initial_commit

1 files changed, 835 insertions, 0 deletions

diff --git a/init/main.c b/init/main.c
new file mode 100644
index 00000000..841e344d
--- /dev/null
+++ b/init/main.c
@@ -0,0 +1,835 @@
+/*
+ *  linux/init/main.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  GK 2/5/95  -  Changed to support mounting root fs via NFS
+ *  Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
+ *  Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
+ *  Simplified starting of init:  Michael A. Griffith <grif@acm.org> 
+ */
+
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/kernel.h>
+#include <linux/syscalls.h>
+#include <linux/stackprotector.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/initrd.h>
+#include <linux/bootmem.h>
+#include <linux/acpi.h>
+#include <linux/tty.h>
+#include <linux/percpu.h>
+#include <linux/kmod.h>
+#include <linux/vmalloc.h>
+#include <linux/kernel_stat.h>
+#include <linux/start_kernel.h>
+#include <linux/security.h>
+#include <linux/smp.h>
+#include <linux/profile.h>
+#include <linux/rcupdate.h>
+#include <linux/moduleparam.h>
+#include <linux/kallsyms.h>
+#include <linux/writeback.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/cgroup.h>
+#include <linux/efi.h>
+#include <linux/tick.h>
+#include <linux/interrupt.h>
+#include <linux/taskstats_kern.h>
+#include <linux/delayacct.h>
+#include <linux/unistd.h>
+#include <linux/rmap.h>
+#include <linux/mempolicy.h>
+#include <linux/key.h>
+#include <linux/buffer_head.h>
+#include <linux/page_cgroup.h>
+#include <linux/debug_locks.h>
+#include <linux/debugobjects.h>
+#include <linux/lockdep.h>
+#include <linux/kmemleak.h>
+#include <linux/pid_namespace.h>
+#include <linux/device.h>
+#include <linux/kthread.h>
+#include <linux/sched.h>
+#include <linux/signal.h>
+#include <linux/idr.h>
+#include <linux/kgdb.h>
+#include <linux/ftrace.h>
+#include <linux/async.h>
+#include <linux/kmemcheck.h>
+#include <linux/sfi.h>
+#include <linux/shmem_fs.h>
+#include <linux/slab.h>
+#include <linux/perf_event.h>
+
+#include <asm/io.h>
+#include <asm/bugs.h>
+#include <asm/setup.h>
+#include <asm/sections.h>
+#include <asm/cacheflush.h>
+
+#ifdef CONFIG_X86_LOCAL_APIC
+#include <asm/smp.h>
+#endif
+
+static int kernel_init(void *);
+
+extern void init_IRQ(void);
+extern void fork_init(unsigned long);
+extern void mca_init(void);
+extern void sbus_init(void);
+extern void prio_tree_init(void);
+extern void radix_tree_init(void);
+extern void free_initmem(void);
+#ifndef CONFIG_DEBUG_RODATA
+static inline void mark_rodata_ro(void) { }
+#endif
+
+#ifdef CONFIG_TC
+extern void tc_init(void);
+#endif
+
+/*
+ * Debug helper: via this flag we know that we are in 'early bootup code'
+ * where only the boot processor is running with IRQ disabled.  This means
+ * two things - IRQ must not be enabled before the flag is cleared and some
+ * operations which are not allowed with IRQ disabled are allowed while the
+ * flag is set.
+ */
+bool early_boot_irqs_disabled __read_mostly;
+
+enum system_states system_state __read_mostly;
+EXPORT_SYMBOL(system_state);
+
+/*
+ * Boot command-line arguments
+ */
+#define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
+#define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
+
+extern void time_init(void);
+/* Default late time init is NULL. archs can override this later. */
+void (*__initdata late_time_init)(void);
+extern void softirq_init(void);
+
+/* Untouched command line saved by arch-specific code. */
+char __initdata boot_command_line[COMMAND_LINE_SIZE];
+/* Untouched saved command line (eg. for /proc) */
+char *saved_command_line;
+/* Command line for parameter parsing */
+static char *static_command_line;
+
+static char *execute_command;
+static char *ramdisk_execute_command;
+
+/*
+ * If set, this is an indication to the drivers that reset the underlying
+ * device before going ahead with the initialization otherwise driver might
+ * rely on the BIOS and skip the reset operation.
