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/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>
71
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>
77
78#ifdef CONFIG_X86_LOCAL_APIC
79#include <asm/smp.h>
80#endif
81
82static int kernel_init(void *);
83
84extern void init_IRQ(void);
85extern void fork_init(unsigned long);
86extern void mca_init(void);
87extern void sbus_init(void);
88extern void prio_tree_init(void);
89extern void radix_tree_init(void);
90#ifndef CONFIG_DEBUG_RODATA
91static inline void mark_rodata_ro(void) { }
92#endif
93
94#ifdef CONFIG_TC
95extern void tc_init(void);
96#endif
97
98/*
99 * Debug helper: via this flag we know that we are in 'early bootup code'
100 * where only the boot processor is running with IRQ disabled. This means
101 * two things - IRQ must not be enabled before the flag is cleared and some
102 * operations which are not allowed with IRQ disabled are allowed while the
103 * flag is set.
104 */
105bool early_boot_irqs_disabled __read_mostly;
106
107enum system_states system_state __read_mostly;
108EXPORT_SYMBOL(system_state);
109
110/*
111 * Boot command-line arguments
112 */
113#define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
114#define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
115
116extern void time_init(void);
117/* Default late time init is NULL. archs can override this later. */
118void (*__initdata late_time_init)(void);
119extern void softirq_init(void);
120
121/* Untouched command line saved by arch-specific code. */
122char __initdata boot_command_line[COMMAND_LINE_SIZE];
123/* Untouched saved command line (eg. for /proc) */
124char *saved_command_line;
125/* Command line for parameter parsing */
126static char *static_command_line;
127
128static char *execute_command;
129static char *ramdisk_execute_command;
130
131/*
132 * If set, this is an indication to the drivers that reset the underlying
133 * device before going ahead with the initialization otherwise driver might
134 * rely on the BIOS and skip the reset operation.
135 *
136 * This is useful if kernel is booting in an unreliable environment.
137 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
138 * skipped and devices will be in unknown state.
139 */
140unsigned int reset_devices;
141EXPORT_SYMBOL(reset_devices);
142
143static int __init set_reset_devices(char *str)
144{
145    reset_devices = 1;
146    return 1;
147}
148
149__setup("reset_devices", set_reset_devices);
150
151static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
152const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
153static const char *panic_later, *panic_param;
154
155extern const struct obs_kernel_param __setup_start[], __setup_end[];
156
157static int __init obsolete_checksetup(char *line)
158{
159    const struct obs_kernel_param *p;
160    int had_early_param = 0;
161
162    p = __setup_start;
163    do {
164        int n = strlen(p->str);
165        if (parameqn(line, p->str, n)) {
166            if (p->early) {
167                /* Already done in parse_early_param?
168                 * (Needs exact match on param part).
169                 * Keep iterating, as we can have early
170                 * params and __setups of same names 8( */
171                if (line[n] == '\0' || line[n] == '=')
172                    had_early_param = 1;
173            } else if (!p->setup_func) {
174                printk(KERN_WARNING "Parameter %s is obsolete,"
175                       " ignored\n", p->str);
176                return 1;
177            } else if (p->setup_func(line + n))
178                return 1;
179        }
180        p++;
181    } while (p < __setup_end);
182
183    return had_early_param;
184}
185
186/*
187 * This should be approx 2 Bo*oMips to start (note initial shift), and will
188 * still work even if initially too large, it will just take slightly longer
189 */
190unsigned long loops_per_jiffy = (1<<12);
191
192EXPORT_SYMBOL(loops_per_jiffy);
193
194static int __init debug_kernel(char *str)
195{
196    console_loglevel = 10;
197    return 0;
198}
199
200static int __init quiet_kernel(char *str)
201{
202    console_loglevel = 4;
203    return 0;
204}
205
206early_param("debug", debug_kernel);
207early_param("quiet", quiet_kernel);
208
209static int __init loglevel(char *str)
210{
211    int newlevel;
212
213    /*
214     * Only update loglevel value when a correct setting was passed,
215     * to prevent blind crashes (when loglevel being set to 0) that
216     * are quite hard to debug
217     */
218    if (get_option(&str, &newlevel)) {
219        console_loglevel = newlevel;
220        return 0;
221    }
222
223    return -EINVAL;
224}
225
226early_param("loglevel", loglevel);
227
228/* Change NUL term back to "=", to make "param" the whole string. */
229static int __init repair_env_string(char *param, char *val)
230{
231    if (val) {
232        /* param=val or param="val"? */
233        if (val == param+strlen(param)+1)
234            val[-1] = '=';
235        else if (val == param+strlen(param)+2) {
236            val[-2] = '=';
237            memmove(val-1, val, strlen(val)+1);
238            val--;
239        } else
240            BUG();
241    }
242    return 0;
243}
244
245/*
246 * Unknown boot options get handed to init, unless they look like
247 * unused parameters (modprobe will find them in /proc/cmdline).
