5.1. 커널 시작

/*
 *	Activate the first processor.
 */

asmlinkage void __init start_kernel(void)
{
	char * command_line;
	unsigned long mempages;
	extern char saved_command_line[];
/*
 * Interrupts are still disabled. Do necessary setups, then
 * enable them
 */
(1)
	lock_kernel();
(2)
	printk(linux_banner);
(3)
	setup_arch(&command_line);
(4)
	printk("Kernel command line: %s\n", saved_command_line);
(5)
	parse_options(command_line);
(6)
	trap_init();
(7)
	init_IRQ();
(8)
	sched_init();
(9)
	softirq_init();
(10)
	time_init();

	/*
	 * 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.
	 */
(11)
	console_init();
#ifdef CONFIG_MODULES
(12)
	init_modules();
#endif
	if (prof_shift) {
		unsigned int size;
		/* only text is profiled */
		prof_len = (unsigned long) &_etext - (unsigned long) &_stext;
		prof_len >>= prof_shift;
		
		size = prof_len * sizeof(unsigned int) + PAGE_SIZE-1;
		prof_buffer = (unsigned int *) alloc_bootmem(size);
	}

(13)
	kmem_cache_init();
(14)
	sti();
(15)
	calibrate_delay();
#ifdef CONFIG_BLK_DEV_INITRD
	if (initrd_start && !initrd_below_start_ok && 
			initrd_start < min_low_pfn << PAGE_SHIFT) {
		printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
		    "disabling it.\n",initrd_start,min_low_pfn << PAGE_SHIFT);
		initrd_start = 0;
	}
#endif
(16)
	mem_init();
(17)
	kmem_cache_sizes_init();
	pgtable_cache_init();

	mempages = num_physpages;

(18)
	fork_init(mempages);
(19)
	proc_caches_init();
(20)
	vfs_caches_init(mempages);
	buffer_init(mempages);
	page_cache_init(mempages);
#if defined(CONFIG_ARCH_S390)
	ccwcache_init();
#endif
	signals_init();
#ifdef CONFIG_PROC_FS
	proc_root_init();
#endif
#if defined(CONFIG_SYSVIPC)
(21)
	ipc_init();
#endif
(22)
	check_bugs();
	printk("POSIX conformance testing by UNIFIX\n");

	/* 
	 *	We count on the initial thread going ok 
	 *	Like idlers init is an unlocked kernel thread, which will
	 *	make syscalls (and thus be locked).
	 */
(23)
	smp_init();
(24)
	rest_init();
}