drm/i915: fix corruptions on i8xx due to relaxed fencing
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / init / main.c
blob33c37c379e96458521a0111a968849139edcf586
1 /*
2 * linux/init/main.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
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 <grif@acm.org>
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/stackprotector.h>
18 #include <linux/string.h>
19 #include <linux/ctype.h>
20 #include <linux/delay.h>
21 #include <linux/ioport.h>
22 #include <linux/init.h>
23 #include <linux/initrd.h>
24 #include <linux/bootmem.h>
25 #include <linux/acpi.h>
26 #include <linux/tty.h>
27 #include <linux/percpu.h>
28 #include <linux/kmod.h>
29 #include <linux/vmalloc.h>
30 #include <linux/kernel_stat.h>
31 #include <linux/start_kernel.h>
32 #include <linux/security.h>
33 #include <linux/smp.h>
34 #include <linux/profile.h>
35 #include <linux/rcupdate.h>
36 #include <linux/moduleparam.h>
37 #include <linux/kallsyms.h>
38 #include <linux/writeback.h>
39 #include <linux/cpu.h>
40 #include <linux/cpuset.h>
41 #include <linux/cgroup.h>
42 #include <linux/efi.h>
43 #include <linux/tick.h>
44 #include <linux/interrupt.h>
45 #include <linux/taskstats_kern.h>
46 #include <linux/delayacct.h>
47 #include <linux/unistd.h>
48 #include <linux/rmap.h>
49 #include <linux/mempolicy.h>
50 #include <linux/key.h>
51 #include <linux/buffer_head.h>
52 #include <linux/page_cgroup.h>
53 #include <linux/debug_locks.h>
54 #include <linux/debugobjects.h>
55 #include <linux/lockdep.h>
56 #include <linux/kmemleak.h>
57 #include <linux/pid_namespace.h>
58 #include <linux/device.h>
59 #include <linux/kthread.h>
60 #include <linux/sched.h>
61 #include <linux/signal.h>
62 #include <linux/idr.h>
63 #include <linux/kgdb.h>
64 #include <linux/ftrace.h>
65 #include <linux/async.h>
66 #include <linux/kmemcheck.h>
67 #include <linux/sfi.h>
68 #include <linux/shmem_fs.h>
69 #include <linux/slab.h>
70 #include <linux/perf_event.h>
72 #include <asm/io.h>
73 #include <asm/bugs.h>
74 #include <asm/setup.h>
75 #include <asm/sections.h>
76 #include <asm/cacheflush.h>
78 #ifdef CONFIG_X86_LOCAL_APIC
79 #include <asm/smp.h>
80 #endif
82 static int kernel_init(void *);
84 extern void init_IRQ(void);
85 extern void fork_init(unsigned long);
86 extern void mca_init(void);
87 extern void sbus_init(void);
88 extern void prio_tree_init(void);
89 extern void radix_tree_init(void);
90 extern void free_initmem(void);
91 #ifndef CONFIG_DEBUG_RODATA
92 static inline void mark_rodata_ro(void) { }
93 #endif
95 #ifdef CONFIG_TC
96 extern void tc_init(void);
97 #endif
100 * Debug helper: via this flag we know that we are in 'early bootup code'
101 * where only the boot processor is running with IRQ disabled. This means
102 * two things - IRQ must not be enabled before the flag is cleared and some
103 * operations which are not allowed with IRQ disabled are allowed while the
104 * flag is set.
106 bool early_boot_irqs_disabled __read_mostly;
108 enum system_states system_state __read_mostly;
109 EXPORT_SYMBOL(system_state);
112 * Boot command-line arguments
114 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
115 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
117 extern void time_init(void);
118 /* Default late time init is NULL. archs can override this later. */
119 void (*__initdata late_time_init)(void);
120 extern void softirq_init(void);
122 /* Untouched command line saved by arch-specific code. */
123 char __initdata boot_command_line[COMMAND_LINE_SIZE];
124 /* Untouched saved command line (eg. for /proc) */
125 char *saved_command_line;
126 /* Command line for parameter parsing */
127 static char *static_command_line;
129 static char *execute_command;
130 static char *ramdisk_execute_command;
132 #ifdef CONFIG_SMP
133 /* Setup configured maximum number of CPUs to activate */
134 unsigned int setup_max_cpus = NR_CPUS;
135 EXPORT_SYMBOL(setup_max_cpus);
139 * Setup routine for controlling SMP activation
141 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
142 * activation entirely (the MPS table probe still happens, though).