+ *
+ * This is useful if kernel is booting in an unreliable environment.
+ * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
+ * skipped and devices will be in unknown state.
+ */
+unsigned int reset_devices;
+EXPORT_SYMBOL(reset_devices);
+
+static int __init set_reset_devices(char *str)
+{
+	reset_devices = 1;
+	return 1;
+}
+
+__setup("reset_devices", set_reset_devices);
+
+static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
+const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
+static const char *panic_later, *panic_param;
+
+extern const struct obs_kernel_param __setup_start[], __setup_end[];
+
+static int __init obsolete_checksetup(char *line)
+{
+	const struct obs_kernel_param *p;
+	int had_early_param = 0;
+
+	p = __setup_start;
+	do {
+		int n = strlen(p->str);
+		if (!strncmp(line, p->str, n)) {
+			if (p->early) {
+				/* Already done in parse_early_param?
+				 * (Needs exact match on param part).
+				 * Keep iterating, as we can have early
+				 * params and __setups of same names 8( */
+				if (line[n] == '\0' || line[n] == '=')
+					had_early_param = 1;
+			} else if (!p->setup_func) {
+				printk(KERN_WARNING "Parameter %s is obsolete,"
+				       " ignored\n", p->str);
+				return 1;
+			} else if (p->setup_func(line + n))
+				return 1;
+		}
+		p++;
+	} while (p < __setup_end);
+
+	return had_early_param;
+}
+
+/*
+ * This should be approx 2 Bo*oMips to start (note initial shift), and will
+ * still work even if initially too large, it will just take slightly longer
+ */
+unsigned long loops_per_jiffy = (1<<12);
+
+EXPORT_SYMBOL(loops_per_jiffy);
+
+static int __init debug_kernel(char *str)
+{
+	console_loglevel = 10;
+	return 0;
+}
+
+static int __init quiet_kernel(char *str)
+{
+	console_loglevel = 4;
+	return 0;
+}
+
+early_param("debug", debug_kernel);
+early_param("quiet", quiet_kernel);
+
+static int __init loglevel(char *str)
+{
+	get_option(&str, &console_loglevel);
+	return 0;
+}
+
+early_param("loglevel", loglevel);
+
+/*
+ * Unknown boot options get handed to init, unless they look like
+ * unused parameters (modprobe will find them in /proc/cmdline).
+ */
+static int __init unknown_bootoption(char *param, char *val)
+{
+	/* Change NUL term back to "=", to make "param" the whole string. */
+	if (val) {
+		/* param=val or param="val"? */
+		if (val == param+strlen(param)+1)
+			val[-1] = '=';
+		else if (val == param+strlen(param)+2) {
+			val[-2] = '=';
+			memmove(val-1, val, strlen(val)+1);
+			val--;
+		} else
+			BUG();
+	}
+
+	/* Handle obsolete-style parameters */
+	if (obsolete_checksetup(param))
+		return 0;
+
+	/* Unused module parameter. */
+	if (strchr(param, '.') && (!val || strchr(param, '.') < val))
+		return 0;
+
+	if (panic_later)
+		return 0;
+
+	if (val) {
+		/* Environment option */
+		unsigned int i;
+		for (i = 0; envp_init[i]; i++) {
+			if (i == MAX_INIT_ENVS) {
+				panic_later = "Too many boot env vars at `%s'";
+				panic_param = param;
+			}
+			if (!strncmp(param, envp_init[i], val - param))
+				break;
+		}
+		envp_init[i] = param;
+	} else {
+		/* Command line option */
+		unsigned int i;
+		for (i = 0; argv_init[i]; i++) {
+			if (i == MAX_INIT_ARGS) {
+				panic_later = "Too many boot init vars at `%s'";
+				panic_param = param;
+			}
+		}
+		argv_init[i] = param;
+	}
+	return 0;
+}
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+int __read_mostly debug_pagealloc_enabled = 0;
+#endif
+
+static int __init init_setup(char *str)
+{
+	unsigned int i;
+
+	execute_command = str;
+	/*
+	 * In case LILO is going to boot us with default command line,
+	 * it prepends "auto" before the whole cmdline which makes
+	 * the shell think it should execute a script with such name.
