Comment 48 for bug 976124

> If I try to change user on second seat when first seat user is
> already loged in,

How were you able to get a user logged in to both seats? I thought
that the password prompt issue only made it possible for one user to
be logged in at a time. Are you doing auto-login?

> second seat turns black and has black cross instead of standard
> mouse pointer.

With X, user switching is only supported on the main seat (seat0).
LightDM currently doesn't ask logind if the current seat supports user
switching; it just assumes that it does. So trying to switch users on
the second seat will do weird things.

Ideally you wouldn't even see the menu option to switch to another
user if you're not logged in on seat0. I have a patch that partly
fixes this, but breaks other things. I'll finish it up after basic
multiseat support has been merged to LightDM.

> *) 'udevadmin info --export-db' showed only one record with
> 'master-of-seat' tag. So I added line 'TAG=="seat",
> DEVPATH=="/devices/pci0000:00/0000:00:1c.0/0000:02:00.0/*",
> TAG+="master-of-seat"' back to 99-multiseat.rules. Now udevadm shows
> two records with 'master-of-seat' tag and loginctl lists both seats.

Did this improve anything? (other than listing both seats)

> *) What is uncommon setup and what is common setup? I have two user
> accounts on my saucy install. Both requires password to login.

The default setup is the common setup. It becomes uncommon the
instant you add or remove a PAM module. There are PAM modules to do
all sorts of stuff related to user authentication. For example, there
are PAM modules to lock out users if they fail to enter their password
more than X times in a row, PAM modules to require new passwords to
match certain rules (e.g., not a variant of a dictionary word, more
than X characters long), PAM modules to require two-factor
authentication (e.g.,
<https://code.google.com/p/google-authenticator/>), etc.

It may help to post the relevant PAM config files:
   * /etc/pam.conf
   * /etc/pam.d/lightdm*
   * /etc/pam.d/common-*
   * /etc/pam.d/other

I can then compare them to my PAM config files to see if there's any
difference.