144 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
145 * greater than 0, limits the maximum number of CPUs activated in
146 * SMP mode to <NUM>.
149 void __weak arch_disable_smp_support(void) { }
151 static int __init nosmp(char *str)
153 setup_max_cpus = 0;
154 arch_disable_smp_support();
156 return 0;
159 early_param("nosmp", nosmp);
161 /* this is hard limit */
162 static int __init nrcpus(char *str)
164 int nr_cpus;
166 get_option(&str, &nr_cpus);
167 if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
168 nr_cpu_ids = nr_cpus;
170 return 0;
173 early_param("nr_cpus", nrcpus);
175 static int __init maxcpus(char *str)
177 get_option(&str, &setup_max_cpus);
178 if (setup_max_cpus == 0)
179 arch_disable_smp_support();
181 return 0;
184 early_param("maxcpus", maxcpus);
185 #else
186 static const unsigned int setup_max_cpus = NR_CPUS;
187 #endif
190 * If set, this is an indication to the drivers that reset the underlying
191 * device before going ahead with the initialization otherwise driver might
192 * rely on the BIOS and skip the reset operation.
194 * This is useful if kernel is booting in an unreliable environment.
195 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
196 * skipped and devices will be in unknown state.
198 unsigned int reset_devices;
199 EXPORT_SYMBOL(reset_devices);
201 static int __init set_reset_devices(char *str)
203 reset_devices = 1;
204 return 1;
207 __setup("reset_devices", set_reset_devices);
209 static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
210 const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
211 static const char *panic_later, *panic_param;
213 extern const struct obs_kernel_param __setup_start[], __setup_end[];
215 static int __init obsolete_checksetup(char *line)
217 const struct obs_kernel_param *p;
218 int had_early_param = 0;
220 p = __setup_start;
221 do {
222 int n = strlen(p->str);
223 if (!strncmp(line, p->str, n)) {
224 if (p->early) {
225 /* Already done in parse_early_param?
226 * (Needs exact match on param part).
227 * Keep iterating, as we can have early
228 * params and __setups of same names 8( */
229 if (line[n] == '\0' || line[n] == '=')
230 had_early_param = 1;
231 } else if (!p->setup_func) {
232 printk(KERN_WARNING "Parameter %s is obsolete,"
233 " ignored\n", p->str);
234 return 1;
235 } else if (p->setup_func(line + n))
236 return 1;
238 p++;
239 } while (p < __setup_end);
241 return had_early_param;
245 * This should be approx 2 Bo*oMips to start (note initial shift), and will
246 * still work even if initially too large, it will just take slightly longer
248 unsigned long loops_per_jiffy = (1<<12);
250 EXPORT_SYMBOL(loops_per_jiffy);
252 static int __init debug_kernel(char *str)
254 console_loglevel = 10;
255 return 0;
258 static int __init quiet_kernel(char *str)
260 console_loglevel = 4;
261 return 0;
264 early_param("debug", debug_kernel);
265 early_param("quiet", quiet_kernel);
267 static int __init loglevel(char *str)
269 get_option(&str, &console_loglevel);
270 return 0;
273 early_param("loglevel", loglevel);
276 * Unknown boot options get handed to init, unless they look like
277 * unused parameters (modprobe will find them in /proc/cmdline).
