+@item
+This function does nothing and always returns 0 in programs that are not
+linked with @code{-lpthread} on some platforms:
+FreeBSD 6.4, HP-UX 11.31, Solaris 9.
+@item
+When it fails, this functions returns -1 instead of the error number on
+some platforms:
+Cygwin 1.7.5.
+@item
+This function does not immediately raise signals that were pending before
+the call and unblocked by the call on some platforms:
+IRIX 6.5.