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Re: Moving pthread_(cond|mutex) to libc

On Tue, 22 Jan 2013, Emmanuel Dreyfus wrote:
Starting with NetBSD 6.0, libpthread is cursed with the NOLOAD flag, which means it cannot be loaded by dlopen(). The problem is that we can easily get to dlopen'able modules that do not use pthreads, but are linked to libraries that are linked with -lpthread. Such module cannot be loaded anymore in NetBSD 6.0.

Yes. And such modules would not work properly even if they were allowed to be loaded.

It seems there is a conensus that pthread_(cond|mutex) should move to libc so that libpthread could be freed from NOLOAD [See]. I started looking at it and of course it raises a few problems.

Please don't cite a thread from tech-pkg as consensus for anything in the base system. You could use it as the start of a discussion, but it's possible that a different conclusion will be reached.

Also, please lets get the overall design clarified before you write any code. I'd like to see a description of what would happen if a program starts without pthreads, creates and uses some condvars and mutexes, and then loads libpthread and continues using the already-created condvars and mutexes.

--apb (Alan Barrett)

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