Root/init/main.c

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 <grif@acm.org>
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/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/smp_lock.h>
24#include <linux/initrd.h>
25#include <linux/bootmem.h>
26#include <linux/acpi.h>
27#include <linux/tty.h>
28#include <linux/percpu.h>
29#include <linux/kmod.h>
30#include <linux/vmalloc.h>
31#include <linux/kernel_stat.h>
32#include <linux/start_kernel.h>
33#include <linux/security.h>
34#include <linux/smp.h>
35#include <linux/workqueue.h>
36#include <linux/profile.h>
37#include <linux/rcupdate.h>
38#include <linux/moduleparam.h>
39#include <linux/kallsyms.h>
40#include <linux/writeback.h>
41#include <linux/cpu.h>
42#include <linux/cpuset.h>
43#include <linux/cgroup.h>
44#include <linux/efi.h>
45#include <linux/tick.h>
46#include <linux/interrupt.h>
47#include <linux/taskstats_kern.h>
48#include <linux/delayacct.h>
49#include <linux/unistd.h>
50#include <linux/rmap.h>
51#include <linux/mempolicy.h>
52#include <linux/key.h>
53#include <linux/buffer_head.h>
54#include <linux/page_cgroup.h>
55#include <linux/debug_locks.h>
56#include <linux/debugobjects.h>
57#include <linux/lockdep.h>
58#include <linux/kmemleak.h>
59#include <linux/pid_namespace.h>
60#include <linux/device.h>
61#include <linux/kthread.h>
62#include <linux/sched.h>
63#include <linux/signal.h>
64#include <linux/idr.h>
65#include <linux/ftrace.h>
66#include <linux/async.h>
67#include <linux/kmemcheck.h>
68#include <linux/kmemtrace.h>
69#include <linux/sfi.h>
70#include <linux/shmem_fs.h>
71#include <linux/slab.h>
72#include <trace/boot.h>
73
74#include <asm/io.h>
75#include <asm/bugs.h>
76#include <asm/setup.h>
77#include <asm/sections.h>
78#include <asm/cacheflush.h>
79
80#ifdef CONFIG_X86_LOCAL_APIC
81#include <asm/smp.h>
82#endif
83
84static int kernel_init(void *);
85
86extern void init_IRQ(void);
87extern void fork_init(unsigned long);
88extern void mca_init(void);
89extern void sbus_init(void);
90extern void prio_tree_init(void);
91extern void radix_tree_init(void);
92extern void free_initmem(void);
93#ifndef CONFIG_DEBUG_RODATA
94static inline void mark_rodata_ro(void) { }
95#endif
96
97#ifdef CONFIG_TC
98extern void tc_init(void);
99#endif
100
101enum system_states system_state __read_mostly;
102EXPORT_SYMBOL(system_state);
103
104/*
105 * Boot command-line arguments
106 */
107#define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
108#define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
109
110extern void time_init(void);
111/* Default late time init is NULL. archs can override this later. */
112void (*__initdata late_time_init)(void);
113extern void softirq_init(void);
114
115/* Untouched command line saved by arch-specific code. */
116char __initdata boot_command_line[COMMAND_LINE_SIZE];
117/* Untouched saved command line (eg. for /proc) */
118char *saved_command_line;
119/* Command line for parameter parsing */
120static char *static_command_line;
121
122static char *execute_command;
123static char *ramdisk_execute_command;
124
125#ifdef CONFIG_SMP
126/* Setup configured maximum number of CPUs to activate */
127unsigned int __initdata setup_max_cpus = NR_CPUS;
128
129/*
130 * Setup routine for controlling SMP activation
131 *
132 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
133 * activation entirely (the MPS table probe still happens, though).
134 *
135 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
136 * greater than 0, limits the maximum number of CPUs activated in
137 * SMP mode to <NUM>.