248 */
249static int __init unknown_bootoption(char *param, char *val)
250{
251    repair_env_string(param, val);
252
253    /* Handle obsolete-style parameters */
254    if (obsolete_checksetup(param))
255        return 0;
256
257    /* Unused module parameter. */
258    if (strchr(param, '.') && (!val || strchr(param, '.') < val))
259        return 0;
260
261    if (panic_later)
262        return 0;
263
264    if (val) {
265        /* Environment option */
266        unsigned int i;
267        for (i = 0; envp_init[i]; i++) {
268            if (i == MAX_INIT_ENVS) {
269                panic_later = "Too many boot env vars at `%s'";
270                panic_param = param;
271            }
272            if (!strncmp(param, envp_init[i], val - param))
273                break;
274        }
275        envp_init[i] = param;
276    } else {
277        /* Command line option */
278        unsigned int i;
279        for (i = 0; argv_init[i]; i++) {
280            if (i == MAX_INIT_ARGS) {
281                panic_later = "Too many boot init vars at `%s'";
282                panic_param = param;
283            }
284        }
285        argv_init[i] = param;
286    }
287    return 0;
288}
289
290static int __init init_setup(char *str)
291{
292    unsigned int i;
293
294    execute_command = str;
295    /*
296     * In case LILO is going to boot us with default command line,
297     * it prepends "auto" before the whole cmdline which makes
298     * the shell think it should execute a script with such name.
299     * So we ignore all arguments entered _before_ init=... [MJ]
300     */
301    for (i = 1; i < MAX_INIT_ARGS; i++)
302        argv_init[i] = NULL;
303    return 1;
304}
305__setup("init=", init_setup);
306
307static int __init rdinit_setup(char *str)
308{
309    unsigned int i;
310
311    ramdisk_execute_command = str;
312    /* See "auto" comment in init_setup */
313    for (i = 1; i < MAX_INIT_ARGS; i++)
314        argv_init[i] = NULL;
315    return 1;
316}
317__setup("rdinit=", rdinit_setup);
318
319#ifndef CONFIG_SMP
320static const unsigned int setup_max_cpus = NR_CPUS;
321#ifdef CONFIG_X86_LOCAL_APIC
322static void __init smp_init(void)
323{
324    APIC_init_uniprocessor();
325}
326#else
327#define smp_init() do { } while (0)
328#endif
329
330static inline void setup_nr_cpu_ids(void) { }
331static inline void smp_prepare_cpus(unsigned int maxcpus) { }
332#endif
333
334/*
335 * We need to store the untouched command line for future reference.
336 * We also need to store the touched command line since the parameter
337 * parsing is performed in place, and we should allow a component to
338 * store reference of name/value for future reference.
339 */
340static void __init setup_command_line(char *command_line)
341{
342    saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
343    static_command_line = alloc_bootmem(strlen (command_line)+1);
344    strcpy (saved_command_line, boot_command_line);
345    strcpy (static_command_line, command_line);
346}
347
348/*
349 * We need to finalize in a non-__init function or else race conditions
350 * between the root thread and the init thread may cause start_kernel to
351 * be reaped by free_initmem before the root thread has proceeded to
352 * cpu_idle.
353 *
354 * gcc-3.4 accidentally inlines this function, so use noinline.
355 */
356
357static __initdata DECLARE_COMPLETION(kthreadd_done);
358
359static noinline void __init_refok rest_init(void)
360{
361    int pid;
362
363    rcu_scheduler_starting();
364    /*
365     * We need to spawn init first so that it obtains pid 1, however
366     * the init task will end up wanting to create kthreads, which, if
367     * we schedule it before we create kthreadd, will OOPS.
