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Date: Wed, 23 Dec 2009 09:49:53 +0800
From: David Xu <davidxu@freebsd.org>
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Subject: first patch for process-shared semaphore 
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This is my first attempt to make process-shared mutex work, this means
you can mmap(MAP_SHARED) a memory area, and put semaphore there,
or you can sem_open a named semaphore, and just use it between
processes, the named semaphore uses file system and mmap(), directory 
/tmp/.semaphore is used as IPC directory, any named semaphore
locates in the directory. old semaphore implementation still exists
to make it binary compatible, it uses symbol version.

http://people.freebsd.org/~davidxu/patch/shared_semaphore_1.patch


David Xu