projects/linux·blob v2.6.25 · refs

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1/*
2 * linux/init/main.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * GK 2/5/95 - Changed to support mounting root fs via NFS
7 * Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
8 * Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
9 * Simplified starting of init: Michael A. Griffith <[email protected]>
10 */
11
12#include <linux/types.h>
13#include <linux/module.h>
14#include <linux/proc_fs.h>
15#include <linux/kernel.h>
16#include <linux/syscalls.h>
17#include <linux/string.h>
18#include <linux/ctype.h>
19#include <linux/delay.h>
20#include <linux/utsname.h>
21#include <linux/ioport.h>
22#include <linux/init.h>
23#include <linux/smp_lock.h>
24#include <linux/initrd.h>
25#include <linux/hdreg.h>
26#include <linux/bootmem.h>
27#include <linux/tty.h>
28#include <linux/gfp.h>
29#include <linux/percpu.h>
30#include <linux/kmod.h>
31#include <linux/kernel_stat.h>
32#include <linux/start_kernel.h>
33#include <linux/security.h>
34#include <linux/workqueue.h>
35#include <linux/profile.h>
36#include <linux/rcupdate.h>
37#include <linux/moduleparam.h>
38#include <linux/kallsyms.h>
39#include <linux/writeback.h>
40#include <linux/cpu.h>
41#include <linux/cpuset.h>
42#include <linux/cgroup.h>
43#include <linux/efi.h>
44#include <linux/tick.h>
45#include <linux/interrupt.h>
46#include <linux/taskstats_kern.h>
47#include <linux/delayacct.h>
48#include <linux/unistd.h>
49#include <linux/rmap.h>
50#include <linux/mempolicy.h>
51#include <linux/key.h>
52#include <linux/unwind.h>
53#include <linux/buffer_head.h>
54#include <linux/debug_locks.h>
55#include <linux/lockdep.h>
56#include <linux/pid_namespace.h>
57#include <linux/device.h>
58#include <linux/kthread.h>
59#include <linux/sched.h>
60#include <linux/signal.h>
61
62#include <asm/io.h>
63#include <asm/bugs.h>
64#include <asm/setup.h>
65#include <asm/sections.h>
66#include <asm/cacheflush.h>
67
68#ifdef CONFIG_X86_LOCAL_APIC
69#include <asm/smp.h>
70#endif
71
72/*
73 * This is one of the first .c files built. Error out early if we have compiler
74 * trouble.
75 */
76
77#if __GNUC__ == 4 && __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ == 0
78#warning gcc-4.1.0 is known to miscompile the kernel. A different compiler version is recommended.
79#endif
80
81static int kernel_init(void *);
82
83extern void init_IRQ(void);
84extern void fork_init(unsigned long);
85extern void mca_init(void);
86extern void sbus_init(void);
87extern void pidhash_init(void);
88extern void pidmap_init(void);
89extern void prio_tree_init(void);
90extern void radix_tree_init(void);
91extern void free_initmem(void);
92#ifdef CONFIG_ACPI
93extern void acpi_early_init(void);
94#else
95static inline void acpi_early_init(void) { }
96#endif
97#ifndef CONFIG_DEBUG_RODATA
98static inline void mark_rodata_ro(void) { }
99#endif
100
101#ifdef CONFIG_TC
102extern void tc_init(void);
103#endif
104
105enum system_states system_state;
106EXPORT_SYMBOL(system_state);
107
108/*
109 * Boot command-line arguments
110 */
111#define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
112#define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
113
114extern void time_init(void);
115/* Default late time init is NULL. archs can override this later. */
116void (*late_time_init)(void);
117extern void softirq_init(void);
118
119/* Untouched command line saved by arch-specific code. */
120char __initdata boot_command_line[COMMAND_LINE_SIZE];
121/* Untouched saved command line (eg. for /proc) */
122char *saved_command_line;
123/* Command line for parameter parsing */
124static char *static_command_line;
125
126static char *execute_command;
127static char *ramdisk_execute_command;
128
129#ifdef CONFIG_SMP
130/* Setup configured maximum number of CPUs to activate */
131unsigned int __initdata setup_max_cpus = NR_CPUS;
132
133/*
134 * Setup routine for controlling SMP activation
135 *
136 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
137 * activation entirely (the MPS table probe still happens, though).
