These are all reasonably well documented in sys/conf/NOTES. If you
want more detail, try a SystemV-oriented Unix book
Close - they only control SystemV shared memory. Sane shared memory
is available via mmap(2). SystemV semaphores are controlled via
SEMxxx options. Posix semaphores are listed as 'experimental'.
Is there any chance that POSIX semaphores will be anything other than
experimental in the future, or is there no interest? Further, the man
page indicates that the FreeBSD, POSIX semaphore implementation is not
capable of supporting multiple process semaphores. I saw a similar note
on a Linux man page. I think this is a shame, since POSIX semaphores seem
to be well designed (from a user point of view) compared to SYSV
semaphores, which are a total mess.