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/gfp.h>
29#include <linux/percpu.h>
30#include <linux/kmod.h>
31#include <linux/vmalloc.h>
32#include <linux/kernel_stat.h>
33#include <linux/start_kernel.h>
34#include <linux/security.h>
35#include <linux/smp.h>
36#include <linux/workqueue.h>
37#include <linux/profile.h>
38#include <linux/rcupdate.h>
39#include <linux/moduleparam.h>
40#include <linux/kallsyms.h>
41#include <linux/writeback.h>
42#include <linux/cpu.h>
43#include <linux/cpuset.h>
44#include <linux/cgroup.h>
45#include <linux/efi.h>
46#include <linux/tick.h>
47#include <linux/interrupt.h>
48#include <linux/taskstats_kern.h>
49#include <linux/delayacct.h>
50#include <linux/unistd.h>
51#include <linux/rmap.h>
52#include <linux/mempolicy.h>
53#include <linux/key.h>
54#include <linux/buffer_head.h>
55#include <linux/page_cgroup.h>
56#include <linux/debug_locks.h>
57#include <linux/debugobjects.h>
58#include <linux/lockdep.h>
59#include <linux/kmemleak.h>
60#include <linux/pid_namespace.h>
61#include <linux/device.h>
62#include <linux/kthread.h>
63#include <linux/sched.h>
64#include <linux/signal.h>
65#include <linux/idr.h>
66#include <linux/ftrace.h>
67#include <linux/async.h>
68#include <linux/kmemcheck.h>
69#include <linux/kmemtrace.h>
70#include <linux/sfi.h>
71#include <linux/shmem_fs.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
152static int __init maxcpus(char *str)
153{
154    get_option(&str, &setup_max_cpus);
155    if (setup_max_cpus == 0)
156        arch_disable_smp_support();
157
158    return 0;
159}
160
161early_param("maxcpus", maxcpus);
162#else
163const unsigned int setup_max_cpus = NR_CPUS;
164#endif
165
166/*
167 * If set, this is an indication to the drivers that reset the underlying
168 * device before going ahead with the initialization otherwise driver might
169 * rely on the BIOS and skip the reset operation.
170 *
171 * This is useful if kernel is booting in an unreliable environment.
172 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
173 * skipped and devices will be in unknown state.
174 */
175unsigned int reset_devices;
176EXPORT_SYMBOL(reset_devices);
177
178static int __init set_reset_devices(char *str)
179{
180    reset_devices = 1;
181    return 1;
182}
183
184__setup("reset_devices", set_reset_devices);
185
186static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
187char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
188static const char *panic_later, *panic_param;
189
190extern struct obs_kernel_param __setup_start[], __setup_end[];
191
192static int __init obsolete_checksetup(char *line)
193{
194    struct obs_kernel_param *p;
195    int had_early_param = 0;
196
197    p = __setup_start;
198    do {
199        int n = strlen(p->str);
200        if (!strncmp(line, p->str, n)) {
201            if (p->early) {
202                /* Already done in parse_early_param?
203                 * (Needs exact match on param part).
204                 * Keep iterating, as we can have early
205                 * params and __setups of same names 8( */
206                if (line[n] == '\0' || line[n] == '=')
207                    had_early_param = 1;
208            } else if (!p->setup_func) {
209                printk(KERN_WARNING "Parameter %s is obsolete,"
210                       " ignored\n", p->str);
211                return 1;
212            } else if (p->setup_func(line + n))
213                return 1;
214        }
215        p++;
216    } while (p < __setup_end);
217
218    return had_early_param;
219}
220
221/*
222 * This should be approx 2 Bo*oMips to start (note initial shift), and will
223 * still work even if initially too large, it will just take slightly longer
224 */
225unsigned long loops_per_jiffy = (1<<12);
226
227EXPORT_SYMBOL(loops_per_jiffy);
228
229static int __init debug_kernel(char *str)
230{
231    console_loglevel = 10;
232    return 0;
233}
234
235static int __init quiet_kernel(char *str)
236{
237    console_loglevel = 4;
238    return 0;
239}
240
241early_param("debug", debug_kernel);
242early_param("quiet", quiet_kernel);
243
244static int __init loglevel(char *str)
245{
246    get_option(&str, &console_loglevel);
247    return 0;
248}
249
250early_param("loglevel", loglevel);
251
252/*
253 * Unknown boot options get handed to init, unless they look like
254 * unused parameters (modprobe will find them in /proc/cmdline).