279 static int __init unknown_bootoption(char *param, char *val)
281 /* Change NUL term back to "=", to make "param" the whole string. */
282 if (val) {
283 /* param=val or param="val"? */
284 if (val == param+strlen(param)+1)
285 val[-1] = '=';
286 else if (val == param+strlen(param)+2) {
287 val[-2] = '=';
288 memmove(val-1, val, strlen(val)+1);
289 val--;
290 } else
291 BUG();
294 /* Handle obsolete-style parameters */
295 if (obsolete_checksetup(param))
296 return 0;
298 /* Unused module parameter. */
299 if (strchr(param, '.') && (!val || strchr(param, '.') < val))
300 return 0;
302 if (panic_later)
303 return 0;
305 if (val) {
306 /* Environment option */
307 unsigned int i;
308 for (i = 0; envp_init[i]; i++) {
309 if (i == MAX_INIT_ENVS) {
310 panic_later = "Too many boot env vars at `%s'";
311 panic_param = param;
313 if (!strncmp(param, envp_init[i], val - param))
314 break;
316 envp_init[i] = param;
317 } else {
318 /* Command line option */
319 unsigned int i;
320 for (i = 0; argv_init[i]; i++) {
321 if (i == MAX_INIT_ARGS) {
322 panic_later = "Too many boot init vars at `%s'";
323 panic_param = param;
326 argv_init[i] = param;
328 return 0;
331 #ifdef CONFIG_DEBUG_PAGEALLOC
332 int __read_mostly debug_pagealloc_enabled = 0;
333 #endif
335 static int __init init_setup(char *str)
337 unsigned int i;
339 execute_command = str;
341 * In case LILO is going to boot us with default command line,
342 * it prepends "auto" before the whole cmdline which makes
343 * the shell think it should execute a script with such name.
344 * So we ignore all arguments entered _before_ init=... [MJ]
346 for (i = 1; i < MAX_INIT_ARGS; i++)
347 argv_init[i] = NULL;
348 return 1;
350 __setup("init=", init_setup);
352 static int __init rdinit_setup(char *str)
354 unsigned int i;
356 ramdisk_execute_command = str;
357 /* See "auto" comment in init_setup */
358 for (i = 1; i < MAX_INIT_ARGS; i++)
359 argv_init[i] = NULL;
360 return 1;
362 __setup("rdinit=", rdinit_setup);
364 #ifndef CONFIG_SMP
366 #ifdef CONFIG_X86_LOCAL_APIC
367 static void __init smp_init(void)
369 APIC_init_uniprocessor();
371 #else
372 #define smp_init() do { } while (0)
373 #endif
375 static inline void setup_nr_cpu_ids(void) { }
376 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
378 #else
380 /* Setup number of possible processor ids */
381 int nr_cpu_ids __read_mostly = NR_CPUS;
382 EXPORT_SYMBOL(nr_cpu_ids);
384 /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
385 static void __init setup_nr_cpu_ids(void)
387 nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
390 /* Called by boot processor to activate the rest. */
391 static void __init smp_init(void)
393 unsigned int cpu;
395 /* FIXME: This should be done in userspace --RR */
396 for_each_present_cpu(cpu) {
397 if (num_online_cpus() >= setup_max_cpus)
398 break;
399 if (!cpu_online(cpu))
400 cpu_up(cpu);
403 /* Any cleanup work */
404 printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
405 smp_cpus_done(setup_max_cpus);
408 #endif
411 * We need to store the untouched command line for future reference.
412 * We also need to store the touched command line since the parameter
413 * parsing is performed in place, and we should allow a component to
414 * store reference of name/value for future reference.
416 static void __init setup_command_line(char *command_line)
418 saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
419 static_command_line = alloc_bootmem(strlen (command_line)+1);
420 strcpy (saved_command_line, boot_command_line);
421 strcpy (static_command_line, command_line);
425 * We need to finalize in a non-__init function or else race conditions
426 * between the root thread and the init thread may cause start_kernel to
427 * be reaped by free_initmem before the root thread has proceeded to
428 * cpu_idle.
430 * gcc-3.4 accidentally inlines this function, so use noinline.
433 static __initdata DECLARE_COMPLETION(kthreadd_done);
435 static noinline void __init_refok rest_init(void)
437 int pid;
439 rcu_scheduler_starting();
441 * We need to spawn init first so that it obtains pid 1, however
442 * the init task will end up wanting to create kthreads, which, if
443 * we schedule it before we create kthreadd, will OOPS.
