Added a rendez-vous variable parameter to smp_trap_non_boot_cpus() and make

boot CPU wait until all other CPUs are ready to wait. This solves a
theoretical problem in main(): The boot CPU could run fully through the early
initialization and reset sCpuRendezvous2 before the other CPUs left
smp_cpu_rendezvous(). It's very unlikely on real hardware that the non-boot
CPUs are so much slower, but it might be a concern in emulation.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@36558 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/smp.h

@@ -44,7 +44,7 @@ extern "C" {
 status_t smp_init(struct kernel_args *args);
 status_t smp_per_cpu_init(struct kernel_args *args, int32 cpu);
 status_t smp_init_post_generic_syscalls(void);
-bool smp_trap_non_boot_cpus(int32 cpu);
+bool smp_trap_non_boot_cpus(int32 cpu, uint32* rendezVous);
 void smp_wake_up_non_boot_cpus(void);
 void smp_cpu_rendezvous(volatile uint32 *var, int current_cpu);
 void smp_send_ici(int32 targetCPU, int32 message, uint32 data, uint32 data2, uint32 data3,

src/system/kernel/main.cpp

@@ -67,6 +67,7 @@ bool gKernelStartup = true;
 static kernel_args sKernelArgs;
 static uint32 sCpuRendezvous;
 static uint32 sCpuRendezvous2;
+static uint32 sCpuRendezvous3;
 
 static int32 main2(void *);
 
@@ -100,7 +101,7 @@ _start(kernel_args *bootKernelArgs, int currentCPU)
 	thread_preboot_init_percpu(&sKernelArgs, currentCPU);
 
 	// if we're not a boot cpu, spin here until someone wakes us up
-	if (smp_trap_non_boot_cpus(currentCPU)) {
+	if (smp_trap_non_boot_cpus(currentCPU, &sCpuRendezvous3)) {
 		// init platform
 		arch_platform_init(&sKernelArgs);
 

src/system/kernel/smp.cpp

@@ -1044,20 +1044,25 @@ smp_send_broadcast_ici_interrupts_disabled(int32 currentCPU, int32 message,
 }
 
 
+/*!	Spin on non-boot CPUs until smp_wake_up_non_boot_cpus() has been called.
+
+	\param cpu The index of the calling CPU.
+	\param rendezVous A rendez-vous variable to make sure that the boot CPU
+		does not return before all other CPUs have started waiting.
+	\return \c true on the boot CPU, \c false otherwise.
+*/
 bool
-smp_trap_non_boot_cpus(int32 cpu)
+smp_trap_non_boot_cpus(int32 cpu, uint32* rendezVous)
 {
-	if (cpu > 0) {
-#if B_DEBUG_SPINLOCK_CONTENTION
-		boot_cpu_spin[cpu].lock = 1;
-#else
-		boot_cpu_spin[cpu] = 1;
-#endif
-		acquire_spinlock_nocheck(&boot_cpu_spin[cpu]);
-		return false;
+	if (cpu == 0) {
+		smp_cpu_rendezvous(rendezVous, cpu);
+		return true;
 	}
 
-	return true;
+	acquire_spinlock_nocheck(&boot_cpu_spin[cpu]);
+	smp_cpu_rendezvous(rendezVous, cpu);
+	acquire_spinlock_nocheck(&boot_cpu_spin[cpu]);
+	return false;
 }