138 *
139 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
140 * greater than 0, limits the maximum number of CPUs activated in
141 * SMP mode to <NUM>.
142 */
143#ifndef CONFIG_X86_IO_APIC
144static inline void disable_ioapic_setup(void) {};
145#endif
146
147static int __init nosmp(char *str)
148{
149 setup_max_cpus = 0;
150 disable_ioapic_setup();
151 return 0;
152}
153
154early_param("nosmp", nosmp);
155
156static int __init maxcpus(char *str)
157{
158 get_option(&str, &setup_max_cpus);
159 if (setup_max_cpus == 0)
160 disable_ioapic_setup();
161
162 return 0;
163}
164
165early_param("maxcpus", maxcpus);
166#else
167#define setup_max_cpus NR_CPUS
168#endif
169
170/*
171 * If set, this is an indication to the drivers that reset the underlying
172 * device before going ahead with the initialization otherwise driver might
173 * rely on the BIOS and skip the reset operation.
174 *
175 * This is useful if kernel is booting in an unreliable environment.
176 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
177 * skipped and devices will be in unknown state.
178 */
179unsigned int reset_devices;
180EXPORT_SYMBOL(reset_devices);
181
182static int __init set_reset_devices(char *str)
183{
184 reset_devices = 1;
185 return 1;
186}
187
188__setup("reset_devices", set_reset_devices);
189
190static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
191char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
192static const char *panic_later, *panic_param;
193
194extern struct obs_kernel_param __setup_start[], __setup_end[];
195
196static int __init obsolete_checksetup(char *line)
197{
198 struct obs_kernel_param *p;
199 int had_early_param = 0;
200
201 p = __setup_start;
202 do {
203 int n = strlen(p->str);
204 if (!strncmp(line, p->str, n)) {
205 if (p->early) {
206 /* Already done in parse_early_param?
207 * (Needs exact match on param part).
208 * Keep iterating, as we can have early
209 * params and __setups of same names 8( */
210 if (line[n] == '\0' || line[n] == '=')
211 had_early_param = 1;
212 } else if (!p->setup_func) {
213 printk(KERN_WARNING "Parameter %s is obsolete,"
214 " ignored\n", p->str);
215 return 1;
216 } else if (p->setup_func(line + n))
217 return 1;
218 }
219 p++;
220 } while (p < __setup_end);
221
222 return had_early_param;
223}
224
225/*
226 * This should be approx 2 Bo*oMips to start (note initial shift), and will
227 * still work even if initially too large, it will just take slightly longer
228 */
229unsigned long loops_per_jiffy = (1<<12);
230
231EXPORT_SYMBOL(loops_per_jiffy);
232
233static int __init debug_kernel(char *str)
234{
235 console_loglevel = 10;
236 return 0;
237}
238
239static int __init quiet_kernel(char *str)
240{
241 console_loglevel = 4;
242 return 0;
243}
244
245early_param("debug", debug_kernel);
246early_param("quiet", quiet_kernel);
247
248static int __init loglevel(char *str)
249{
250 get_option(&str, &console_loglevel);
251 return 0;
252}
253
254early_param("loglevel", loglevel);
255
256/*
257 * Unknown boot options get handed to init, unless they look like
258 * failed parameters
259 */
260static int __init unknown_bootoption(char *param, char *val)
261{
262 /* Change NUL term back to "=", to make "param" the whole string. */
263 if (val) {
264 /* param=val or param="val"? */
265 if (val == param+strlen(param)+1)
266 val[-1] = '=';
267 else if (val == param+strlen(param)+2) {
268 val[-2] = '=';
269 memmove(val-1, val, strlen(val)+1);
270 val--;
271 } else
272 BUG();
273 }
274
275 /* Handle obsolete-style parameters */
276 if (obsolete_checksetup(param))
277 return 0;
278
279 /*
280 * Preemptive maintenance for "why didn't my misspelled command
281 * line work?"
