On a prototype DomU system (an X4200 server) an issue was discovered where console access to the domains from the hypervisor system via the "virsh console" command does not function as one would expect.
In particular when using the command "virsh console <domain name>" from a hypervisor login multiple console sessions can be started from different login shells and all of them have read/write access to the same serial console of a given configured DomU domain.
Among the effects of this are:
* Standard input for the virtual serial console command is not attached to any particular virtual console so that both console commands can write to the same shell/console login prompt.
* Standard output is not attached to any particular virtual serial console and output can appear on either (or possibly any, configurations of more than two console logins have not been tested) of the "virsh console" sessions.
* Output or input can be dumped (typed commands will not always be fully echoed on either virtual serial console)
* Output (either the echoing of typed commands or command output) can appear in another virtual console session to the one where input is being sent to (there is not "temporary locking" as it were).
The manual page for the virsh command does not suggest that the virsh "console" subcommand has an option to enforce console access exclusivity
The virsh version being used is:
virsh # version
Compiled against library: libvir 0.2.3
Using library: libvir 0.2.3
Using API: Xen 3.0.1
Running hypervisor: Xen 3.0
See 6548707 multiple invocations of xm console to the same domU results in multiple instances of broken consoles