Editing X.Org Server (section)

===Multiseat configuration===
Multi-seat refers to an assembly of a single computer with multiple "seats", allowing multiple users to sit down at the computer, log in, and use the computer at the same time independently. The computer has multiple keyboards, mice, and monitors attached to it, each "seat" having one keyboard, one mouse and one monitor assigned to it. A "seat" consists of all hardware devices assigned to a specific workplace. It consists of at least one graphics device (graphics card or just an output and the attached monitor) and a keyboard and a mouse. It can also include video cameras, sound cards and more.

Due to limitation of the VT system in the Linux kernel and of the X core protocol (in particular, how X defines the relation between the root window and an output of the graphics card), multi-seat does not work out-of-the-box for the usual Linux distribution but necessitates a special configuration.

There are these methods to configure a multi-seat assembly:
* multiple [[Xephyr]] servers over a host xorg-server
* multiple instances of an xorg-server
** one graphics card per seat
** a single graphics card for all seats

The utilized command-line options of the xorg-server are:
* <code>-isolateDevice bus-id</code> Restrict device resets (output) to the device at bus-id. The bus-id string has the form bustype:bus:device:function (e.g., 'PCI:1:0:0'). At present, only isolation of PCI devices is supported; i.e., this option is ignored if bustype is anything other than 'PCI'.
* <code>vtXX</code> the default for e.g. Debian 9 Stretch is 7, i.e. by pressing {{Key|Ctrl}}+{{Key|Alt}}+{{Key|F7}} the user can switch to the VT running the xorg-server.

Only the user on the first monitor has the use of vt consoles and can use {{Key|Ctrl}}+{{Key|Alt}}+{{Key|F}}x to select them. The other users have a [[GNOME Display Manager|GDM]] login screen and can use xorg-server normally, but have no vt's.

Even though a single user can utilize multiple monitors connected to the different ports of a single graphics card (cf. RandR), the method which is based on multiple instances of the xorg-server seems to require multiple [[Conventional PCI|PCI]] graphics cards.

It is possible to configure multi-seat employing only one graphics card, but due to limitations of the X protocol this necessitates the usage of [[X Display Manager Control Protocol]] XDMCP.<ref>{{Cite web|url=https://help.ubuntu.com/community/MultiseatOneCard|title=MultiseatOneCard - Community Help Wiki|website=help.ubuntu.com}}</ref>

There is also [[Xdmx]] (Distributed Multihead X).