282 */
283 if (strchr(param, '.') && (!val || strchr(param, '.') < val)) {
284 printk(KERN_ERR "Unknown boot option `%s': ignoring\n", param);
285 return 0;
286 }
287
288 if (panic_later)
289 return 0;
290
291 if (val) {
292 /* Environment option */
293 unsigned int i;
294 for (i = 0; envp_init[i]; i++) {
295 if (i == MAX_INIT_ENVS) {
296 panic_later = "Too many boot env vars at `%s'";
297 panic_param = param;
298 }
299 if (!strncmp(param, envp_init[i], val - param))
300 break;
301 }
302 envp_init[i] = param;
303 } else {
304 /* Command line option */
305 unsigned int i;
306 for (i = 0; argv_init[i]; i++) {
307 if (i == MAX_INIT_ARGS) {
308 panic_later = "Too many boot init vars at `%s'";
309 panic_param = param;
310 }
311 }
312 argv_init[i] = param;
313 }
314 return 0;
315}
316
317#ifdef CONFIG_DEBUG_PAGEALLOC
318int __read_mostly debug_pagealloc_enabled = 0;
319#endif
320
321static int __init init_setup(char *str)
322{
323 unsigned int i;
324
325 execute_command = str;
326 /*
327 * In case LILO is going to boot us with default command line,
328 * it prepends "auto" before the whole cmdline which makes
329 * the shell think it should execute a script with such name.
330 * So we ignore all arguments entered _before_ init=... [MJ]
331 */
332 for (i = 1; i < MAX_INIT_ARGS; i++)
333 argv_init[i] = NULL;
334 return 1;
335}
336__setup("init=", init_setup);
337
338static int __init rdinit_setup(char *str)
339{
340 unsigned int i;
341
342 ramdisk_execute_command = str;
343 /* See "auto" comment in init_setup */
344 for (i = 1; i < MAX_INIT_ARGS; i++)
345 argv_init[i] = NULL;
346 return 1;
347}
348__setup("rdinit=", rdinit_setup);
349
350#ifndef CONFIG_SMP
351
352#ifdef CONFIG_X86_LOCAL_APIC
353static void __init smp_init(void)
354{
355 APIC_init_uniprocessor();
356}
357#else
358#define smp_init() do { } while (0)
359#endif
360
361static inline void setup_per_cpu_areas(void) { }
362static inline void smp_prepare_cpus(unsigned int maxcpus) { }
363
364#else
365
366#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
367unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
368
369EXPORT_SYMBOL(__per_cpu_offset);
370
371static void __init setup_per_cpu_areas(void)
372{
373 unsigned long size, i;
374 char *ptr;
375 unsigned long nr_possible_cpus = num_possible_cpus();
376
377 /* Copy section for each CPU (we discard the original) */
378 size = ALIGN(PERCPU_ENOUGH_ROOM, PAGE_SIZE);
379 ptr = alloc_bootmem_pages(size * nr_possible_cpus);
380
381 for_each_possible_cpu(i) {
382 __per_cpu_offset[i] = ptr - __per_cpu_start;
383 memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
384 ptr += size;
385 }
386}
387#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
388
389/* Called by boot processor to activate the rest. */
390static void __init smp_init(void)
391{
392 unsigned int cpu;
393
394 /* FIXME: This should be done in userspace --RR */
395 for_each_present_cpu(cpu) {
396 if (num_online_cpus() >= setup_max_cpus)
397 break;
398 if (!cpu_online(cpu))
399 cpu_up(cpu);
400 }
401
402 /* Any cleanup work */
403 printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
404 smp_cpus_done(setup_max_cpus);
405}
406
407#endif
408
409/*
410 * We need to store the untouched command line for future reference.
411 * We also need to store the touched command line since the parameter
412 * parsing is performed in place, and we should allow a component to
413 * store reference of name/value for future reference.
414 */
415static void __init setup_command_line(char *command_line)
416{
417 saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
418 static_command_line = alloc_bootmem(strlen (command_line)+1);
419 strcpy (saved_command_line, boot_command_line);
420 strcpy (static_command_line, command_line);
421}
422
423/*
424 * We need to finalize in a non-__init function or else race conditions
425 * between the root thread and the init thread may cause start_kernel to
426 * be reaped by free_initmem before the root thread has proceeded to
427 * cpu_idle.