138 */
139
140void __weak arch_disable_smp_support(void) { }
141
142static int __init nosmp(char *str)
143{
144    setup_max_cpus = 0;
145    arch_disable_smp_support();
146
147    return 0;
148}
149
150early_param("nosmp", nosmp);
151
152/* this is hard limit */
153static int __init nrcpus(char *str)
154{
155    int nr_cpus;
156
157    get_option(&str, &nr_cpus);
158    if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
159        nr_cpu_ids = nr_cpus;
160
161    return 0;
162}
163
164early_param("nr_cpus", nrcpus);
165
166static int __init maxcpus(char *str)
167{
168    get_option(&str, &setup_max_cpus);
169    if (setup_max_cpus == 0)
170        arch_disable_smp_support();
171
172    return 0;
173}
174
175early_param("maxcpus", maxcpus);
176#else
177static const unsigned int setup_max_cpus = NR_CPUS;
178#endif
179
180/*
181 * If set, this is an indication to the drivers that reset the underlying
182 * device before going ahead with the initialization otherwise driver might
183 * rely on the BIOS and skip the reset operation.
184 *
185 * This is useful if kernel is booting in an unreliable environment.
186 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
187 * skipped and devices will be in unknown state.
188 */
189unsigned int reset_devices;
190EXPORT_SYMBOL(reset_devices);
191
192static int __init set_reset_devices(char *str)
193{
194    reset_devices = 1;
195    return 1;
196}
197
198__setup("reset_devices", set_reset_devices);
199
200static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
201char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
202static const char *panic_later, *panic_param;
203
204extern struct obs_kernel_param __setup_start[], __setup_end[];
205
206static int __init obsolete_checksetup(char *line)
207{
208    struct obs_kernel_param *p;
209    int had_early_param = 0;
210
211    p = __setup_start;
212    do {
213        int n = strlen(p->str);
214        if (!strncmp(line, p->str, n)) {
215            if (p->early) {
216                /* Already done in parse_early_param?
217                 * (Needs exact match on param part).
218                 * Keep iterating, as we can have early
219                 * params and __setups of same names 8( */
220                if (line[n] == '\0' || line[n] == '=')
221                    had_early_param = 1;
222            } else if (!p->setup_func) {
223                printk(KERN_WARNING "Parameter %s is obsolete,"
224                       " ignored\n", p->str);
225                return 1;
226            } else if (p->setup_func(line + n))
227                return 1;
228        }
229        p++;
230    } while (p < __setup_end);
231
232    return had_early_param;
233}
234
235/*
236 * This should be approx 2 Bo*oMips to start (note initial shift), and will
237 * still work even if initially too large, it will just take slightly longer
238 */
239unsigned long loops_per_jiffy = (1<<12);
240
241EXPORT_SYMBOL(loops_per_jiffy);
242
243static int __init debug_kernel(char *str)
244{
245    console_loglevel = 10;
246    return 0;
247}
248
249static int __init quiet_kernel(char *str)
250{
251    console_loglevel = 4;
252    return 0;
253}
254
255early_param("debug", debug_kernel);
256early_param("quiet", quiet_kernel);
257
258static int __init loglevel(char *str)
259{
260    get_option(&str, &console_loglevel);
261    return 0;
262}
263
264early_param("loglevel", loglevel);
265
266/*
267 * Unknown boot options get handed to init, unless they look like
268 * unused parameters (modprobe will find them in /proc/cmdline).
269 */
270static int __init unknown_bootoption(char *param, char *val)
271{
272    /* Change NUL term back to "=", to make "param" the whole string. */
273    if (val) {
274        /* param=val or param="val"? */
275        if (val == param+strlen(param)+1)
276            val[-1] = '=';
277        else if (val == param+strlen(param)+2) {
278            val[-2] = '=';
279            memmove(val-1, val, strlen(val)+1);
280            val--;
281        } else
282            BUG();
283    }
284
285    /* Handle obsolete-style parameters */
286    if (obsolete_checksetup(param))
287        return 0;
288
289    /* Unused module parameter. */
290    if (strchr(param, '.') && (!val || strchr(param, '.') < val))
291        return 0;
292
293    if (panic_later)
294        return 0;
295
296    if (val) {
297        /* Environment option */
298        unsigned int i;
299        for (i = 0; envp_init[i]; i++) {
300            if (i == MAX_INIT_ENVS) {
301                panic_later = "Too many boot env vars at `%s'";
302                panic_param = param;
303            }
304            if (!strncmp(param, envp_init[i], val - param))
305                break;
306        }
307        envp_init[i] = param;
308    } else {
309        /* Command line option */
310        unsigned int i;
311        for (i = 0; argv_init[i]; i++) {
312            if (i == MAX_INIT_ARGS) {
313                panic_later = "Too many boot init vars at `%s'";
314                panic_param = param;
315            }
316        }
317        argv_init[i] = param;
318    }
319    return 0;
320}
321
322#ifdef CONFIG_DEBUG_PAGEALLOC
323int __read_mostly debug_pagealloc_enabled = 0;
324#endif
325
326static int __init init_setup(char *str)
327{
328    unsigned int i;
329
330    execute_command = str;
331    /*
332     * In case LILO is going to boot us with default command line,
333     * it prepends "auto" before the whole cmdline which makes
334     * the shell think it should execute a script with such name.
