kernel通过psci的smc让从cpu boot的过程

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已于 2025-07-10 09:08:50 修改 · 1w 阅读

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#算法

于 2017-05-22 10:46:55 首次发布

kernel会调用smp_init 来让从核cpu 起来.
void __init smp_init(void)
{
   unsigned int cpu;

   idle_threads_init();
   cpuhp_threads_init();

   /* FIXME: This should be done in userspace --RR */
   for_each_present_cpu(cpu) {
       if (num_online_cpus() >= setup_max_cpus)
           break;
       if (!cpu_online(cpu))
           cpu_up(cpu);
   }

   /* Any cleanup work */
   smp_announce();
   smp_cpus_done(setup_max_cpus);
}
在smp_init 中会通过for_each_present_cpu，让每一个present的cpu wakeup起来。其会调用cpu_up
int cpu_up(unsigned int cpu)
{
   return do_cpu_up(cpu, CPUHP_ONLINE);
}

继续调用do_cpu_up，这里传递的参数是CPUHP_ONLINE
static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
{
   int err = 0;

   if (!cpu_possible(cpu)) {
       pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
               cpu);
#if defined(CONFIG_IA64)
       pr_err("please check additional_cpus= boot parameter\n");
#endif
       return -EINVAL;
   }

   err = try_online_node(cpu_to_node(cpu));
   if (err)
       return err;

   cpu_maps_update_begin();

   if (cpu_hotplug_disabled) {
       err = -EBUSY;
       goto out;
   }

   err = _cpu_up(cpu, 0, target);
out:
   cpu_maps_update_done();
   return err;
}
在do_cpu_up 中的target就是CPUHP_ONLINE，继续调用_cpu_up
static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
{
   struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cp