We're hitting an assert whenever we try to create an HVM instance under Xen via libvirtd. System is running on Gentoo, package information as follows: app-emulation/xen-4.5.0 USE="api debug flask hvm pam pygrub python qemu screen" app-emulation/xen-tools-4.5.0 USE="api debug flask hvm pam pygrub python qemu screen" app-emulation/libvirt-1.2.11-r2:0/1.2.11 USE="caps libvirtd lvm macvtap nls qemu udev vepa virtualbox xen" The following commands are run in parallel: vmmachine ~ # libvirtd --listen 2015-01-22 16:33:13.596+0000: 2620: info : libvirt version: 1.2.11 2015-01-22 16:33:13.596+0000: 2620: error : udevGetDMIData:1607 : Failed to get udev device for syspath '/sys/devices/virtual/dmi/id' or '/sys/class/dmi/id' libvirtd: libxl_fork.c:350: sigchld_installhandler_core: Assertion `((void)"application must negotiate with libxl about SIGCHLD", !(sigchld_saved_action.sa_flags & 4) && (sigchld_saved_action.__sigaction_handler.sa_handler == ((__sighandler_t) 0) || sigchld_saved_action.__sigaction_handler.sa_handler == ((__sighandler_t) 1)))' failed. Aborted vmmachine ~ # VIRSH_DEBUG=0 virsh create xml create: file(optdata): xml libvirt: XML-RPC error : End of file while reading data: Input/output error error: Failed to create domain from xml error: End of file while reading data: Input/output error libvirt: Domain Config error : Requested operation is not valid: A different callback was requested