Philippe Gerum authored Oct 14, 2018 and Jan Kiszka committed Oct 17, 2018

The CPU affinity mask in __base_setup_data.cpu_affinity - which may be
set by --cpu-affinity - is conventionally checked by applications for
determining which CPUs are usable for real-time duties.

Over Cobalt, we need to make sure that such mask reflects the set of
CPUs available for running real-time threads as defined by the core
(i.e. /proc/xenomai/affinity), in absence of --cpu-affinity
setting.

Otherwise, some applications like switchest looking at an empty
affinity mask may wrongly assume that all CPUs are available for
running RT threads, leading to a failure when manually pinning such
thread to an invalid (non-RT) CPU.

With current Cobalt core and I-pipe releases not fixed for gracefully
handling invalid domain migration requests over a non-RT CPU, such a
failure may trigger a kernel panic.

Signed-off-by: Philippe Gerum <rpm@xenomai.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>