255 */
256static int __init unknown_bootoption(char *param, char *val)
257{
258    /* Change NUL term back to "=", to make "param" the whole string. */
259    if (val) {
260        /* param=val or param="val"? */
261        if (val == param+strlen(param)+1)
262            val[-1] = '=';
263        else if (val == param+strlen(param)+2) {
264            val[-2] = '=';
265            memmove(val-1, val, strlen(val)+1);
266            val--;
267        } else
268            BUG();
269    }
270
271    /* Handle obsolete-style parameters */
272    if (obsolete_checksetup(param))
273        return 0;
274
275    /* Unused module parameter. */
276    if (strchr(param, '.') && (!val || strchr(param, '.') < val))
277        return 0;
278
279    if (panic_later)
280        return 0;
281
282    if (val) {
283        /* Environment option */
284        unsigned int i;
285        for (i = 0; envp_init[i]; i++) {
286            if (i == MAX_INIT_ENVS) {
287                panic_later = "Too many boot env vars at `%s'";
288                panic_param = param;
289            }
290            if (!strncmp(param, envp_init[i], val - param))
291                break;
292        }
293        envp_init[i] = param;
294    } else {
295        /* Command line option */
296        unsigned int i;
297        for (i = 0; argv_init[i]; i++) {
298            if (i == MAX_INIT_ARGS) {
299                panic_later = "Too many boot init vars at `%s'";
300                panic_param = param;
301            }
302        }
303        argv_init[i] = param;
304    }
305    return 0;
306}
307
308#ifdef CONFIG_DEBUG_PAGEALLOC
309int __read_mostly debug_pagealloc_enabled = 0;
310#endif
311
312static int __init init_setup(char *str)
313{
314    unsigned int i;
315
316    execute_command = str;
317    /*
318     * In case LILO is going to boot us with default command line,
319     * it prepends "auto" before the whole cmdline which makes
320     * the shell think it should execute a script with such name.
321     * So we ignore all arguments entered _before_ init=... [MJ]
322     */
323    for (i = 1; i < MAX_INIT_ARGS; i++)
324        argv_init[i] = NULL;
325    return 1;
326}
327__setup("init=", init_setup);
328
329static int __init rdinit_setup(char *str)
330{
331    unsigned int i;
332
333    ramdisk_execute_command = str;
334    /* See "auto" comment in init_setup */
335    for (i = 1; i < MAX_INIT_ARGS; i++)
336        argv_init[i] = NULL;
337    return 1;
338}
339__setup("rdinit=", rdinit_setup);
340
341#ifndef CONFIG_SMP
342
343#ifdef CONFIG_X86_LOCAL_APIC
344static void __init smp_init(void)
345{
346    APIC_init_uniprocessor();
347}
348#else
349#define smp_init() do { } while (0)
350#endif
351
352static inline void setup_nr_cpu_ids(void) { }
353static inline void smp_prepare_cpus(unsigned int maxcpus) { }
354
355#else
356
357/* Setup number of possible processor ids */
358int nr_cpu_ids __read_mostly = NR_CPUS;
359EXPORT_SYMBOL(nr_cpu_ids);
360
361/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
362static void __init setup_nr_cpu_ids(void)
363{
364    nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
365}
366
367/* Called by boot processor to activate the rest. */
368static void __init smp_init(void)
369{
370    unsigned int cpu;
371
372    /*
373     * Set up the current CPU as possible to migrate to.
374     * The other ones will be done by cpu_up/cpu_down()
375     */
376    set_cpu_active(smp_processor_id(), true);
377
378    /* FIXME: This should be done in userspace --RR */
379    for_each_present_cpu(cpu) {
380        if (num_online_cpus() >= setup_max_cpus)
381            break;
382        if (!cpu_online(cpu))
383            cpu_up(cpu);
384    }
385
386    /* Any cleanup work */
387    printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
388    smp_cpus_done(setup_max_cpus);
389}
390
391#endif
392
393/*
394 * We need to store the untouched command line for future reference.
395 * We also need to store the touched command line since the parameter
396 * parsing is performed in place, and we should allow a component to
397 * store reference of name/value for future reference.
398 */
399static void __init setup_command_line(char *command_line)
400{
401    saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
402    static_command_line = alloc_bootmem(strlen (command_line)+1);
403    strcpy (saved_command_line, boot_command_line);
404    strcpy (static_command_line, command_line);
405}
406
407/*
408 * We need to finalize in a non-__init function or else race conditions
409 * between the root thread and the init thread may cause start_kernel to
410 * be reaped by free_initmem before the root thread has proceeded to
411 * cpu_idle.