+	 * So we ignore all arguments entered _before_ init=... [MJ]
+	 */
+	for (i = 1; i < MAX_INIT_ARGS; i++)
+		argv_init[i] = NULL;
+	return 1;
+}
+__setup("init=", init_setup);
+
+static int __init rdinit_setup(char *str)
+{
+	unsigned int i;
+
+	ramdisk_execute_command = str;
+	/* See "auto" comment in init_setup */
+	for (i = 1; i < MAX_INIT_ARGS; i++)
+		argv_init[i] = NULL;
+	return 1;
+}
+__setup("rdinit=", rdinit_setup);
+
+#ifndef CONFIG_SMP
+static const unsigned int setup_max_cpus = NR_CPUS;
+#ifdef CONFIG_X86_LOCAL_APIC
+static void __init smp_init(void)
+{
+	APIC_init_uniprocessor();
+}
+#else
+#define smp_init()	do { } while (0)
+#endif
+
+static inline void setup_nr_cpu_ids(void) { }
+static inline void smp_prepare_cpus(unsigned int maxcpus) { }
+#endif
+
+/*
+ * We need to store the untouched command line for future reference.
+ * We also need to store the touched command line since the parameter
+ * parsing is performed in place, and we should allow a component to
+ * store reference of name/value for future reference.
+ */
+static void __init setup_command_line(char *command_line)
+{
+	saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
+	static_command_line = alloc_bootmem(strlen (command_line)+1);
+	strcpy (saved_command_line, boot_command_line);
+	strcpy (static_command_line, command_line);
+}
+
+/*
+ * We need to finalize in a non-__init function or else race conditions
+ * between the root thread and the init thread may cause start_kernel to
+ * be reaped by free_initmem before the root thread has proceeded to
+ * cpu_idle.
+ *
+ * gcc-3.4 accidentally inlines this function, so use noinline.
+ */
+
+static __initdata DECLARE_COMPLETION(kthreadd_done);
+
+static noinline void __init_refok rest_init(void)
+{
+	int pid;
+
+	rcu_scheduler_starting();
+	/*
+	 * We need to spawn init first so that it obtains pid 1, however
+	 * the init task will end up wanting to create kthreads, which, if
+	 * we schedule it before we create kthreadd, will OOPS.
+	 */
+	kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
+	numa_default_policy();
+	pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
+	rcu_read_lock();
+	kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
+	rcu_read_unlock();
+	complete(&kthreadd_done);
+
+	/*
+	 * The boot idle thread must execute schedule()
+	 * at least once to get things moving:
+	 */
+	init_idle_bootup_task(current);
+	preempt_enable_no_resched();
+	schedule();
+	preempt_disable();
+
+	/* Call into cpu_idle with preempt disabled */
+	cpu_idle();
+}
+
+/* Check for early params. */
+static int __init do_early_param(char *param, char *val)
+{
+	const struct obs_kernel_param *p;
+
+	for (p = __setup_start; p < __setup_end; p++) {
+		if ((p->early && strcmp(param, p->str) == 0) ||
+		    (strcmp(param, "console") == 0 &&
+		     strcmp(p->str, "earlycon") == 0)
+		) {
+			if (p->setup_func(val) != 0)
+				printk(KERN_WARNING
+				       "Malformed early option '%s'\n", param);
+		}
+	}
+	/* We accept everything at this stage. */
+	return 0;
+}
+
+void __init parse_early_options(char *cmdline)
+{
+	parse_args("early options", cmdline, NULL, 0, do_early_param);
+}
+
+/* Arch code calls this early on, or if not, just before other parsing. */
+void __init parse_early_param(void)
+{
+	static __initdata int done = 0;
+	static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
+
+	if (done)
+		return;
+
+	/* All fall through to do_early_param. */
+	strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
+	parse_early_options(tmp_cmdline);
+	done = 1;
+}
+
+/*
+ *	Activate the first processor.
+ */
+
+static void __init boot_cpu_init(void)
+{
+	int cpu = smp_processor_id();
+	/* Mark the boot cpu "present", "online" etc for SMP and UP case */
+	set_cpu_online(cpu, true);
+	set_cpu_active(cpu, true);
+	set_cpu_present(cpu, true);
+	set_cpu_possible(cpu, true);
+}
+
+void __init __weak smp_setup_processor_id(void)
+{
+}
+
+void __init __weak thread_info_cache_init(void)
+{
+}
+
+/*
+ * Set up kernel memory allocators
+ */
+static void __init mm_init(void)
+{
+	/*
+	 * page_cgroup requires countinous pages as memmap
+	 * and it's bigger than MAX_ORDER unless SPARSEMEM.