368     */
369    kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
370    numa_default_policy();
371    pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
372    rcu_read_lock();
373    kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
374    rcu_read_unlock();
375    complete(&kthreadd_done);
376
377    /*
378     * The boot idle thread must execute schedule()
379     * at least once to get things moving:
380     */
381    init_idle_bootup_task(current);
382    schedule_preempt_disabled();
383    /* Call into cpu_idle with preempt disabled */
384    cpu_idle();
385}
386
387/* Check for early params. */
388static int __init do_early_param(char *param, char *val)
389{
390    const struct obs_kernel_param *p;
391
392    for (p = __setup_start; p < __setup_end; p++) {
393        if ((p->early && parameq(param, p->str)) ||
394            (strcmp(param, "console") == 0 &&
395             strcmp(p->str, "earlycon") == 0)
396        ) {
397            if (p->setup_func(val) != 0)
398                printk(KERN_WARNING
399                       "Malformed early option '%s'\n", param);
400        }
401    }
402    /* We accept everything at this stage. */
403    return 0;
404}
405
406void __init parse_early_options(char *cmdline)
407{
408    parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
409}
410
411/* Arch code calls this early on, or if not, just before other parsing. */
412void __init parse_early_param(void)
413{
414    static __initdata int done = 0;
415    static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
416
417    if (done)
418        return;
419
420    /* All fall through to do_early_param. */
421    strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
422    parse_early_options(tmp_cmdline);
423    done = 1;
424}
425
426/*
427 * Activate the first processor.
428 */
429
430static void __init boot_cpu_init(void)
431{
432    int cpu = smp_processor_id();
433    /* Mark the boot cpu "present", "online" etc for SMP and UP case */
434    set_cpu_online(cpu, true);
435    set_cpu_active(cpu, true);
436    set_cpu_present(cpu, true);
437    set_cpu_possible(cpu, true);
438}
439
440void __init __weak smp_setup_processor_id(void)
441{
442}
443
444void __init __weak thread_info_cache_init(void)
445{
446}
447
448/*
449 * Set up kernel memory allocators
450 */
451static void __init mm_init(void)
452{
453    /*
454     * page_cgroup requires contiguous pages,
455     * bigger than MAX_ORDER unless SPARSEMEM.
456     */
457    page_cgroup_init_flatmem();
458    mem_init();
459    kmem_cache_init();
460    percpu_init_late();
461    pgtable_cache_init();
462    vmalloc_init();
463}
464
465asmlinkage void __init start_kernel(void)
466{
467    char * command_line;
468    extern const struct kernel_param __start___param[], __stop___param[];
469
470    /*
471     * Need to run as early as possible, to initialize the
472     * lockdep hash:
473     */
474    lockdep_init();
475    smp_setup_processor_id();
476    debug_objects_early_init();
477
478    /*
479     * Set up the the initial canary ASAP:
480     */
481    boot_init_stack_canary();
482
483    cgroup_init_early();
484
485    local_irq_disable();
486    early_boot_irqs_disabled = true;
487
488/*
489 * Interrupts are still disabled. Do necessary setups, then
490 * enable them
491 */
492    tick_init();
493    boot_cpu_init();
494    page_address_init();
495    printk(KERN_NOTICE "%s", linux_banner);
496    setup_arch(&command_line);
497    mm_init_owner(&init_mm, &init_task);
498    mm_init_cpumask(&init_mm);
499    setup_command_line(command_line);
500    setup_nr_cpu_ids();
501    setup_per_cpu_areas();
502    smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
503
504    build_all_zonelists(NULL);
505    page_alloc_init();
506
507    printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
508    parse_early_param();
509    parse_args("Booting kernel", static_command_line, __start___param,
510           __stop___param - __start___param,
511           0, 0, &unknown_bootoption);
512
513    jump_label_init();
514
515    /*
516     * These use large bootmem allocations and must precede
517     * kmem_cache_init()
518     */
519    setup_log_buf(0);
520    pidhash_init();
521    vfs_caches_init_early();
522    sort_main_extable();
523    trap_init();
524    mm_init();
525
526    /*
527     * Set up the scheduler prior starting any interrupts (such as the
528     * timer interrupt). Full topology setup happens at smp_init()
529     * time - but meanwhile we still have a functioning scheduler.
530     */
531    sched_init();
532    /*
533     * Disable preemption - early bootup scheduling is extremely
534     * fragile until we cpu_idle() for the first time.