412 *
413 * gcc-3.4 accidentally inlines this function, so use noinline.
414 */
415
416static noinline void __init_refok rest_init(void)
417    __releases(kernel_lock)
418{
419    int pid;
420
421    rcu_scheduler_starting();
422    kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
423    numa_default_policy();
424    pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
425    kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
426    unlock_kernel();
427
428    /*
429     * The boot idle thread must execute schedule()
430     * at least once to get things moving:
431     */
432    init_idle_bootup_task(current);
433    preempt_enable_no_resched();
434    schedule();
435    preempt_disable();
436
437    /* Call into cpu_idle with preempt disabled */
438    cpu_idle();
439}
440
441/* Check for early params. */
442static int __init do_early_param(char *param, char *val)
443{
444    struct obs_kernel_param *p;
445
446    for (p = __setup_start; p < __setup_end; p++) {
447        if ((p->early && strcmp(param, p->str) == 0) ||
448            (strcmp(param, "console") == 0 &&
449             strcmp(p->str, "earlycon") == 0)
450        ) {
451            if (p->setup_func(val) != 0)
452                printk(KERN_WARNING
453                       "Malformed early option '%s'\n", param);
454        }
455    }
456    /* We accept everything at this stage. */
457    return 0;
458}
459
460void __init parse_early_options(char *cmdline)
461{
462    parse_args("early options", cmdline, NULL, 0, do_early_param);
463}
464
465/* Arch code calls this early on, or if not, just before other parsing. */
466void __init parse_early_param(void)
467{
468    static __initdata int done = 0;
469    static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
470
471    if (done)
472        return;
473
474    /* All fall through to do_early_param. */
475    strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
476    parse_early_options(tmp_cmdline);
477    done = 1;
478}
479
480/*
481 * Activate the first processor.
482 */
483
484static void __init boot_cpu_init(void)
485{
486    int cpu = smp_processor_id();
487    /* Mark the boot cpu "present", "online" etc for SMP and UP case */
488    set_cpu_online(cpu, true);
489    set_cpu_present(cpu, true);
490    set_cpu_possible(cpu, true);
491}
492
493void __init __weak smp_setup_processor_id(void)
494{
495}
496
497void __init __weak thread_info_cache_init(void)
498{
499}
500
501/*
502 * Set up kernel memory allocators
503 */
504static void __init mm_init(void)
505{
506    /*
507     * page_cgroup requires countinous pages as memmap
508     * and it's bigger than MAX_ORDER unless SPARSEMEM.
509     */
510    page_cgroup_init_flatmem();
511    mem_init();
512    kmem_cache_init();
513    pgtable_cache_init();
514    vmalloc_init();
515}
516
517asmlinkage void __init start_kernel(void)
518{
519    char * command_line;
520    extern struct kernel_param __start___param[], __stop___param[];
521
522    smp_setup_processor_id();
523
524    /*
525     * Need to run as early as possible, to initialize the
526     * lockdep hash:
527     */
528    lockdep_init();
529    debug_objects_early_init();
530
531    /*
532     * Set up the the initial canary ASAP:
533     */
534    boot_init_stack_canary();
535
536    cgroup_init_early();
537
538    local_irq_disable();
539    early_boot_irqs_off();
540    early_init_irq_lock_class();
541
542/*
543 * Interrupts are still disabled. Do necessary setups, then
544 * enable them
545 */
546    lock_kernel();
547    tick_init();
548    boot_cpu_init();
549    page_address_init();
550    printk(KERN_NOTICE "%s", linux_banner);
551    setup_arch(&command_line);
552    mm_init_owner(&init_mm, &init_task);
553    setup_command_line(command_line);
554    setup_nr_cpu_ids();
555    setup_per_cpu_areas();
556    smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
557
558    build_all_zonelists();
559    page_alloc_init();
560
561    printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
562    parse_early_param();
563    parse_args("Booting kernel", static_command_line, __start___param,
564           __stop___param - __start___param,
565           &unknown_bootoption);
566    /*
567     * These use large bootmem allocations and must precede
568     * kmem_cache_init()
569     */
570    pidhash_init();
571    vfs_caches_init_early();
572    sort_main_extable();
573    trap_init();
574    mm_init();
575    /*
576     * Set up the scheduler prior starting any interrupts (such as the
577     * timer interrupt). Full topology setup happens at smp_init()
578     * time - but meanwhile we still have a functioning scheduler.
579     */
580    sched_init();
581    /*
582     * Disable preemption - early bootup scheduling is extremely
583     * fragile until we cpu_idle() for the first time.
