diff --git a/include/errno.h b/include/errno.h
index d95ba2c6f..4985335ec 100644
--- a/include/errno.h
+++ b/include/errno.h
@@ -130,4 +130,6 @@ extern int errno;		  /* place where the error numbers go */
 #define EBADEPT      (_SIGN 301)  /* specified endpoint is bad */
 #define EDEADEPT     (_SIGN 302)  /* specified endpoint is not alive */
 
+#define EBADCPU		(_SIGN 1000) /* requested CPU does not work */
+
 #endif /* _ERRNO_H */
diff --git a/kernel/arch/i386/arch_smp.c b/kernel/arch/i386/arch_smp.c
index 4f1445742..1d4a59bf8 100644
--- a/kernel/arch/i386/arch_smp.c
+++ b/kernel/arch/i386/arch_smp.c
@@ -36,8 +36,8 @@ extern void * __trampoline_end;
 extern u32_t busclock[CONFIG_MAX_CPUS];
 extern int panicking;
 
-static int ap_cpu_ready;
-static int cpu_down;
+static int volatile ap_cpu_ready;
+static int volatile cpu_down;
 
 /* there can be at most 255 local APIC ids, each fits in 8 bits */
 PRIVATE unsigned char apicid2cpuid[255];
@@ -186,6 +186,11 @@ PUBLIC void smp_shutdown_aps(void)
 	for (cpu = 0; cpu < ncpus; cpu++) {
 		if (cpu == cpuid)
 			continue;
+		if (!cpu_test_flag(cpu, CPU_IS_READY)) {
+			printf("CPU %d didn't boot\n", cpu);
+			continue;
+		}
+
 		cpu_down = -1;
 		barrier();
 		apic_send_ipi(APIC_SMP_CPU_HALT_VECTOR, cpu, APIC_IPI_DEST);
diff --git a/kernel/smp.c b/kernel/smp.c
index 38d503457..2dd730491 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -27,9 +27,20 @@ SPINLOCK_DEFINE(boot_lock)
 
 PUBLIC void wait_for_APs_to_finish_booting(void)
 {
+	unsigned n = 0;
+	int i;
+
+	/* check how many cpus are actually alive */
+	for (i = 0 ; i < ncpus ; i++) {
+		if (cpu_test_flag(i, CPU_IS_READY))
+			n++;
+	}
+	if (n != ncpus)
+		printf("WARNING only %d out of %d cpus booted\n", n, ncpus);
+
 	/* we must let the other CPUs to run in kernel mode first */
 	BKL_UNLOCK();
-	while (ap_cpus_booted != (ncpus - 1))
+	while (ap_cpus_booted != (n - 1))
 		arch_pause();
 	/* now we have to take the lock again as we continu execution */
 	BKL_LOCK();
diff --git a/kernel/system.c b/kernel/system.c
index 0c79ae7a6..cf0fe9ba0 100644
--- a/kernel/system.c
+++ b/kernel/system.c
@@ -653,6 +653,8 @@ PUBLIC int sched_proc(struct proc *p,
 #ifdef CONFIG_SMP
 	if ((cpu < 0 && cpu != -1) || (cpu > 0 && (unsigned) cpu >= ncpus))
 		return(EINVAL);
+	if (cpu != -1 && !(cpu_is_ready(cpu)))
+		return EBADCPU;
 #endif
 
 	/* In some cases, we might be rescheduling a runnable process. In such
diff --git a/servers/pm/glo.h b/servers/pm/glo.h
index 76feac5c1..69631d990 100644
--- a/servers/pm/glo.h
+++ b/servers/pm/glo.h
@@ -29,5 +29,5 @@ EXTERN char monitor_code[256];
 
 EXTERN struct machine machine;		/* machine info */
 #ifdef CONFIG_SMP
-EXTERN unsigned cpu_proc[CONFIG_MAX_CPUS];
+EXTERN int cpu_proc[CONFIG_MAX_CPUS];
 #endif
diff --git a/servers/sched/schedule.c b/servers/sched/schedule.c
index e73e3ac4e..39e8986e7 100644
--- a/servers/sched/schedule.c
+++ b/servers/sched/schedule.c
@@ -38,6 +38,10 @@ FORWARD _PROTOTYPE( void balance_queues, (struct timer *tp)		);
 #define schedule_process_migrate(p)	\
 	schedule_process(p, SCHEDULE_CHANGE_CPU)
 
+#define CPU_DEAD	-1
+
+#define cpu_is_available(c)	(cpu_proc[c] >= 0)
+
 #define DEFAULT_USER_TIME_SLICE 200
 
 /* processes created by RS are sysytem processes */
@@ -62,7 +66,12 @@ PRIVATE void pick_cpu(struct schedproc * proc)
 		return;
 	}
 
+	/* if no other cpu available, try BSP */
+	cpu = machine.bsp_id;
 	for (c = 0; c < machine.processors_count; c++) {
+		/* skip dead cpus */
+		if (!cpu_is_available(c))
+			continue;
 		if (c != machine.bsp_id && cpu_load > cpu_proc[c]) {
 			cpu_load = cpu_proc[c];
 			cpu = c;
@@ -218,7 +227,13 @@ PUBLIC int do_start_scheduling(message *m_ptr)
 
 	/* Schedule the process, giving it some quantum */
 	pick_cpu(rmp);
-	if ((rv = schedule_process(rmp, SCHEDULE_CHANGE_ALL)) != OK) {
+	while ((rv = schedule_process(rmp, SCHEDULE_CHANGE_ALL)) == EBADCPU) {
+		/* don't try this CPU ever again */
+		cpu_proc[rmp->cpu] = CPU_DEAD;
+		pick_cpu(rmp);
+	}
+
+	if (rv != OK) {
 		printf("Sched: Error while scheduling process, kernel replied %d\n",
 			rv);
 		return rv;