Linux start_kernel函数

asmlinkage void __init start_kernel(void){	char * command_line;	extern const struct kernel_param __start___param[], __stop___param[]; 	/*	 * Need to run as early as possible, to initialize the	 * lockdep hash:	 */	lockdep_init();/*内核调试模块，用于检查内核互斥机制潜在的死锁问题*/	smp_setup_processor_id();/* 指定当前的cpu的逻辑号，这个函数对应于对称多处理器的设置，当系统中只有一个cpu的情况，此函数为空，什么也不做 */  	debug_objects_early_init(); 	/*	 * Set up the the initial canary ASAP:	 */	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*/ 	cgroup_init_early();/*一组进程的行为控制，做数据结构和其中链表的初始化*/ 	local_irq_disable();/*关闭当前CUP中断*/	early_boot_irqs_disabled = true; /* * Interrupts are still disabled. Do necessary setups, then * enable them */	tick_init();/*初始化内核时钟系统*/	boot_cpu_init();/*激活当前CPU*/	page_address_init();/*高端内存相关，未定义的话为空函数*/	printk(KERN_NOTICE "%s", linux_banner);	setup_arch(&command_line);/*内核架构相关初始化函数*/	mm_init_owner(&init_mm, &init_task);/*初始化init_mm结构体*/	mm_init_cpumask(&init_mm);	setup_command_line(command_line);/*对command_line进行备份与保存*/	setup_nr_cpu_ids();/*以下三个函数针对SMP处理器，不是SMP处理器都为空函数*/	setup_per_cpu_areas();	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */ 	build_all_zonelists(NULL, NULL);/*设置内存相关节点和其中的内存域数据结构*/	page_alloc_init();	/*打印与解析内核启动参数*/	printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);	parse_early_param();	parse_args("Booting kernel", static_command_line, __start___param,		   __stop___param - __start___param,		   -1, -1, &unknown_bootoption); 	jump_label_init(); 	/*	 * These use large bootmem allocations and must precede	 * kmem_cache_init()	 */	setup_log_buf(0);/*使用bootmem分配一个启动信息的缓冲区*/	pidhash_init();/*使用bootmem分配并初始化PID散列表*/	vfs_caches_init_early();/*前期VFS缓存初始化*/	sort_main_extable();/*对内核异常表进行排序*/	trap_init();/*对内核陷阱异常经行初始化，ARM架构中位空函数*/	mm_init();/*初始化内核内存分配器，启动信息中的内存信息来自此函数中的mem_init函数*/ 	/*	 * 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();/*初始化调度器数据结构并创建运行队列*/	/*	 * Disable preemption - early bootup scheduling is extremely	 * fragile until we cpu_idle() for the first time.	 */	preempt_disable();/*禁用抢占和中断，早期启动时期，调度是极其脆弱的*/	if (!irqs_disabled()) {		printk(KERN_WARNING "start_kernel(): bug: interrupts were "				"enabled *very* early, fixing it\n");		local_irq_disable();	}	idr_init_cache();/*为IDR机制分配缓存*/	perf_event_init();/*CPU性能检测机制初始化*/	rcu_init();/*内核RCU机制初始化*/	radix_tree_init();/*内核radix树算法初始化*/	/* init some links before init_ISA_irqs() */	early_irq_init();/*前期外部中断描述符初始化*/	init_IRQ();/*架构相关中断初始化*/	init_timers();/*以下5个函数是软中断和内核时钟机制初始化*/	hrtimers_init();	softirq_init();	timekeeping_init();	time_init();	profile_init();/*profile子系统初始化，内核的性能调试工具*/	call_function_init();	if (!irqs_disabled())		printk(KERN_CRIT "start_kernel(): bug: interrupts were "				 "enabled early\n");	early_boot_irqs_disabled = false;	local_irq_enable();/*开启总中断*/ 	kmem_cache_init_late();/*slab分配器后期初始化*/ 	/*	 * 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();/*初始化控制台*/	if (panic_later)/*检查内核恐慌标准，如果有问题，打印信息*/		panic(panic_later, panic_param); 	lockdep_info();/*打印lockdep调试模块信息*/ 	/*	 * 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();	/*检查initrd的位置是否符合要求*/#ifdef CONFIG_BLK_DEV_INITRD	if (initrd_start && !initrd_below_start_ok &&	    page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {		printk(KERN_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();/*内存泄露检测机制的初始化*/	setup_per_cpu_pageset();/*设置每个CPU的页组并初始化*/	numa_policy_init();/*分一致性内存访问(NUMA)初始化*/	if (late_time_init)		late_time_init();	sched_clock_init();/*初始化调度时钟*/	calibrate_delay();	pidmap_init();/*PID分配映射初始化*/	anon_vma_init();#ifdef CONFIG_X86	if (efi_enabled(EFI_RUNTIME_SERVICES))		efi_enter_virtual_mode();#endif	thread_info_cache_init();	cred_init();/*任务信用系统初始化*/	fork_init(totalram_pages);/*进程创建机制初始化*/	proc_caches_init();/*进程caches初始化*/	buffer_init();/*缓存系统初始化，创建缓存头空间，并检查其大小限制*/	key_init();/*内核密钥管理系统初始化*/	security_init();/*内核安全框架初始化*/	dbg_late_init();/*内核调试系统后期初始化*/	vfs_caches_init(totalram_pages);/*虚拟文件系统缓存初始化*/	signals_init();/*信号管理系统初始化*/	/* rootfs populating might need page-writeback */	page_writeback_init();/*页回写机制初始化*/#ifdef CONFIG_PROC_FS	proc_root_init();/*proc文件系统初始化*/#endif	cgroup_init();/*control group正式初始化*/	cpuset_init();/*CPUSET初始化*/	taskstats_init_early();/*任务状态早期初始化函数，为任务获取高速缓存并初始化互斥机制*/	delayacct_init();/*任务延迟机制初始化*/ 	check_bugs(); 	acpi_early_init(); /* before LAPIC and SMP 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();}