Re: [Valgrind-users] Need a configure check for NPTL

[Julian S. <js...@ac...>]

On Sunday 06 April 2003 6:48 pm, Robert Walsh wrote:
> > Anyone have a reliable check easily to hand?
>
> Yeugh.  I don't know if this is reliable, but pthread_tryjoin_np is
> implemented in nptl but not in the original pthread stuff.  Perhaps a
> check for that will let you know?  It will certainly let you know if
> pthread_tryjoin_np is implemented, but you might allow yourself to infer
> from that that it's nptl... :-)

Hmm.  Sounds a plausible scheme, but ...

On the one hand (on RH 9),   nm /lib/tls/libpthread.so.0 | grep tryjoin
shows pthread_tryjoin_np as an exported text symbol ("T").

On the other hand, you can't link against it:

   sewardj@localhost:~/VgHEAD/valgrind$ cat nptltest.c

   #include <pthread.h>
   extern int pthread_tryjoin_np;
   int main (int argc, char * argv )
   {
      int* p = (int*)(& pthread_tryjoin_np);
      return 0;
   }

   sewardj@localhost:~/VgHEAD/valgrind$ gcc -o nptltest nptltest.c -lpthread
   /tmp/ccWjnvw9.o(.text+0x13): In function `main':
   : undefined reference to `pthread_tryjoin_np'
   collect2: ld returned 1 exit status

Now what?  If the symbol is in the DSO, why can't I link to it?
Mystified.

J