The vm host shows this:

# setserial -g /dev/ttyS* /dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4 /dev/ttyS1, UART: 16950/954, Port: 0xd040, IRQ: 17 /dev/ttyS2, UART: 16950/954, Port: 0xd048, IRQ: 17 /dev/ttyS3, UART: 16950/954, Port: 0xd050, IRQ: 17 # # ll /dev/ttyS* crw-rw----. 1 root dialout 4, 64 Nov 10 12:18 /dev/ttyS0 crw-rw----. 1 root dialout 4, 65 Nov 10 12:18 /dev/ttyS1 crw-rw----. 1 root dialout 4, 66 Nov 10 12:18 /dev/ttyS2 crw-rw----. 1 root dialout 4, 67 Nov 10 12:18 /dev/ttyS3

By default serial 0 o guests is assigned to pty and has a device path of '-'. I have installed on the host a 4-port serial card, as evidenced above. When I add the first additional port to the guest (serial 1) and use '/dev/ttyS1' as the path the guest will boot. However, if I add a second serial port (serial 2) using path '/dev/ttyS2' then I get this error and the guest will not start:

Traceback (most recent call last): File "/usr/share/virt-manager/virtManager/engine.py", line 878, in run_domain vm.startup() File "/usr/share/virt-manager/virtManager/domain.py", line 1313, in startup self._backend.create() File "/usr/lib64/python2.6/site-packages/libvirt.py", line 333, in create if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self) libvirtError: internal error Process exited while reading console log output: char device redirected to /dev/pts/1 isa irq 4 already assigned

How does one configure additional serial ports on a kvm guest?