428 *
429 * gcc-3.4 accidentally inlines this function, so use noinline.
430 */
431
432static void noinline __init_refok rest_init(void)
433 __releases(kernel_lock)
434{
435 int pid;
436
437 kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
438 numa_default_policy();
439 pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
440 kthreadd_task = find_task_by_pid(pid);
441 unlock_kernel();
442
443 /*
444 * The boot idle thread must execute schedule()
445 * at least once to get things moving:
446 */
447 init_idle_bootup_task(current);
448 preempt_enable_no_resched();
449 schedule();
450 preempt_disable();
451
452 /* Call into cpu_idle with preempt disabled */
453 cpu_idle();
454}
455
456/* Check for early params. */
457static int __init do_early_param(char *param, char *val)
458{
459 struct obs_kernel_param *p;
460
461 for (p = __setup_start; p < __setup_end; p++) {
462 if ((p->early && strcmp(param, p->str) == 0) ||
463 (strcmp(param, "console") == 0 &&
464 strcmp(p->str, "earlycon") == 0)
465 ) {
466 if (p->setup_func(val) != 0)
467 printk(KERN_WARNING
468 "Malformed early option '%s'\n", param);
469 }
470 }
471 /* We accept everything at this stage. */
472 return 0;
473}
474
475/* Arch code calls this early on, or if not, just before other parsing. */
476void __init parse_early_param(void)
477{
478 static __initdata int done = 0;
479 static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
480
481 if (done)
482 return;
483
484 /* All fall through to do_early_param. */
485 strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
486 parse_args("early options", tmp_cmdline, NULL, 0, do_early_param);
487 done = 1;
488}
489
490/*
491 * Activate the first processor.
492 */
493
494static void __init boot_cpu_init(void)
495{
496 int cpu = smp_processor_id();
497 /* Mark the boot cpu "present", "online" etc for SMP and UP case */
498 cpu_set(cpu, cpu_online_map);
499 cpu_set(cpu, cpu_present_map);
500 cpu_set(cpu, cpu_possible_map);
501}
502
503void __init __attribute__((weak)) smp_setup_processor_id(void)
504{
505}
506
507asmlinkage void __init start_kernel(void)
508{
509 char * command_line;
510 extern struct kernel_param __start___param[], __stop___param[];
511
512 smp_setup_processor_id();
513
514 /*
515 * Need to run as early as possible, to initialize the
516 * lockdep hash:
517 */
518 unwind_init();
519 lockdep_init();
520 cgroup_init_early();
521
522 local_irq_disable();
523 early_boot_irqs_off();
524 early_init_irq_lock_class();
525
526/*
527 * Interrupts are still disabled. Do necessary setups, then
528 * enable them
529 */
530 lock_kernel();
531 tick_init();
532 boot_cpu_init();
533 page_address_init();
534 printk(KERN_NOTICE);
535 printk(linux_banner);
536 setup_arch(&command_line);
537 setup_command_line(command_line);
538 unwind_setup();
539 setup_per_cpu_areas();
540 smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
541
542 /*
543 * Set up the scheduler prior starting any interrupts (such as the
544 * timer interrupt). Full topology setup happens at smp_init()
545 * time - but meanwhile we still have a functioning scheduler.
546 */
547 sched_init();
548 /*
549 * Disable preemption - early bootup scheduling is extremely
550 * fragile until we cpu_idle() for the first time.
551 */
552 preempt_disable();
553 build_all_zonelists();
554 page_alloc_init();
555 printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
556 parse_early_param();
557 parse_args("Booting kernel", static_command_line, __start___param,
558 __stop___param - __start___param,
559 &unknown_bootoption);
560 if (!irqs_disabled()) {
561 printk(KERN_WARNING "start_kernel(): bug: interrupts were "
562 "enabled *very* early, fixing it\n");
563 local_irq_disable();
564 }
565 sort_main_extable();
566 trap_init();
567 rcu_init();
568 init_IRQ();
569 pidhash_init();
570 init_timers();
571 hrtimers_init();
572 softirq_init();
573 timekeeping_init();
574 time_init();
575 profile_init();
576 if (!irqs_disabled())
577 printk("start_kernel(): bug: interrupts were enabled early\n");
578 early_boot_irqs_on();
579 local_irq_enable();
580
581 /*
582 * HACK ALERT! This is early. We're enabling the console before
583 * we've done PCI setups etc, and console_init() must be aware of
584 * this. But we do want output early, in case something goes wrong.
