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Date: Sun, 26 Jun 2005 23:19:58 -0500
From: Dan Nelson <dnelson@allantgroup.com>
To: Pablo Mora <fbsd.hackers@gmail.com>
Message-ID: <20050627041958.GB51206@dan.emsphone.com>
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Cc: freebsd-hackers@freebsd.org
Subject: Re: problem handling POSIX thread on FreeBSD
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In the last episode (Jun 26), Pablo Mora said:
> int main() {
> ....
>     if(pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM) != 0)
>      /* handler */
> ....
> }
> 
> $ gcc taller.c -pthread
> $ ./a.out
> pthread_attr_setscope: Unknown error: 0
> $
> 
> PTHREAD_SCOPE_SYSTEM fail on freebsd ?

The libc_r and libthr threads libraries do not support
PTHREAD_SCOPE_SYSTEM.  The standard does not require support for both
PTHREAD_SCOPE_PROCESS and PTHREAD_SCOPE_SYSTEM, so it's better if you
don't treat failure of pthread_attr_setscope() as fatal to the program. 
If you're running FreeBSD 4.0, your only choice of threads library is
libc_r.

Also note that the pthread_attr_*() functions are special in that they
do not set the errno variable.  They return their error code, so you
need to do something like:

  rv = pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);
  if (rv && rv != ENOTSUP)
    handle_error();

-- 
	Dan Nelson
	dnelson@allantgroup.com