335     * So we ignore all arguments entered _before_ init=... [MJ]
336     */
337    for (i = 1; i < MAX_INIT_ARGS; i++)
338        argv_init[i] = NULL;
339    return 1;
340}
341__setup("init=", init_setup);
342
343static int __init rdinit_setup(char *str)
344{
345    unsigned int i;
346
347    ramdisk_execute_command = str;
348    /* See "auto" comment in init_setup */
349    for (i = 1; i < MAX_INIT_ARGS; i++)
350        argv_init[i] = NULL;
351    return 1;
352}
353__setup("rdinit=", rdinit_setup);
354
355#ifndef CONFIG_SMP
356
357#ifdef CONFIG_X86_LOCAL_APIC
358static void __init smp_init(void)
359{
360    APIC_init_uniprocessor();
361}
362#else
363#define smp_init() do { } while (0)
364#endif
365
366static inline void setup_nr_cpu_ids(void) { }
367static inline void smp_prepare_cpus(unsigned int maxcpus) { }
368
369#else
370
371/* Setup number of possible processor ids */
372int nr_cpu_ids __read_mostly = NR_CPUS;
373EXPORT_SYMBOL(nr_cpu_ids);
374
375/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
376static void __init setup_nr_cpu_ids(void)
377{
378    nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
379}
380
381/* Called by boot processor to activate the rest. */
382static void __init smp_init(void)
383{
384    unsigned int cpu;
385
386    /* FIXME: This should be done in userspace --RR */
387    for_each_present_cpu(cpu) {
388        if (num_online_cpus() >= setup_max_cpus)
389            break;
390        if (!cpu_online(cpu))
391            cpu_up(cpu);
392    }
393
394    /* Any cleanup work */
395    printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
396    smp_cpus_done(setup_max_cpus);
397}
398
399#endif
400
401/*
402 * We need to store the untouched command line for future reference.
403 * We also need to store the touched command line since the parameter
404 * parsing is performed in place, and we should allow a component to
405 * store reference of name/value for future reference.
406 */
407static void __init setup_command_line(char *command_line)
408{
409    saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
410    static_command_line = alloc_bootmem(strlen (command_line)+1);
411    strcpy (saved_command_line, boot_command_line);
412    strcpy (static_command_line, command_line);
413}
414
415/*
416 * We need to finalize in a non-__init function or else race conditions
417 * between the root thread and the init thread may cause start_kernel to
418 * be reaped by free_initmem before the root thread has proceeded to
419 * cpu_idle.
420 *
421 * gcc-3.4 accidentally inlines this function, so use noinline.