585 */
586 console_init();
587 if (panic_later)
588 panic(panic_later, panic_param);
589
590 lockdep_info();
591
592 /*
593 * Need to run this when irqs are enabled, because it wants
594 * to self-test [hard/soft]-irqs on/off lock inversion bugs
595 * too:
596 */
597 locking_selftest();
598
599#ifdef CONFIG_BLK_DEV_INITRD
600 if (initrd_start && !initrd_below_start_ok &&
601 initrd_start < min_low_pfn << PAGE_SHIFT) {
602 printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
603 "disabling it.\n",initrd_start,min_low_pfn << PAGE_SHIFT);
604 initrd_start = 0;
605 }
606#endif
607 vfs_caches_init_early();
608 cpuset_init_early();
609 mem_init();
610 enable_debug_pagealloc();
611 cpu_hotplug_init();
612 kmem_cache_init();
613 setup_per_cpu_pageset();
614 numa_policy_init();
615 if (late_time_init)
616 late_time_init();
617 calibrate_delay();
618 pidmap_init();
619 pgtable_cache_init();
620 prio_tree_init();
621 anon_vma_init();
622#ifdef CONFIG_X86
623 if (efi_enabled)
624 efi_enter_virtual_mode();
625#endif
626 fork_init(num_physpages);
627 proc_caches_init();
628 buffer_init();
629 unnamed_dev_init();
630 key_init();
631 security_init();
632 vfs_caches_init(num_physpages);
633 radix_tree_init();
634 signals_init();
635 /* rootfs populating might need page-writeback */
636 page_writeback_init();
637#ifdef CONFIG_PROC_FS
638 proc_root_init();
639#endif
640 cgroup_init();
641 cpuset_init();
642 taskstats_init_early();
643 delayacct_init();
644
645 check_bugs();
646
647 acpi_early_init(); /* before LAPIC and SMP init */
648
649 /* Do the rest non-__init'ed, we're now alive */
650 rest_init();
651}
652
653static int __initdata initcall_debug;
654
655static int __init initcall_debug_setup(char *str)
656{
657 initcall_debug = 1;
658 return 1;
659}
660__setup("initcall_debug", initcall_debug_setup);
661
662extern initcall_t __initcall_start[], __initcall_end[];
663
664static void __init do_initcalls(void)
665{
666 initcall_t *call;
667 int count = preempt_count();
668
669 for (call = __initcall_start; call < __initcall_end; call++) {
670 ktime_t t0, t1, delta;
671 char *msg = NULL;
672 char msgbuf[40];
673 int result;
674
675 if (initcall_debug) {
676 printk("Calling initcall 0x%p", *call);
677 print_fn_descriptor_symbol(": %s()",
678 (unsigned long) *call);
679 printk("\n");
680 t0 = ktime_get();
681 }
682
683 result = (*call)();
684
685 if (initcall_debug) {
686 t1 = ktime_get();
687 delta = ktime_sub(t1, t0);
688
689 printk("initcall 0x%p", *call);
690 print_fn_descriptor_symbol(": %s()",
691 (unsigned long) *call);
692 printk(" returned %d.\n", result);
693
694 printk("initcall 0x%p ran for %Ld msecs: ",
695 *call, (unsigned long long)delta.tv64 >> 20);
696 print_fn_descriptor_symbol("%s()\n",
697 (unsigned long) *call);
698 }
699
700 if (result && result != -ENODEV && initcall_debug) {
701 sprintf(msgbuf, "error code %d", result);
702 msg = msgbuf;
703 }
704 if (preempt_count() != count) {
705 msg = "preemption imbalance";
706 preempt_count() = count;
707 }
708 if (irqs_disabled()) {
709 msg = "disabled interrupts";
710 local_irq_enable();
711 }
712 if (msg) {
713 printk(KERN_WARNING "initcall at 0x%p", *call);
714 print_fn_descriptor_symbol(": %s()",
715 (unsigned long) *call);
716 printk(": returned with %s\n", msg);
717 }
718 }
719
720 /* Make sure there is no pending stuff from the initcall sequence */
721 flush_scheduled_work();
722}
723
724/*
725 * Ok, the machine is now initialized. None of the devices
726 * have been touched yet, but the CPU subsystem is up and
727 * running, and memory and process management works.
