also see qemuBuildControllerDevStr() in qemu_command.c case VIR_DOMAIN_CONTROLLER_MODEL_PCI_BRIDGE: if (def->idx == 0) { virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", _("PCI bridge index should be > 0")); goto error; } virBufferAsprintf(&buf, "pci-bridge,chassis_nr=%d,id=pci.%d", def->idx, def->idx); And if I modify it to "def->idx > 0", testsuite will fail. So why only check "def->idx == 0" ? Thanks and regards Jincheng Miao