D-Bus functionality runs as a daemon: typically dbus-daemon. Users can run several instances of it, each called a channel. Most systems implement a privileged system channel, with a private instance for each logged-in user. The private instances are required because the system channel has access restrictions. The design of D-Bus addresses two specific cases: [...] 2. communication between the desktop session and the operating system, where the operating system would typically include the kernel and any system daemons or processes