422 */
423
424static noinline void __init_refok rest_init(void)
425    __releases(kernel_lock)
426{
427    int pid;
428
429    rcu_scheduler_starting();
430    kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
431    numa_default_policy();
432    pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
433    rcu_read_lock();
434    kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
435    rcu_read_unlock();
436    unlock_kernel();
437
438    /*
439     * The boot idle thread must execute schedule()
440     * at least once to get things moving:
441     */
442    init_idle_bootup_task(current);
443    preempt_enable_no_resched();
444    schedule();
445    preempt_disable();
446
447    /* Call into cpu_idle with preempt disabled */
448    cpu_idle();
449}
450
451/* Check for early params. */
452static int __init do_early_param(char *param, char *val)
453{
454    struct obs_kernel_param *p;
455
456    for (p = __setup_start; p < __setup_end; p++) {
457        if ((p->early && strcmp(param, p->str) == 0) ||
458            (strcmp(param, "console") == 0 &&
459             strcmp(p->str, "earlycon") == 0)
460        ) {
461            if (p->setup_func(val) != 0)
462                printk(KERN_WARNING
463                       "Malformed early option '%s'\n", param);
464        }
465    }
466    /* We accept everything at this stage. */
467    return 0;
468}
469
470void __init parse_early_options(char *cmdline)
471{
472    parse_args("early options", cmdline, NULL, 0, do_early_param);
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_early_options(tmp_cmdline);
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    set_cpu_online(cpu, true);
499    set_cpu_active(cpu, true);
500    set_cpu_present(cpu, true);
501    set_cpu_possible(cpu, true);
502}
503
504void __init __weak smp_setup_processor_id(void)
505{
506}
507
508void __init __weak thread_info_cache_init(void)
509{
510}
511
512/*
513 * Set up kernel memory allocators
514 */
515static void __init mm_init(void)
516{
517    /*
518     * page_cgroup requires countinous pages as memmap
519     * and it's bigger than MAX_ORDER unless SPARSEMEM.
520     */
521    page_cgroup_init_flatmem();
522    mem_init();
523    kmem_cache_init();
524    pgtable_cache_init();
525    vmalloc_init();
526}
527
528asmlinkage void __init start_kernel(void)
529{
530    char * command_line;
531    extern struct kernel_param __start___param[], __stop___param[];
532
533    smp_setup_processor_id();
534
535    /*
536     * Need to run as early as possible, to initialize the
537     * lockdep hash:
538     */
539    lockdep_init();
540    debug_objects_early_init();
541
542    /*
543     * Set up the the initial canary ASAP:
544     */
545    boot_init_stack_canary();
546
547    cgroup_init_early();
548
549    local_irq_disable();
550    early_boot_irqs_off();
551    early_init_irq_lock_class();
552
553/*
554 * Interrupts are still disabled. Do necessary setups, then
555 * enable them
556 */
557    lock_kernel();
558    tick_init();
559    boot_cpu_init();
560    page_address_init();
561    printk(KERN_NOTICE "%s", linux_banner);
562    setup_arch(&command_line);
563    mm_init_owner(&init_mm, &init_task);
564    setup_command_line(command_line);
565    setup_nr_cpu_ids();
566    setup_per_cpu_areas();
567    smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
568
569    build_all_zonelists();
570    page_alloc_init();
571
572    printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
573    parse_early_param();
574    parse_args("Booting kernel", static_command_line, __start___param,
575           __stop___param - __start___param,
576           &unknown_bootoption);
577    /*
578     * These use large bootmem allocations and must precede
579     * kmem_cache_init()
580     */
581    pidhash_init();
582    vfs_caches_init_early();
583    sort_main_extable();
584    trap_init();
585    mm_init();
586    /*
587     * Set up the scheduler prior starting any interrupts (such as the
588     * timer interrupt). Full topology setup happens at smp_init()
589     * time - but meanwhile we still have a functioning scheduler.
590     */
591    sched_init();
592    /*
593     * Disable preemption - early bootup scheduling is extremely
594     * fragile until we cpu_idle() for the first time.
595     */
596    preempt_disable();
597    if (!irqs_disabled()) {
598        printk(KERN_WARNING "start_kernel(): bug: interrupts were "
599                "enabled *very* early, fixing it\n");
600        local_irq_disable();
601    }
602    rcu_init();
603    radix_tree_init();
604    /* init some links before init_ISA_irqs() */
605    early_irq_init();
606    init_IRQ();
607    prio_tree_init();
608    init_timers();
609    hrtimers_init();
610    softirq_init();
611    timekeeping_init();
612    time_init();
613    profile_init();
614    if (!irqs_disabled())
615        printk(KERN_CRIT "start_kernel(): bug: interrupts were "
616                 "enabled early\n");
617    early_boot_irqs_on();
618    local_irq_enable();
619
620    /* Interrupts are enabled now so all GFP allocations are safe. */
621    gfp_allowed_mask = __GFP_BITS_MASK;
622
623    kmem_cache_init_late();
624
625    /*
626     * HACK ALERT! This is early. We're enabling the console before
627     * we've done PCI setups etc, and console_init() must be aware of
628     * this. But we do want output early, in case something goes wrong.
