Ian,
It seems that go-go.c needs to be more portable. This issue apparently was
addressed in gcc/boehm-gc/pthread_stop_world.c with...
/*
* We use signals to stop threads during GC.
*
* Suspended threads wait in signal handler for SIG_THR_RESTART.
* That's more portable than semaphores or condition variables.
* (We do use sem_post from a signal handler, but that should be portable.)
*
* The thread suspension signal SIG_SUSPEND is now defined in gc_priv.h.
* Note that we can't just stop a thread; we need it to save its stack
* pointer(s) and acknowledge.
*/
#ifndef SIG_THR_RESTART
# if defined(GC_HPUX_THREADS) || defined(GC_OSF1_THREADS)
# ifdef _SIGRTMIN
# define SIG_THR_RESTART _SIGRTMIN + 5
# else
# define SIG_THR_RESTART SIGRTMIN + 5
# endif
# else
# define SIG_THR_RESTART SIGXCPU
# endif
#endif
Jack