XSI_REALTIME
The XSI_REALTIME option group indicates that the _POSIX_FSYNC,
_POSIX_MEMLOCK,
_POSIX_MEMLOCK_RANGE,
_POSIX_MESSAGE_PASSING,
_POSIX_PRIORITY_SCHEDULING,
_POSIX_SHARED_MEMORY_OBJECTS, and
_POSIX_SYNCHRONIZED_IO options are enabled.
Enable this option group with CONFIG_XSI_REALTIME.
When this option group is enabled, the _XOPEN_REALTIME feature test macro will be defined to a
value other than -1.