Re: Proposal to add a QNX 6.5 port to PostgreSQL

"Baker, Keith [OCDUS Non-J&J]" <KBaker9@its.jnj.com> writes:
> I propose that a QNX 6.5 port be introduced to PostgreSQL.

Hmm ... you're aware that there used to be a QNX port?  We removed it
back in 2006 for lack of interest and maintainers, and AFAIR you're
the first person to show any interest in reintroducing it since then.

I'm a bit concerned about reintroducing something that seems to have so
little usage, especially if the port is going to be as invasive as you
suggest:

> *         QNX lacks System V shared memory: I created "src/backend/port/posix_shmem.c" which replaces System V calls
(shmget,shmat, shmdt, ...) with POSIX calls (shm_open, mmap, munmap, shm_unlink)
 

This isn't really acceptable for production usage; if it were, we'd have
done it already.  The POSIX APIs lack any way to tell how many processes
are attached to a shmem segment, which is *necessary* functionality for
us (it's a critical part of the interlock against starting multiple
postmasters in one data directory).

> *         QNX lacks sigaction SA_RESTART: I modified "src/include/port.h" to define macros to retry system calls upon
EINTR(open,read,write,...) when compiled on QNX
 

That's pretty scary too.  For one thing, such macros would affect every
call site whether it's running with SA_RESTART or not.  Do you really
need it?  It looks to me like we just turn off HAVE_POSIX_SIGNALS if
you don't have SA_RESTART.  Maybe that code has bit-rotted by now, but
it did work at one time.
        regards, tom lane