[Libguestfs] cannot connect to channel device

[Richard W.M. Jones]

On Mon, Jul 07, 2014 at 09:23:05AM +0800, fangtuo90 wrote:
> Here is what I got.
> root at ubuntu:/home/john# virsh start ubuntu2
> error: Failed to start domain ubuntu2
> error: internal error Process exited while reading console log output: char device redirected to /dev/pts/1
> bind(unix:/var/lib/libvirt/qemu/ubuntu2.libguestfs): Permission denied
> chardev: opening backend "socket" failed: Permission denied
> 
> root at ubuntu:/home/john# ll /var/lib/libvirt/qemu/
> total 20
> drwxr-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/

I'm guessing this is some kind of permissions or SELinux labelling
problem, but I don't know specifically what the problem is.

Have a look at the libvirt configuration file /etc/libvirt/qemu.conf
to see what user qemu runs as.  Also if using SELinux or AppArmor then
look for alerts there.

You might be better off asking on the libvirt-users mailing list.

Rich.

> root at ubuntu:/home/john# cat /etc/libvirt/qemu/ubuntu2.xml
> <!--
> WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
> OVERWRITTEN AND LOST. Changes to this xml configuration should be made using:
>   virsh edit ubuntu2
> or 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.

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-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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