13 March 2023
A Working Serial Console in KVM Guests
Topics:
Linux
Tags:
kvm
You can't login to your kvm guest via ssh, and you want to connect with virsh console. Then nothing happens.
By default guests don’t have a working console.
You’ll need to edit the guest with virsh edit to make sure it has the needed entries:
<console type='pty'>
<target type='virtio' port='0'/>
</console>
<controller type='virtio-serial' index='0'>
<address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/>
</controller>
and need to add these lines to /etc/default/grub.
GRUB\_CMDLINE\_LINUX\_DEFAULT="console=ttyS0,115200n8 console=tty1"
GRUB\_TERMINAL="serial console"
GRUB\_SERIAL\_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"
then run the command:
(redhat) grub2-mkconfig -o /boot/grub2/grub.cfg
(debian) update-grub
If you create your guests with virt-install, then adding the flag will create the console entry:
--console pty,target_type=virtio
This works for me on redhat derivitives, but not on debian, so I have more to figure out.