+	 */
+	page_cgroup_init_flatmem();
+	mem_init();
+	kmem_cache_init();
+	percpu_init_late();
+	pgtable_cache_init();
+	vmalloc_init();
+}
+
+asmlinkage void __init start_kernel(void)
+{
+	char * command_line;
+	extern const struct kernel_param __start___param[], __stop___param[];
+
+	smp_setup_processor_id();
+
+	/*
+	 * Need to run as early as possible, to initialize the
+	 * lockdep hash:
+	 */
+	lockdep_init();
+	debug_objects_early_init();
+
+	/*
+	 * Set up the the initial canary ASAP:
+	 */
+	boot_init_stack_canary();
+
+	cgroup_init_early();
+
+	local_irq_disable();
+	early_boot_irqs_disabled = true;
+
+/*
+ * Interrupts are still disabled. Do necessary setups, then
+ * enable them
+ */
+	tick_init();
+	boot_cpu_init();
+	page_address_init();
+	printk(KERN_NOTICE "%s", linux_banner);
+	setup_arch(&command_line);
+	mm_init_owner(&init_mm, &init_task);
+	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);
+	page_alloc_init();
+
+	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,
+		   &unknown_bootoption);
+	/*
+	 * 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 (!irqs_disabled()) {
+		printk(KERN_WARNING "start_kernel(): bug: interrupts were "
+				"enabled *very* early, fixing it\n");
+		local_irq_disable();
+	}
+	idr_init_cache();
+	perf_event_init();
+	rcu_init();
+	radix_tree_init();
+	/* init some links before init_ISA_irqs() */
+	early_irq_init();
+	init_IRQ();
+	prio_tree_init();
+	init_timers();
+	hrtimers_init();
+	softirq_init();
+	timekeeping_init();
+	time_init();
+	profile_init();
+	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();
+
+	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(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) {
+		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();
+	enable_debug_pagealloc();
+	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();
+#ifdef CONFIG_X86
+	if (efi_enabled)
+		efi_enter_virtual_mode();
+#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();
+#ifdef CONFIG_PROC_FS
+	proc_root_init();
+#endif
+	cgroup_init();
+	cpuset_init();
+	taskstats_init_early();
+	delayacct_init();
+
+	check_bugs();
+
+	acpi_early_init(); /* before LAPIC and SMP init */
+	sfi_init_late();
+
+	ftrace_init();
+
+	/* Do the rest non-__init'ed, we're now alive */
+	rest_init();
+}
+
+/* Call all constructor functions linked into the kernel. */
+static void __init do_ctors(void)
+{
+#ifdef CONFIG_CONSTRUCTORS
+	ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
+
+	for (; fn < (ctor_fn_t *) __ctors_end; fn++)
+		(*fn)();
+#endif
+}
+
+int initcall_debug;
+core_param(initcall_debug, initcall_debug, bool, 0644);
+
+static char msgbuf[64];
+
+static int __init_or_module do_one_initcall_debug(initcall_t fn)
+{
+	ktime_t calltime, delta, rettime;
+	unsigned long long duration;
+	int ret;
+
+	printk(KERN_DEBUG "calling  %pF @ %i\n", fn, task_pid_nr(current));
+	calltime = ktime_get();
+	ret = fn();
+	rettime = ktime_get();
+	delta = ktime_sub(rettime, calltime);
+	duration = (unsigned long long) ktime_to_ns(delta) >> 10;
+	printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n", fn,
+		ret, duration);
+
+	return ret;
+}
+
+int __init_or_module do_one_initcall(initcall_t fn)
+{
+	int count = preempt_count();
+	int ret;
+
+	if (initcall_debug)
+		ret = do_one_initcall_debug(fn);
+	else
+		ret = fn();
+
+	msgbuf[0] = 0;
+
+	if (ret && ret != -ENODEV && initcall_debug)
+		sprintf(msgbuf, "error code %d ", ret);
+
+	if (preempt_count() != count) {
+		strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
+		preempt_count() = count;
+	}
+	if (irqs_disabled()) {
+		strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
+		local_irq_enable();
+	}
+	if (msgbuf[0]) {
+		printk("initcall %pF returned with %s\n", fn, msgbuf);
+	}
+
+	return ret;
+}
+
+
+extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
+
+static void __init do_initcalls(void)
+{
+	initcall_t *fn;
+
+	for (fn = __early_initcall_end; fn < __initcall_end; fn++)
+		do_one_initcall(*fn);
+}
+
+/*
+ * Ok, the machine is now initialized. None of the devices
+ * have been touched yet, but the CPU subsystem is up and
+ * running, and memory and process management works.
