Re: cmpxchg in 2.5.38

[David S. Miller]

   From: Pete Zaitcev <[e-mail]>
   Date: Wed, 25 Sep 2002 01:00:44 -0400

   The cmpxchg() is used in kernel/pid.c:next_free_map():
   
                           if (cmpxchg(&map->page, NULL, (void *) page))
                                   free_page(page);
   
   It is implemented on alpha, i386, ia64, ppc64, ppc, sparc64,
   x86_64, but not on mips, cris, arm, s390, s390x, sparc, sh, parisc.
   Do all architectures have to have it?
   
Indeed, we can't really make cmpxchg a requirement, many
cpus lack it.