Christoph Berg <myon@debian.org> writes:
> Another data point that's admittedly much more of a footnote than
> serious input to the original question is the following: Debian has a
> (so far mostly toy) port "hurd-i386" which is using the GNU hurd
> kernel along with the usual GNU userland that's also in use on Linux.
> This OS doesn't implement any semaphores yet (PG compiles, but initdb
> dies with ENOSYS immediately). On talking to the porters, they advised
> that POSIX semaphores would have the best chances to get implemented
> first, so I added USE_UNNAMED_POSIX_SEMAPHORES=1 to the architecture
> template to be prepared for that.
As of HEAD, that should happen automatically for anything using the
"linux" template.
I did some googling (but no actual testing) to try to find out the state
of POSIX sema support for the other platform templates:
aix
AIX doesn't seem to have support (reportedly, the functions exist but
always fail).
cygwin
Not clear whether unnamed semas work on this; I found conflicting reports.
darwin
Unnamed semas are known not to work here.
hpux
Reportedly, unnamed POSIX sema support exists on HPUX 11.x, but on 10.x
sem_init fails with ENOSYS. We'd need a run-time test in configure to
see whether to use it. Doubt it's worth the trouble.
netbsd
No support for cross-process unnamed semas.
openbsd
No support for cross-process unnamed semas.
sco
Doubt anyone cares.
solaris
Apparently supported in newer versions of Solaris; as with HPUX,
we might need a run-time configure probe to tell. Again, without
specific evidence that it might be worth switching, I doubt it's
worth taking any trouble over.
unixware
Doubt anyone cares.
win32
No support.
So at this point it seems likely that stopping with Linux and FreeBSD
is the thing to do, and as far as I can tell the code we have now is
working with all variants of those that we have in the buildfarm.
(I'm a little suspicious that older variants of FreeBSD might not
have working sem_init, like the other *BSD variants, necessitating
a run-time test there. But we'll cross that bridge when we come
to it.)
So, barring further input, this project is done. I'll go update
the user docs to explain the new state of affairs.
regards, tom lane