+ *
+ * Now we can finally start doing some real work..
+ */
+static void __init do_basic_setup(void)
+{
+	cpuset_init_smp();
+	usermodehelper_init();
+	init_tmpfs();
+	driver_init();
+	init_irq_proc();
+	do_ctors();
+	do_initcalls();
+}
+
+static void __init do_pre_smp_initcalls(void)
+{
+	initcall_t *fn;
+
+	for (fn = __initcall_start; fn < __early_initcall_end; fn++)
+		do_one_initcall(*fn);
+}
+
+static void run_init_process(const char *init_filename)
+{
+	argv_init[0] = init_filename;
+	kernel_execve(init_filename, argv_init, envp_init);
+}
+
+/* This is a non __init function. Force it to be noinline otherwise gcc
+ * makes it inline to init() and it becomes part of init.text section
+ */
+static noinline int init_post(void)
+{
+	/* need to finish all async __init code before freeing the memory */
+	async_synchronize_full();
+	free_initmem();
+	mark_rodata_ro();
+	system_state = SYSTEM_RUNNING;
+	numa_default_policy();
+
+
+	current->signal->flags |= SIGNAL_UNKILLABLE;
+
+	if (ramdisk_execute_command) {
+		run_init_process(ramdisk_execute_command);
+		printk(KERN_WARNING "Failed to execute %s\n",
+				ramdisk_execute_command);
+	}
+
+	/*
+	 * We try each of these until one succeeds.
+	 *
+	 * The Bourne shell can be used instead of init if we are
+	 * trying to recover a really broken machine.
+	 */
+	if (execute_command) {
+		run_init_process(execute_command);
+		printk(KERN_WARNING "Failed to execute %s.  Attempting "
+					"defaults...\n", execute_command);
+	}
+	run_init_process("/sbin/init");
+	run_init_process("/etc/init");
+	run_init_process("/bin/init");
+	run_init_process("/bin/sh");
+
+	panic("No init found.  Try passing init= option to kernel. "
+	      "See Linux Documentation/init.txt for guidance.");
+}
+
+static int __init kernel_init(void * unused)
+{
+	/*
+	 * Wait until kthreadd is all set-up.
+	 */
+	wait_for_completion(&kthreadd_done);
+
+	/* Now the scheduler is fully set up and can do blocking allocations */
+	gfp_allowed_mask = __GFP_BITS_MASK;
+
+	/*
+	 * init can allocate pages on any node
+	 */
+	set_mems_allowed(node_states[N_HIGH_MEMORY]);
+	/*
+	 * init can run on any cpu.
+	 */
+	set_cpus_allowed_ptr(current, cpu_all_mask);
+
+	cad_pid = task_pid(current);
+
+	smp_prepare_cpus(setup_max_cpus);
+
+	do_pre_smp_initcalls();
+	lockup_detector_init();
+
+	smp_init();
+	sched_init_smp();
+
+	do_basic_setup();
+
+	/* Open the /dev/console on the rootfs, this should never fail */
+	if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
+		printk(KERN_WARNING "Warning: unable to open an initial console.\n");
+
+	(void) sys_dup(0);
+	(void) sys_dup(0);
+	/*
+	 * check if there is an early userspace init.  If yes, let it do all
+	 * the work
+	 */
+
+	if (!ramdisk_execute_command)
+		ramdisk_execute_command = "/init";
+
+	if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
+		ramdisk_execute_command = NULL;
+		prepare_namespace();
+	}
+
+	/*
+	 * Ok, we have completed the initial bootup, and
+	 * we're essentially up and running. Get rid of the
+	 * initmem segments and start the user-mode stuff..
+	 */
+
+	init_post();
+	return 0;
+}