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