What does the -pthread do?

What does the -pthread do?

[Claudius Link]

Hello,

I am quite confused at the moment. I just found the -pthread option for gcc
mentioned on the blitz++ (a numerical library at
		http://www.oonumerics.org/blitz/manual/blitz08.html#l118)
home page and tried to check what it actually did.

But only very unsuccessful.
For gcc 3.0.3 and 2.95.4 there is only a  -mthreads option for IBM RS/6000 
mentioned in the manual. 
But both gcc versions seem to accepted -pthread.

To get me even more confused everything changes in the current development
version of the gcc manual.
The i386 options list now contains '-mthreads' and RS/6000 get '-pthread'.

The only difference I could notice was that _REENTRANT was defined.

Are there more differences?
An what is the right way to compile and link an threaded program (preferable
now an in future :-) with gcc?

Regards,
Claudius

BTW: I am not on the list so it would be nice to CC replys to me as well. I

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Re: What does the -pthread do?

[David Edelsohn]

	-pthread compiles and links a program using Posix threads.
GNU/Linux uses the -pthread option.  Solaris' native compiler uses the
-pthreads option, so GCC uses that option as well.

	-mthreads for AIX was inherited from Lynx OS.  Because most GCC
configurations use -pthread, GNU/Linux uses -pthread and -pthread makes
the type of thread library more obvious, with GCC 3.0 AIX changed to use
-pthread.

	The -pthread commandline option changes the behavior of system
header files, links the application with GCC libraries builts for Posix
threads, and links with Posix thread support in system libraries.

David