Linux Bootup secquence

Kernel 入口点
连接脚本：arch/arm64/kernel/vmlinux.lds.S
入口 arch/arm64/kernel/entry.S

start_kernel

• setup_arch
  • setup_processor
  • setup_machine_fdt
  • early_fixmap_init
  • early_ioremap_init
  • parse_early_param
  • local_async_enable
  • efi_init
  • arm64_memblock_init
  • smp_build_mpidr_hash
  • vfs_cache_init
• rest_init
  • 初始化多线程环境
  • start kernel_init (先跑initcall， 然后init进程)
  • start kthreadd (启动内核线程)
  • waitfor kthreadd
  • 启动smp环境，进行cpu idle调度 （idle/ swapper）

kernel_init
- kernel_init_freeable
- wait for kthread_done
- do_pre_smp_initcalls();
- lockup_detector_init();
- smp_init();
- sched_init_smp();
- do_basic_setup();
- cpuset_init_smp();
- usermodehelper_init();
- shmem_init();
- driver_init();
- /* These are the core pieces /
- devtmpfs_init();
- devices_init();
- buses_init();
- classes_init();
- firmware_init();
- hypervisor_init();
- / These are also core pieces, but must come after the
- * core core pieces.
- */
- platform_bus_init();
- cpu_dev_init();
- memory_dev_init();
- container_dev_init();
- init_irq_proc();
- do_ctors();
- usermodehelper_enable();
- do_initcalls();
- random_int_secret_init();
- Open the /dev/console on the rootfs
- exec init

kthreadd 管理内核线程，遍历链表调用create_kthread，