728 *
729 * Now we can finally start doing some real work..
730 */
731static void __init do_basic_setup(void)
732{
733 /* drivers will send hotplug events */
734 init_workqueues();
735 usermodehelper_init();
736 driver_init();
737 init_irq_proc();
738 do_initcalls();
739}
740
741static int __initdata nosoftlockup;
742
743static int __init nosoftlockup_setup(char *str)
744{
745 nosoftlockup = 1;
746 return 1;
747}
748__setup("nosoftlockup", nosoftlockup_setup);
749
750static void __init do_pre_smp_initcalls(void)
751{
752 extern int spawn_ksoftirqd(void);
753
754 migration_init();
755 spawn_ksoftirqd();
756 if (!nosoftlockup)
757 spawn_softlockup_task();
758}
759
760static void run_init_process(char *init_filename)
761{
762 argv_init[0] = init_filename;
763 kernel_execve(init_filename, argv_init, envp_init);
764}
765
766/* This is a non __init function. Force it to be noinline otherwise gcc
767 * makes it inline to init() and it becomes part of init.text section
768 */
769static int noinline init_post(void)
770{
771 free_initmem();
772 unlock_kernel();
773 mark_rodata_ro();
774 system_state = SYSTEM_RUNNING;
775 numa_default_policy();
776
777 if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
778 printk(KERN_WARNING "Warning: unable to open an initial console.\n");
779
780 (void) sys_dup(0);
781 (void) sys_dup(0);
782
783 if (ramdisk_execute_command) {
784 run_init_process(ramdisk_execute_command);
785 printk(KERN_WARNING "Failed to execute %s\n",
786 ramdisk_execute_command);
787 }
788
789 /*
790 * We try each of these until one succeeds.
791 *
792 * The Bourne shell can be used instead of init if we are
793 * trying to recover a really broken machine.
794 */
795 if (execute_command) {
796 run_init_process(execute_command);
797 printk(KERN_WARNING "Failed to execute %s. Attempting "
798 "defaults...\n", execute_command);
799 }
800 run_init_process("/sbin/init");
801 run_init_process("/etc/init");
802 run_init_process("/bin/init");
803 run_init_process("/bin/sh");
804
805 panic("No init found. Try passing init= option to kernel.");
806}
807
808static int __init kernel_init(void * unused)
809{
810 lock_kernel();
811 /*
812 * init can run on any cpu.
813 */
814 set_cpus_allowed(current, CPU_MASK_ALL);
815 /*
816 * Tell the world that we're going to be the grim
817 * reaper of innocent orphaned children.
818 *
819 * We don't want people to have to make incorrect
820 * assumptions about where in the task array this
821 * can be found.
822 */
823 init_pid_ns.child_reaper = current;
824
825 cad_pid = task_pid(current);
826
827 smp_prepare_cpus(setup_max_cpus);
828
829 do_pre_smp_initcalls();
830
831 smp_init();
832 sched_init_smp();
833
834 cpuset_init_smp();
835
836 do_basic_setup();
837
838 /*
839 * check if there is an early userspace init. If yes, let it do all
840 * the work
841 */
842
843 if (!ramdisk_execute_command)
844 ramdisk_execute_command = "/init";
845
846 if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
847 ramdisk_execute_command = NULL;
848 prepare_namespace();
849 }
850
851 /*
852 * Ok, we have completed the initial bootup, and
853 * we're essentially up and running. Get rid of the
854 * initmem segments and start the user-mode stuff..
855 */
856 init_post();
857 return 0;
858}