http://blog.csdn.net/ly890700/article/details/54586484
start_kernel是内核启动后执行的第一个C语言函数，位于kernel/init/main.c中
一 start_kernel上半段
kernel/init/main.c Collapse source
| asmlinkage __visible void __init start_kernel(void)
{
char *command_line;
char *after_dashes;
/*
* Need to run as early as possible, to initialize the
* lockdep hash:
*/
lockdep_init();
set_task_stack_end_magic(&init_task);
smp_setup_processor_id();
debug_objects_early_init();
cgroup_init_early();
local_irq_disable();
early_boot_irqs_disabled = true;
/*
* Interrupts are still disabled. Do necessary setups, then
* enable them
*/
boot_cpu_init();
page_address_init();
pr_notice("%s", linux_banner);
setup_arch(&command_line);
/*
* Set up the the initial canary ASAP:
*/
boot_init_stack_canary();
mm_init_cpumask(&init_mm);
setup_command_line(command_line);
setup_nr_cpu_ids();
setup_per_cpu_areas();
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
build_all_zonelists(NULL, NULL);
page_alloc_init();
pr_notice("Kernel command line: %s\n", boot_command_line);
parse_early_param();
after_dashes = parse_args("Booting kernel",
static_command_line, __start___param,
__stop___param - __start___param,
-1, -1, &unknown_bootoption);
if (!IS_ERR_OR_NULL(after_dashes))
parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
set_init_arg);
jump_label_init();
/*
* These use large bootmem allocations and must precede
* kmem_cache_init()
*/
setup_log_buf(0);
pidhash_init();
vfs_caches_init_early();
sort_main_extable();
trap_init();
mm_init();
/*
* Set up the scheduler prior starting any interrupts (such as the
* timer interrupt). Full topology setup happens at smp_init()
* time - but meanwhile we still have a functioning scheduler.
*/
sched_init();
/*
* Disable preemption - early bootup scheduling is extremely
* fragile until we cpu_idle() for the first time.
*/
preempt_disable();
if (WARN(!irqs_disabled(),
"Interrupts were enabled *very* early, fixing it\n"))
local_irq_disable();
idr_init_cache();
rcu_init();
context_tracking_init();
radix_tree_init();
/* init some links before init_ISA_irqs() */
early_irq_init();
init_IRQ();
tick_init();
rcu_init_nohz();
init_timers();
hrtimers_init();
softirq_init();
timekeeping_init();
time_init();
sched_clock_postinit();
perf_event_init();
profile_init();
call_function_init();
WARN(!irqs_disabled(), "Interrupts were enabled early\n");
early_boot_irqs_disabled = false;
local_irq_enable();
|
在start_kernel上半段中会调用一系列初始化函数来完成内核的初始化工作：
1 lockdep_init(); 初始化内核死锁检测机制的哈希表
2 smp_setup_processor_id(); 返回cpu号，单核cpu返回0
3 debug_objects_early_init(); 对调试对象进行早期的初始化
4 local_irq_disable(); 关闭当前cpu的中断
5 boot_cpu_init(); 设置当前cpu位激活状态
6 page_address_init(); 初始化高端内存的
7 setup_arch(&command_line); 执行内核架构相关初始化函数
8 boot_init_stack_canary(); 初始化栈canary值，canary值用于防止栈溢出攻击的堆栈的保护字
9 build_all_zonelists(NULL, NULL); 建立系统内存页区(zone)链表
10 page_alloc_init(); 内存页初始化
11 在parse_args函数中解析cmdline中的启动参数
12 etup_log_buf(0); 使用memblock_alloc分配一个启动时log缓冲区
13 pidhash_init(); 初始化pid散列表
14 vfs_caches_init_early(); 初始化dentry和inode的hashtable
15 sort_main_extable(); 对内核异常向量表进行排序
16 trap_init(); 对内核陷阱异常进行初始化，arm没有用到
17 mm_init(); 初始化内核内存分配器，过度到伙伴系统，启动slab机制，初始化非连续内存区
18 sched_init(); 初始化进程调度器
19 local_irq_disable(); 关闭本地中断
20 rcu_init(); 初始化rcu机制
21 init_IRQ(); 初始化中断lockdep_init
22 tick_init(); 初始化时钟滴答控制器
23 init_timers(); 初始化内核定时器
24 softirq_init(); 初始化软中断
25 time_init(); 时钟初始化
26 profile_init(); 对内核的一个性能测试工具profile进行初始化
27 local_irq_enable(); 使能当前cpu中断
二 start_kernel下半段
kernel/init/main.c Collapse source
| kmem_cache_init_late();
/*
* HACK ALERT! This is early. We're enabling the console before
* we've done PCI setups etc, and console_init() must be aware of
* this. But we do want output early, in case something goes wrong.
*/
console_init();
if (panic_later)
panic("Too many boot %s vars at `%s'", panic_later,
panic_param);
lockdep_info();
/*
* Need to run this when irqs are enabled, because it wants
* to self-test [hard/soft]-irqs on/off lock inversion bugs
* too:
*/
locking_selftest();
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_start && !initrd_below_start_ok &&
page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
page_to_pfn(virt_to_page((void *)initrd_start)),
min_low_pfn);
initrd_start = 0;
}
#endif
page_cgroup_init();
debug_objects_mem_init();
kmemleak_init();
setup_per_cpu_pageset();
numa_policy_init();
if (late_time_init)
late_time_init();
sched_clock_init();
calibrate_delay();
pidmap_init();
anon_vma_init();
acpi_early_init();
#ifdef CONFIG_X86
if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_enter_virtual_mode();
#endif
#ifdef CONFIG_X86_ESPFIX64
/* Should be run before the first non-init thread is created */
init_espfix_bsp();
#endif
thread_info_cache_init();
cred_init();
fork_init(totalram_pages);
proc_caches_init();
buffer_init();
key_init();
security_init();
dbg_late_init();
vfs_caches_init(totalram_pages);
signals_init();
/* rootfs populating might need page-writeback */
page_writeback_init();
proc_root_init();
cgroup_init();
cpuset_init();
taskstats_init_early();
delayacct_init();
check_bugs();
acpi_subsystem_init();
sfi_init_late();
if (efi_enabled(EFI_RUNTIME_SERVICES)) {
efi_late_init();
efi_free_boot_services();
}
ftrace_init();
/* Do the rest non-__init'ed, we're now alive */
rest_init();
}
|
在下半段中主要完成：
1 kmem_cache_init_late(); 初始化slab分配器的缓存机制
2 console_init(); 初始化控制台
3 lockdep_info(); 打印锁的依赖信息
4 locking_selftest(); 死锁检测
5 page_cgroup_init(); 为page_cgroup相关结构分配存储空间
6 debug_objects_mem_init(); 创建debug_obj的slab高速缓存
7
