Personalities are service interfaces exposed by the Xenomai
kernel. Personalities may or may not provide a particular system call
interface to userland. However, they do allow userland processes to
bind to them via the built-in sc_nucleus_bind syscall, for attaching a
process.

Therefore, personalities are useful for exporting a complete set of
additional kernel services, and/or (solely) providing process resource
management via the ppd mechanism.

Unlike skins, personalities live in kernel space
exclusively. Therefore, they are not aimed at implementing RTOS
emulators which should live in userland, on top of the Copperplate
emulation system. Instead, Xenomai personalities implement:

- core Xenomai interfaces, such as Cobalt and RTDM.

- extensions to the Cobalt API, by mean of a RTDM driver which should
  belong to the RTDM_CLASS_COBALT class.