[Libguestfs] cannot start domain with channel device

　Here is what I get.root@ubuntu:/home/john# virsh start ubuntu2error: Failed to start domain ubuntu2error: internal error Process exited while reading console log output: char device redirected to /dev/pts/1bind(unix:/var/lib/libvirt/qemu/ubuntu2.libguestfs): Permission deniedchardev: opening backend "socket" failed: Permission denied 　root@ubuntu:/home/john# ll /var/lib/libvirt/qemu/total 20drwxr-x--- 5 libvirt-qemu kvm  4096 Jul  5 14:44 ./drwxr-xr-x 8 root         root 4096 May 20 04:18 ../drwxr-xr-x 2 libvirt-qemu kvm  4096 May 20 04:18 dump/drwxr-xr-x 2 libvirt-qemu kvm  4096 May 20 04:18 save/drwxr-xr-x 2 libvirt-qemu kvm  4096 May 20 04:18 snapshot/ root@ubuntu:/home/john# cat /etc/libvirt/qemu/ubuntu2.xml<!--WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BEOVERWRITTEN AND LOST. Changes to this xml configuration should be made using:  virsh edit ubuntu2or other application using the libvirt API.--><domain type='kvm' xmlns:qemu='/schemas/domain/qemu/1.0'><qemu:commandline>  <qemu:arg value='-s'/></qemu:commandline>  <name>ubuntu2</name>  <uuid>03f4c36d-9509-05dd-167d-d2613d1dd883</uuid>  <memory>1024000</memory>  <currentMemory>1024000</currentMemory>  <vcpu>1</vcpu>  <os>    <type arch='x86_64' machine='pc-1.0'>hvm</type>    <boot dev='hd'/>  </os> 　<features>    <acpi/>    <apic/>    <pae/>  </features>  <clock offset='utc'/>  <on_poweroff>destroy</on_poweroff>  <on_reboot>restart</on_reboot>  <on_crash>restart</on_crash>  <devices>    <emulator>/usr/bin/kvm</emulator>    <disk type='file' device='disk'>      <driver name='qemu' type='qcow2'/>      <source file='/home/john/ubuntu-1204-vm.img'/>      <target dev='hda' bus='ide'/>      <address type='drive' controller='0' bus='0' unit='0'/>    </disk>    <controller type='ide' index='0'>      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>    </controller>    <interface type='bridge'>      <mac address='52:54:00:d4:7d:07'/>      <source bridge='br0'/>      <model type='virtio'/>      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>    </interface>    <serial type='pty'>      <target port='0'/>    </serial>    <console type='pty'>      <target type='serial' port='0'/>    </console> 　<input type='mouse' bus='ps2'/>    <graphics type='vnc' port='-1' autoport='yes'/>    <sound model='ich6'>      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>    </sound>    <video>      <model type='cirrus' vram='9216' heads='1'/>      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>    </video>    <memballoon model='virtio'>      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>    </memballoon><channel type='unix'>  <source mode='bind' path='/var/lib/libvirt/qemu/ubuntu2.libguestfs' />  <target type='virtio' name='org.libguestfs.channel.0' /></channel>  </devices></domain> When I deleted the <channel>...</channel> part, it will start normally. But I need it to use guestfish with --live option.