PVR/Contents
Tvheadend is a TV streaming server for Linux supporting DVB-S, DVB-S2, DVB-C, DVB-T, ATSC, IPTV, and Analog video (V4L) as input sources and can be used as a PVR backend of XBMC.
Tvheadend does not currently support Timeshifting or live rewind, however all other PVR functions should work without issue.
Preinstalled options
The following XBMC/OS distributions come with Tvheadend already installed, or easily installed as an option. These are great one-stop solutions that can greatly simplify the installation of the backend, as well as various other benefits unique to those distros.
Most Debian and Ubuntu installations can take advantage of the standard APT installation methods for getting Tvheadend installed, either using a GUI package manager, or from the command line using "apt-get install tvheadend".
Raspberry Pi
The easiest way to get Tvheadend on the Raspberry Pi is to use OpenELEC.