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POSIX.1 semaphores vs message queues
I'd like to understand the rationale that makes POSIX sempahores a
non-optional component of the kernel, while POSIX message queues are
still optional. Both seem to be related specifically to use in the
librt real-time library.
P1003_1B_SEMAPHORE option was removed about 3 1/2 years ago [1] by
Joerg, but I don't seem to see any discussion on this. And yet, we
still have MQUEUE as an option.
Yes, MQUEUE is still automatically included by default, via
src/sys/conf/std, but it can be removed by adding 'no option MQUEUE'
to a custom kernel config. There is no corresponding way to remove
the semaphore code from a kernel, since it is now included in the
kern 'package'.
Why is one optional/removeable, and the other required/mandatory? Is
there some other component within the kernel that depends heavily on
the semaphore code (I've looked, but haven't found it)?
[1] http://mail-index.netbsd.org/source-changes/2012/03/10/msg032675.html
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| Paul Goyette | PGP Key fingerprint: | E-mail addresses: |
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