629     */
630    console_init();
631    if (panic_later)
632        panic(panic_later, panic_param);
633
634    lockdep_info();
635
636    /*
637     * Need to run this when irqs are enabled, because it wants
638     * to self-test [hard/soft]-irqs on/off lock inversion bugs
639     * too:
640     */
641    locking_selftest();
642
643#ifdef CONFIG_BLK_DEV_INITRD
644    if (initrd_start && !initrd_below_start_ok &&
645        page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
646        printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
647            "disabling it.\n",
648            page_to_pfn(virt_to_page((void *)initrd_start)),
649            min_low_pfn);
650        initrd_start = 0;
651    }
652#endif
653    page_cgroup_init();
654    enable_debug_pagealloc();
655    kmemtrace_init();
656    kmemleak_init();
657    debug_objects_mem_init();
658    idr_init_cache();
659    setup_per_cpu_pageset();
660    numa_policy_init();
661    if (late_time_init)
662        late_time_init();
663    sched_clock_init();
664    calibrate_delay();
665    pidmap_init();
666    anon_vma_init();
667#ifdef CONFIG_X86
668    if (efi_enabled)
669        efi_enter_virtual_mode();
670#endif
671    thread_info_cache_init();
672    cred_init();
673    fork_init(totalram_pages);
674    proc_caches_init();
675    buffer_init();
676    key_init();
677    security_init();
678    vfs_caches_init(totalram_pages);
679    signals_init();
680    /* rootfs populating might need page-writeback */
681    page_writeback_init();
682#ifdef CONFIG_PROC_FS
683    proc_root_init();
684#endif
685    cgroup_init();
686    cpuset_init();
687    taskstats_init_early();
688    delayacct_init();
689
690    check_bugs();
691
692    acpi_early_init(); /* before LAPIC and SMP init */
693    sfi_init_late();
694
695    ftrace_init();
696
697    /* Do the rest non-__init'ed, we're now alive */
698    rest_init();
699}
700
701/* Call all constructor functions linked into the kernel. */
702static void __init do_ctors(void)
703{
704#ifdef CONFIG_CONSTRUCTORS
705    ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
706
707    for (; fn < (ctor_fn_t *) __ctors_end; fn++)
708        (*fn)();
709#endif
710}
711
712int initcall_debug;
713core_param(initcall_debug, initcall_debug, bool, 0644);
714
715static char msgbuf[64];
716static struct boot_trace_call call;
717static struct boot_trace_ret ret;
718
719int do_one_initcall(initcall_t fn)
720{
721    int count = preempt_count();
722    ktime_t calltime, delta, rettime;
723
724    if (initcall_debug) {
725        call.caller = task_pid_nr(current);
726        printk("calling %pF @ %i\n", fn, call.caller);
727        calltime = ktime_get();
728        trace_boot_call(&call, fn);
729        enable_boot_trace();
730    }
731
732    ret.result = fn();
733
734    if (initcall_debug) {
735        disable_boot_trace();
736        rettime = ktime_get();
737        delta = ktime_sub(rettime, calltime);
738        ret.duration = (unsigned long long) ktime_to_ns(delta) >> 10;
739        trace_boot_ret(&ret, fn);
740        printk("initcall %pF returned %d after %Ld usecs\n", fn,
741            ret.result, ret.duration);
742    }
743
744    msgbuf[0] = 0;
745
746    if (ret.result && ret.result != -ENODEV && initcall_debug)
747        sprintf(msgbuf, "error code %d ", ret.result);
748
749    if (preempt_count() != count) {
750        strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
751        preempt_count() = count;
752    }
753    if (irqs_disabled()) {
754        strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
755        local_irq_enable();
756    }
757    if (msgbuf[0]) {
758        printk("initcall %pF returned with %s\n", fn, msgbuf);
759    }
760
761    return ret.result;
762}
763
764
765extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
766
767static void __init do_initcalls(void)
768{
769    initcall_t *fn;
770
771    for (fn = __early_initcall_end; fn < __initcall_end; fn++)
772        do_one_initcall(*fn);
773
774    /* Make sure there is no pending stuff from the initcall sequence */
775    flush_scheduled_work();
776}
777
778/*
779 * Ok, the machine is now initialized. None of the devices
780 * have been touched yet, but the CPU subsystem is up and
781 * running, and memory and process management works.
