Multiple X logins

Chris Tyler chris at
Wed Mar 8 14:58:33 UTC 2006

On Tue, 2006-03-07 at 23:44 -0500, fedora-test-list-request at
> Though recently, it seems that certain people
> are thinking about how to solve the problems associated with multiple
> concurrent "console" user policy via dbus.  Its a long blog post and
> it will confuse you, as it continues to confuse me, until you are
> comfortable in dbus messaging syntax.

I'm concerned that we're thinking too small here. There's more to this
that multiple users on the console VTs...

- multiseat systems (several video cards/keyboards/monitors on one box -
we're seeing more of this now that we have X11R7)
- VNC and NX remote users
- housewide multimedia systems

Each of these are entangled with the console ownership issues. For

- in a multiseat system, different parts of the local hardware may be in
use by users in the different seats. Any of the users might want to use
the disc burner or mount a CD. The user on X0 may be using /dev/snd/*C1*
while the user on X1 may be using /dev/snd/*C2* and the user on X2 may
be using /dev/snd/*C0*. And I won't even get into flash drives :-O

- in a housewide multimedia system, perhaps the console user should only
get ownership of /dev/snd/*C0* while /dev/snd/*C[1-9]* remain owned by
the whole-home multimedia app, which uses them to pipe sound into other

- LTSP and NX users may want sound to be redirected through some virtual
sound device to their remote system. The ownership of that virtual
device will follow different rules than the ownership of the console

We need a table of which hardware is associated which which user ID and
which X display (whether local or remote) and a way of expressing rules
of arbitrary complexity for how the table entries are to be updated.
This table should be used not only to set ownership and permissions, but
also to enable applications to use the right device, e.g., send sound to
the correct sound card, display an icon for a new flash drive on the
right desktop, open a DVD player app on the right screen when a disc is

Chris Tyler

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