445 kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
446 numa_default_policy();
447 pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
448 rcu_read_lock();
449 kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
450 rcu_read_unlock();
451 complete(&kthreadd_done);
454 * The boot idle thread must execute schedule()
455 * at least once to get things moving:
457 init_idle_bootup_task(current);
458 preempt_enable_no_resched();
459 schedule();
460 preempt_disable();
462 /* Call into cpu_idle with preempt disabled */
463 cpu_idle();
466 /* Check for early params. */
467 static int __init do_early_param(char *param, char *val)
469 const struct obs_kernel_param *p;
471 for (p = __setup_start; p < __setup_end; p++) {
472 if ((p->early && strcmp(param, p->str) == 0) ||
473 (strcmp(param, "console") == 0 &&
474 strcmp(p->str, "earlycon") == 0)
476 if (p->setup_func(val) != 0)
477 printk(KERN_WARNING
478 "Malformed early option '%s'\n", param);
481 /* We accept everything at this stage. */
482 return 0;
485 void __init parse_early_options(char *cmdline)
487 parse_args("early options", cmdline, NULL, 0, do_early_param);
490 /* Arch code calls this early on, or if not, just before other parsing. */
491 void __init parse_early_param(void)
493 static __initdata int done = 0;
494 static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
496 if (done)
497 return;
499 /* All fall through to do_early_param. */
500 strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
501 parse_early_options(tmp_cmdline);
502 done = 1;
506 * Activate the first processor.
509 static void __init boot_cpu_init(void)
511 int cpu = smp_processor_id();
512 /* Mark the boot cpu "present", "online" etc for SMP and UP case */
513 set_cpu_online(cpu, true);
514 set_cpu_active(cpu, true);
515 set_cpu_present(cpu, true);
516 set_cpu_possible(cpu, true);
519 void __init __weak smp_setup_processor_id(void)
523 void __init __weak thread_info_cache_init(void)
528 * Set up kernel memory allocators
530 static void __init mm_init(void)
533 * page_cgroup requires countinous pages as memmap
534 * and it's bigger than MAX_ORDER unless SPARSEMEM.
536 page_cgroup_init_flatmem();
537 mem_init();
538 kmem_cache_init();
539 percpu_init_late();
540 pgtable_cache_init();
541 vmalloc_init();
544 asmlinkage void __init start_kernel(void)
546 char * command_line;
547 extern const struct kernel_param __start___param[], __stop___param[];
549 smp_setup_processor_id();
552 * Need to run as early as possible, to initialize the
553 * lockdep hash:
555 lockdep_init();
556 debug_objects_early_init();
559 * Set up the the initial canary ASAP:
561 boot_init_stack_canary();
563 cgroup_init_early();
565 local_irq_disable();
566 early_boot_irqs_disabled = true;
569 * Interrupts are still disabled. Do necessary setups, then
570 * enable them
572 tick_init();
573 boot_cpu_init();
574 page_address_init();
575 printk(KERN_NOTICE "%s", linux_banner);
576 setup_arch(&command_line);
577 mm_init_owner(&init_mm, &init_task);
578 setup_command_line(command_line);
579 setup_nr_cpu_ids();
580 setup_per_cpu_areas();
581 smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
583 build_all_zonelists(NULL);
584 page_alloc_init();
586 printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
587 parse_early_param();
588 parse_args("Booting kernel", static_command_line, __start___param,
589 __stop___param - __start___param,
590 &unknown_bootoption);
592 * These use large bootmem allocations and must precede
593 * kmem_cache_init()
595 pidhash_init();
596 vfs_caches_init_early();
597 sort_main_extable();
598 trap_init();
599 mm_init();
601 * Set up the scheduler prior starting any interrupts (such as the
602 * timer interrupt). Full topology setup happens at smp_init()
603 * time - but meanwhile we still have a functioning scheduler.
605 sched_init();
607 * Disable preemption - early bootup scheduling is extremely
608 * fragile until we cpu_idle() for the first time.