782 *
783 * Now we can finally start doing some real work..
784 */
785static void __init do_basic_setup(void)
786{
787    init_workqueues();
788    cpuset_init_smp();
789    usermodehelper_init();
790    init_tmpfs();
791    driver_init();
792    init_irq_proc();
793    do_ctors();
794    do_initcalls();
795}
796
797static void __init do_pre_smp_initcalls(void)
798{
799    initcall_t *fn;
800
801    for (fn = __initcall_start; fn < __early_initcall_end; fn++)
802        do_one_initcall(*fn);
803}
804
805static void run_init_process(char *init_filename)
806{
807    argv_init[0] = init_filename;
808    kernel_execve(init_filename, argv_init, envp_init);
809}
810
811/* This is a non __init function. Force it to be noinline otherwise gcc
812 * makes it inline to init() and it becomes part of init.text section
813 */
814static noinline int init_post(void)
815    __releases(kernel_lock)
816{
817    /* need to finish all async __init code before freeing the memory */
818    async_synchronize_full();
819    free_initmem();
820    unlock_kernel();
821    mark_rodata_ro();
822    system_state = SYSTEM_RUNNING;
823    numa_default_policy();
824
825
826    current->signal->flags |= SIGNAL_UNKILLABLE;
827
828    if (ramdisk_execute_command) {
829        run_init_process(ramdisk_execute_command);
830        printk(KERN_WARNING "Failed to execute %s\n",
831                ramdisk_execute_command);
832    }
833
834    /*
835     * We try each of these until one succeeds.
836     *
837     * The Bourne shell can be used instead of init if we are
838     * trying to recover a really broken machine.
839     */
840    if (execute_command) {
841        run_init_process(execute_command);
842        printk(KERN_WARNING "Failed to execute %s. Attempting "
843                    "defaults...\n", execute_command);
844    }
845    run_init_process("/sbin/init");
846    run_init_process("/etc/init");
847    run_init_process("/bin/init");
848    run_init_process("/bin/sh");
849
850    panic("No init found. Try passing init= option to kernel. "
851          "See Linux Documentation/init.txt for guidance.");
852}
853
854static int __init kernel_init(void * unused)
855{
856    lock_kernel();
857
858    /*
859     * init can allocate pages on any node
860     */
861    set_mems_allowed(node_states[N_HIGH_MEMORY]);
862    /*
863     * init can run on any cpu.
864     */
865    set_cpus_allowed_ptr(current, cpu_all_mask);
866    /*
867     * Tell the world that we're going to be the grim
868     * reaper of innocent orphaned children.
869     *
870     * We don't want people to have to make incorrect
871     * assumptions about where in the task array this
872     * can be found.
873     */
874    init_pid_ns.child_reaper = current;
875
876    cad_pid = task_pid(current);
877
878    smp_prepare_cpus(setup_max_cpus);
879
880    do_pre_smp_initcalls();
881    start_boot_trace();
882
883    smp_init();
884    sched_init_smp();
885
886    do_basic_setup();
887
888    /* Open the /dev/console on the rootfs, this should never fail */
889    if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
890        printk(KERN_WARNING "Warning: unable to open an initial console.\n");
891
892    (void) sys_dup(0);
893    (void) sys_dup(0);
894    /*
895     * check if there is an early userspace init. If yes, let it do all
896     * the work
897     */
898
899    if (!ramdisk_execute_command)
900        ramdisk_execute_command = "/init";
901
902    if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
903        ramdisk_execute_command = NULL;
904        prepare_namespace();
905    }
906
907    /*
908     * Ok, we have completed the initial bootup, and
909     * we're essentially up and running. Get rid of the
910     * initmem segments and start the user-mode stuff..
911     */
912
913    init_post();
914    return 0;
915}
916

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