584     */
585    preempt_disable();
586    if (!irqs_disabled()) {
587        printk(KERN_WARNING "start_kernel(): bug: interrupts were "
588                "enabled *very* early, fixing it\n");
589        local_irq_disable();
590    }
591    rcu_init();
592    /* init some links before init_ISA_irqs() */
593    early_irq_init();
594    init_IRQ();
595    prio_tree_init();
596    init_timers();
597    hrtimers_init();
598    softirq_init();
599    timekeeping_init();
600    time_init();
601    profile_init();
602    if (!irqs_disabled())
603        printk(KERN_CRIT "start_kernel(): bug: interrupts were "
604                 "enabled early\n");
605    early_boot_irqs_on();
606    local_irq_enable();
607
608    /* Interrupts are enabled now so all GFP allocations are safe. */
609    set_gfp_allowed_mask(__GFP_BITS_MASK);
610
611    kmem_cache_init_late();
612
613    /*
614     * HACK ALERT! This is early. We're enabling the console before
615     * we've done PCI setups etc, and console_init() must be aware of
616     * this. But we do want output early, in case something goes wrong.
617     */
618    console_init();
619    if (panic_later)
620        panic(panic_later, panic_param);
621
622    lockdep_info();
623
624    /*
625     * Need to run this when irqs are enabled, because it wants
626     * to self-test [hard/soft]-irqs on/off lock inversion bugs
627     * too:
628     */
629    locking_selftest();
630
631#ifdef CONFIG_BLK_DEV_INITRD
632    if (initrd_start && !initrd_below_start_ok &&
633        page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
634        printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
635            "disabling it.\n",
636            page_to_pfn(virt_to_page((void *)initrd_start)),
637            min_low_pfn);
638        initrd_start = 0;
639    }
640#endif
641    page_cgroup_init();
642    enable_debug_pagealloc();
643    kmemtrace_init();
644    kmemleak_init();
645    debug_objects_mem_init();
646    idr_init_cache();
647    setup_per_cpu_pageset();
648    numa_policy_init();
649    if (late_time_init)
650        late_time_init();
651    sched_clock_init();
652    calibrate_delay();
653    pidmap_init();
654    anon_vma_init();
655#ifdef CONFIG_X86
656    if (efi_enabled)
657        efi_enter_virtual_mode();
658#endif
659    thread_info_cache_init();
660    cred_init();
661    fork_init(totalram_pages);
662    proc_caches_init();
663    buffer_init();
664    key_init();
665    security_init();
666    vfs_caches_init(totalram_pages);
667    radix_tree_init();
668    signals_init();
669    /* rootfs populating might need page-writeback */
670    page_writeback_init();
671#ifdef CONFIG_PROC_FS
672    proc_root_init();
673#endif
674    cgroup_init();
675    cpuset_init();
676    taskstats_init_early();
677    delayacct_init();
678
679    check_bugs();
680
681    acpi_early_init(); /* before LAPIC and SMP init */
682    sfi_init_late();
683
684    ftrace_init();
685
686    /* Do the rest non-__init'ed, we're now alive */
687    rest_init();
688}
689
690/* Call all constructor functions linked into the kernel. */
691static void __init do_ctors(void)
692{
693#ifdef CONFIG_CONSTRUCTORS
694    ctor_fn_t *call = (ctor_fn_t *) __ctors_start;
695
696    for (; call < (ctor_fn_t *) __ctors_end; call++)
697        (*call)();
698#endif
699}
700
701int initcall_debug;
702core_param(initcall_debug, initcall_debug, bool, 0644);
703
704static char msgbuf[64];
705static struct boot_trace_call call;
706static struct boot_trace_ret ret;
707
708int do_one_initcall(initcall_t fn)
709{
710    int count = preempt_count();
711    ktime_t calltime, delta, rettime;
712
713    if (initcall_debug) {
714        call.caller = task_pid_nr(current);
715        printk("calling %pF @ %i\n", fn, call.caller);
716        calltime = ktime_get();
717        trace_boot_call(&call, fn);
718        enable_boot_trace();
719    }
720
721    ret.result = fn();
722
723    if (initcall_debug) {
724        disable_boot_trace();
725        rettime = ktime_get();
726        delta = ktime_sub(rettime, calltime);
727        ret.duration = (unsigned long long) ktime_to_ns(delta) >> 10;
728        trace_boot_ret(&ret, fn);
729        printk("initcall %pF returned %d after %Ld usecs\n", fn,
730            ret.result, ret.duration);
731    }
732
733    msgbuf[0] = 0;
734
735    if (ret.result && ret.result != -ENODEV && initcall_debug)
736        sprintf(msgbuf, "error code %d ", ret.result);
737
738    if (preempt_count() != count) {
739        strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
740        preempt_count() = count;
741    }
742    if (irqs_disabled()) {
743        strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
744        local_irq_enable();
745    }
746    if (msgbuf[0]) {
747        printk("initcall %pF returned with %s\n", fn, msgbuf);
748    }
749
750    return ret.result;
751}
752
753
754extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
755
756static void __init do_initcalls(void)
757{
758    initcall_t *call;
759
760    for (call = __early_initcall_end; call < __initcall_end; call++)
761        do_one_initcall(*call);
762
763    /* Make sure there is no pending stuff from the initcall sequence */
764    flush_scheduled_work();
765}
766
767/*
768 * Ok, the machine is now initialized. None of the devices
769 * have been touched yet, but the CPU subsystem is up and
770 * running, and memory and process management works.
