内核reboot流程

kernel/reboot.c

void kernel_restart(char *cmd)
{
        kernel_restart_prepare(cmd);
        migrate_to_reboot_cpu();
        syscore_shutdown();
        if (!cmd)
                pr_emerg("Restarting system\n");
        else
                pr_emerg("Restarting system with command '%s'\n", cmd);
        kmsg_dump(KMSG_DUMP_RESTART);
        machine_restart(cmd);
}

->reboot命令

->glibc给所有任务发送kill

->内核态kernel_restart()

->kernel_restart_prepare()

->device_shutdown()

-> dev->driver->shutdown() 调用驱动注册的.shutdown钩子

->migrate_to_reboot_cpu() 关闭cpu hotplug

->syscore_shutdown() 里面ops->shutdown，内核相关子系统（比如clk，irq，pm）注册的shutdown

->machine_restart

->local_irq_disable(); smp_send_stop(); /* Disable interrupts first */

-> 根据 arm_pm_restart是否初始化决定走arm_pm_restart(reboot_mode, cmd),如果是这种case，一般会写pm register将whole cpu reset；或 do_kernel_restart(cmd);

->do_kernel_restart() 执行注册的restart_handler_list

->BIOS->ATF->芯片复位

from: https://zhuanlan.zhihu.com/p/353452093