/*
   *  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 (parameqn(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
  ", 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)
  {

  	int newlevel;
  
  	/*
  	 * Only update loglevel value when a correct setting was passed,
  	 * to prevent blind crashes (when loglevel being set to 0) that
  	 * are quite hard to debug
  	 */
  	if (get_option(&str, &newlevel)) {
  		console_loglevel = newlevel;
  		return 0;
  	}
  
  	return -EINVAL;

  }

  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();

  	/* Call into cpu_idle with preempt disabled */

  	preempt_disable();

  	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 && parameq(param, p->str)) ||

  		    (strcmp(param, "console") == 0 &&
  		     strcmp(p->str, "earlycon") == 0)
  		) {

  			if (p->setup_func(val) != 0)
  				printk(KERN_WARNING
  				       "Malformed early option '%s'
  ", 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
  ", boot_command_line);
  	parse_early_param();
  	parse_args("Booting kernel", static_command_line, __start___param,
  		   __stop___param - __start___param,
  		   &unknown_bootoption);

  
  	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 (!irqs_disabled()) {
  		printk(KERN_WARNING "start_kernel(): bug: interrupts were "
  				"enabled *very* early, fixing it
  ");
  		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
  ");

  	early_boot_irqs_disabled = false;

  	local_irq_enable();

  
  	/* Interrupts are enabled now so all GFP allocations are safe. */

  	gfp_allowed_mask = __GFP_BITS_MASK;

  	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.
  ",

  		    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
  ", 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
  ", 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
  ", 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();

  	shmem_init();

  	driver_init();

  	init_irq_proc();

  	do_ctors();

  	usermodehelper_enable();

  	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
  ",
  				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...
  ", 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);

  	/*
  	 * 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.
  ");
  
  	(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;

  }