771 *
772 * Now we can finally start doing some real work..
773 */
774static void __init do_basic_setup(void)
775{
776    init_workqueues();
777    cpuset_init_smp();
778    usermodehelper_init();
779    init_tmpfs();
780    driver_init();
781    init_irq_proc();
782    do_ctors();
783    do_initcalls();
784}
785
786static void __init do_pre_smp_initcalls(void)
787{
788    initcall_t *call;
789
790    for (call = __initcall_start; call < __early_initcall_end; call++)
791        do_one_initcall(*call);
792}
793
794static void run_init_process(char *init_filename)
795{
796    argv_init[0] = init_filename;
797    kernel_execve(init_filename, argv_init, envp_init);
798}
799
800/* This is a non __init function. Force it to be noinline otherwise gcc
801 * makes it inline to init() and it becomes part of init.text section
802 */
803static noinline int init_post(void)
804    __releases(kernel_lock)
805{
806    /* need to finish all async __init code before freeing the memory */
807    async_synchronize_full();
808    free_initmem();
809    unlock_kernel();
810    mark_rodata_ro();
811    system_state = SYSTEM_RUNNING;
812    numa_default_policy();
813
814    if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
815        printk(KERN_WARNING "Please be patient, while OpenWrt loads ...\n");
816
817    (void) sys_dup(0);
818    (void) sys_dup(0);
819
820    current->signal->flags |= SIGNAL_UNKILLABLE;
821
822    if (ramdisk_execute_command) {
823        run_init_process(ramdisk_execute_command);
824        printk(KERN_WARNING "Failed to execute %s\n",
825                ramdisk_execute_command);
826    }
827
828    /*
829     * We try each of these until one succeeds.
830     *
831     * The Bourne shell can be used instead of init if we are
832     * trying to recover a really broken machine.
833     */
834    if (execute_command) {
835        run_init_process(execute_command);
836        printk(KERN_WARNING "Failed to execute %s. Attempting "
837                    "defaults...\n", execute_command);
838    }
839    run_init_process("/etc/preinit");
840
841    panic("No init found. Try passing init= option to kernel.");
842}
843
844static int __init kernel_init(void * unused)
845{
846    lock_kernel();
847
848    /*
849     * init can allocate pages on any node
850     */
851    set_mems_allowed(node_possible_map);
852    /*
853     * init can run on any cpu.
854     */
855    set_cpus_allowed_ptr(current, cpu_all_mask);
856    /*
857     * Tell the world that we're going to be the grim
858     * reaper of innocent orphaned children.
859     *
860     * We don't want people to have to make incorrect
861     * assumptions about where in the task array this
862     * can be found.
863     */
864    init_pid_ns.child_reaper = current;
865
866    cad_pid = task_pid(current);
867
868    smp_prepare_cpus(setup_max_cpus);
869
870    do_pre_smp_initcalls();
871    start_boot_trace();
872
873    smp_init();
874    sched_init_smp();
875
876    do_basic_setup();
877
878    /*
879     * check if there is an early userspace init. If yes, let it do all
880     * the work
881     */
882
883    if (!ramdisk_execute_command)
884        ramdisk_execute_command = "/init";
885
886    if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
887        ramdisk_execute_command = NULL;
888        prepare_namespace();
889    }
890
891    /*
892     * Ok, we have completed the initial bootup, and
893     * we're essentially up and running. Get rid of the
894     * initmem segments and start the user-mode stuff..
895     */
896
897    init_post();
898    return 0;
899}
900

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