610 preempt_disable();
611 if (!irqs_disabled()) {
612 printk(KERN_WARNING "start_kernel(): bug: interrupts were "
613 "enabled *very* early, fixing it\n");
614 local_irq_disable();
616 idr_init_cache();
617 perf_event_init();
618 rcu_init();
619 radix_tree_init();
620 /* init some links before init_ISA_irqs() */
621 early_irq_init();
622 init_IRQ();
623 prio_tree_init();
624 init_timers();
625 hrtimers_init();
626 softirq_init();
627 timekeeping_init();
628 time_init();
629 profile_init();
630 if (!irqs_disabled())
631 printk(KERN_CRIT "start_kernel(): bug: interrupts were "
632 "enabled early\n");
633 early_boot_irqs_disabled = false;
634 local_irq_enable();
636 /* Interrupts are enabled now so all GFP allocations are safe. */
637 gfp_allowed_mask = __GFP_BITS_MASK;
639 kmem_cache_init_late();
642 * HACK ALERT! This is early. We're enabling the console before
643 * we've done PCI setups etc, and console_init() must be aware of
644 * this. But we do want output early, in case something goes wrong.
646 console_init();
647 if (panic_later)
648 panic(panic_later, panic_param);
650 lockdep_info();
653 * Need to run this when irqs are enabled, because it wants
654 * to self-test [hard/soft]-irqs on/off lock inversion bugs
655 * too:
657 locking_selftest();
659 #ifdef CONFIG_BLK_DEV_INITRD
660 if (initrd_start && !initrd_below_start_ok &&
661 page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
662 printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
663 "disabling it.\n",
664 page_to_pfn(virt_to_page((void *)initrd_start)),
665 min_low_pfn);
666 initrd_start = 0;
668 #endif
669 page_cgroup_init();
670 enable_debug_pagealloc();
671 kmemleak_init();
672 debug_objects_mem_init();
673 setup_per_cpu_pageset();
674 numa_policy_init();
675 if (late_time_init)
676 late_time_init();
677 sched_clock_init();
678 calibrate_delay();
679 pidmap_init();
680 anon_vma_init();
681 #ifdef CONFIG_X86
682 if (efi_enabled)
683 efi_enter_virtual_mode();
684 #endif
685 thread_info_cache_init();
686 cred_init();
687 fork_init(totalram_pages);
688 proc_caches_init();
689 buffer_init();
690 key_init();
691 security_init();
692 dbg_late_init();
693 vfs_caches_init(totalram_pages);
694 signals_init();
695 /* rootfs populating might need page-writeback */
696 page_writeback_init();
697 #ifdef CONFIG_PROC_FS
698 proc_root_init();
699 #endif
700 cgroup_init();
701 cpuset_init();
702 taskstats_init_early();
703 delayacct_init();
705 check_bugs();
707 acpi_early_init(); /* before LAPIC and SMP init */
708 sfi_init_late();
710 ftrace_init();
712 /* Do the rest non-__init'ed, we're now alive */
713 rest_init();
716 /* Call all constructor functions linked into the kernel. */
717 static void __init do_ctors(void)
719 #ifdef CONFIG_CONSTRUCTORS
720 ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
722 for (; fn < (ctor_fn_t *) __ctors_end; fn++)
723 (*fn)();
724 #endif
727 int initcall_debug;
728 core_param(initcall_debug, initcall_debug, bool, 0644);
730 static char msgbuf[64];
732 static int __init_or_module do_one_initcall_debug(initcall_t fn)
734 ktime_t calltime, delta, rettime;
735 unsigned long long duration;
736 int ret;
738 printk(KERN_DEBUG "calling %pF @ %i\n", fn, task_pid_nr(current));
739 calltime = ktime_get();
740 ret = fn();
741 rettime = ktime_get();
742 delta = ktime_sub(rettime, calltime);
743 duration = (unsigned long long) ktime_to_ns(delta) >> 10;
744 printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n", fn,
745 ret, duration);
747 return ret;
750 int __init_or_module do_one_initcall(initcall_t fn)
752 int count = preempt_count();
753 int ret;
755 if (initcall_debug)
756 ret = do_one_initcall_debug(fn);
757 else
758 ret = fn();
760 msgbuf[0] = 0;
762 if (ret && ret != -ENODEV && initcall_debug)
763 sprintf(msgbuf, "error code %d ", ret);
765 if (preempt_count() != count) {
766 strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
767 preempt_count() = count;
769 if (irqs_disabled()) {
770 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
771 local_irq_enable();
773 if (msgbuf[0]) {
774 printk("initcall %pF returned with %s\n", fn, msgbuf);
777 return ret;
781 extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
783 static void __init do_initcalls(void)
785 initcall_t *fn;
787 for (fn = __early_initcall_end; fn < __initcall_end; fn++)
788 do_one_initcall(*fn);
792 * Ok, the machine is now initialized. None of the devices
793 * have been touched yet, but the CPU subsystem is up and
794 * running, and memory and process management works.
