hello.
I'm in the process of researching to build a powerful multiseat server.
as I use kde as a main DE, I've wanted to ask, does kde has support for multiseat?
I know it can be done using nested xserver, if I run multiple xservers, does it runs a distinct instance of kde (kdelibs and etc...) for each user or the basic is shared?

thanks.

As with all Linux systems, the libraries themselves are shared. Nothing else is shared between individual users other than the installation itself ( applications, libraries, icons, themes, etc. ). You can have as many users as the systems capabilities permit using the system, as long as they have a seperate XServer each.

Note that having a user logged in twice with the same $KDEHOME may present complications including file corruption.

thanks for the info, so it is down to xserver nesting, how does phonon handles it? (multiple audio input\output)

Phonon will use the first available audio output that functions I believe. If you can find a way of uniquely identifying which seat belongs to which sound card, then you can generate the appropriate configuration file and have it copied to ~/.config/kde.org as part of the login process.