# Where is the man page of syscall _umtx_op?



## Yue Chen (Aug 15, 2015)

I need to do some work in the syscall level for _umtx_op. However, I cannot find a man page or other materials about this system call. It is about the userspace pthread locking.

Any idea about where can I find any documentation?


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## Nojja (Aug 15, 2015)

There's no man page for _umtx_op,
but here's the source : http://fxr.watson.org/fxr/source/kern/kern_umtx.c?v=FREEBSD60#L720
Hope it helps.


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