796 * Now we can finally start doing some real work..
798 static void __init do_basic_setup(void)
800 cpuset_init_smp();
801 usermodehelper_init();
802 init_tmpfs();
803 driver_init();
804 init_irq_proc();
805 do_ctors();
806 do_initcalls();
809 static void __init do_pre_smp_initcalls(void)
811 initcall_t *fn;
813 for (fn = __initcall_start; fn < __early_initcall_end; fn++)
814 do_one_initcall(*fn);
817 static void run_init_process(const char *init_filename)
819 argv_init[0] = init_filename;
820 kernel_execve(init_filename, argv_init, envp_init);
823 /* This is a non __init function. Force it to be noinline otherwise gcc
824 * makes it inline to init() and it becomes part of init.text section
826 static noinline int init_post(void)
828 /* need to finish all async __init code before freeing the memory */
829 async_synchronize_full();
830 free_initmem();
831 mark_rodata_ro();
832 system_state = SYSTEM_RUNNING;
833 numa_default_policy();
836 current->signal->flags |= SIGNAL_UNKILLABLE;
838 if (ramdisk_execute_command) {
839 run_init_process(ramdisk_execute_command);
840 printk(KERN_WARNING "Failed to execute %s\n",
841 ramdisk_execute_command);
845 * We try each of these until one succeeds.
847 * The Bourne shell can be used instead of init if we are
848 * trying to recover a really broken machine.
850 if (execute_command) {
851 run_init_process(execute_command);
852 printk(KERN_WARNING "Failed to execute %s. Attempting "
853 "defaults...\n", execute_command);
855 run_init_process("/sbin/init");
856 run_init_process("/etc/init");
857 run_init_process("/bin/init");
858 run_init_process("/bin/sh");
860 panic("No init found. Try passing init= option to kernel. "
861 "See Linux Documentation/init.txt for guidance.");
864 static int __init kernel_init(void * unused)
867 * Wait until kthreadd is all set-up.
869 wait_for_completion(&kthreadd_done);
871 * init can allocate pages on any node
873 set_mems_allowed(node_states[N_HIGH_MEMORY]);
875 * init can run on any cpu.
877 set_cpus_allowed_ptr(current, cpu_all_mask);
879 * Tell the world that we're going to be the grim
880 * reaper of innocent orphaned children.
882 * We don't want people to have to make incorrect
883 * assumptions about where in the task array this
884 * can be found.
886 init_pid_ns.child_reaper = current;
888 cad_pid = task_pid(current);
890 smp_prepare_cpus(setup_max_cpus);
892 do_pre_smp_initcalls();
893 lockup_detector_init();
895 smp_init();
896 sched_init_smp();
898 do_basic_setup();
900 /* Open the /dev/console on the rootfs, this should never fail */
901 if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
902 printk(KERN_WARNING "Warning: unable to open an initial console.\n");
904 (void) sys_dup(0);
905 (void) sys_dup(0);
907 * check if there is an early userspace init. If yes, let it do all
908 * the work
911 if (!ramdisk_execute_command)
912 ramdisk_execute_command = "/init";
914 if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
915 ramdisk_execute_command = NULL;
916 prepare_namespace();
920 * Ok, we have completed the initial bootup, and
921 * we're essentially up and running. Get rid of the
922 * initmem segments and start the user-mode stuff..
925 init_post();
926 return 0;