535     */
536    preempt_disable();
537    if (!irqs_disabled()) {
538        printk(KERN_WARNING "start_kernel(): bug: interrupts were "
539                "enabled *very* early, fixing it\n");
540        local_irq_disable();
541    }
542    idr_init_cache();
543    perf_event_init();
544    rcu_init();
545    radix_tree_init();
546    /* init some links before init_ISA_irqs() */
547    early_irq_init();
548    init_IRQ();
549    prio_tree_init();
550    init_timers();
551    hrtimers_init();
552    softirq_init();
553    timekeeping_init();
554    time_init();
555    profile_init();
556    call_function_init();
557    if (!irqs_disabled())
558        printk(KERN_CRIT "start_kernel(): bug: interrupts were "
559                 "enabled early\n");
560    early_boot_irqs_disabled = false;
561    local_irq_enable();
562
563    /* Interrupts are enabled now so all GFP allocations are safe. */
564    gfp_allowed_mask = __GFP_BITS_MASK;
565
566    kmem_cache_init_late();
567
568    /*
569     * HACK ALERT! This is early. We're enabling the console before
570     * we've done PCI setups etc, and console_init() must be aware of
571     * this. But we do want output early, in case something goes wrong.
572     */
573    console_init();
574    if (panic_later)
575        panic(panic_later, panic_param);
576
577    lockdep_info();
578
579    /*
580     * Need to run this when irqs are enabled, because it wants
581     * to self-test [hard/soft]-irqs on/off lock inversion bugs
582     * too:
583     */
584    locking_selftest();
585
586#ifdef CONFIG_BLK_DEV_INITRD
587    if (initrd_start && !initrd_below_start_ok &&
588        page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
589        printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
590            "disabling it.\n",
591            page_to_pfn(virt_to_page((void *)initrd_start)),
592            min_low_pfn);
593        initrd_start = 0;
594    }
595#endif
596    page_cgroup_init();
597    debug_objects_mem_init();
598    kmemleak_init();
599    setup_per_cpu_pageset();
600    numa_policy_init();
601    if (late_time_init)
602        late_time_init();
603    sched_clock_init();
604    calibrate_delay();
605    pidmap_init();
606    anon_vma_init();
607#ifdef CONFIG_X86
608    if (efi_enabled)
609        efi_enter_virtual_mode();
610#endif
611    thread_info_cache_init();
612    cred_init();
613    fork_init(totalram_pages);
614    proc_caches_init();
615    buffer_init();
616    key_init();
617    security_init();
618    dbg_late_init();
619    vfs_caches_init(totalram_pages);
620    signals_init();
621    /* rootfs populating might need page-writeback */
622    page_writeback_init();
623#ifdef CONFIG_PROC_FS
624    proc_root_init();
625#endif
626    cgroup_init();
627    cpuset_init();
628    taskstats_init_early();
629    delayacct_init();
630
631    check_bugs();
632
633    acpi_early_init(); /* before LAPIC and SMP init */
634    sfi_init_late();
635
636    ftrace_init();
637
638    /* Do the rest non-__init'ed, we're now alive */
639    rest_init();
640}
641
642/* Call all constructor functions linked into the kernel. */
643static void __init do_ctors(void)
644{
645#ifdef CONFIG_CONSTRUCTORS
646    ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
647
648    for (; fn < (ctor_fn_t *) __ctors_end; fn++)
649        (*fn)();
650#endif
651}
652
653bool initcall_debug;
654core_param(initcall_debug, initcall_debug, bool, 0644);
655
656static char msgbuf[64];
657
658static int __init_or_module do_one_initcall_debug(initcall_t fn)
659{
660    ktime_t calltime, delta, rettime;
661    unsigned long long duration;
662    int ret;
663
664    printk(KERN_DEBUG "calling %pF @ %i\n", fn, task_pid_nr(current));
665    calltime = ktime_get();
666    ret = fn();
667    rettime = ktime_get();
668    delta = ktime_sub(rettime, calltime);
669    duration = (unsigned long long) ktime_to_ns(delta) >> 10;
670    printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n", fn,
671        ret, duration);
672
673    return ret;
674}
675
676int __init_or_module do_one_initcall(initcall_t fn)
677{
678    int count = preempt_count();
679    int ret;
680
681    if (initcall_debug)
682        ret = do_one_initcall_debug(fn);
683    else
684        ret = fn();
685
686    msgbuf[0] = 0;
687
688    if (ret && ret != -ENODEV && initcall_debug)
689        sprintf(msgbuf, "error code %d ", ret);
690
691    if (preempt_count() != count) {
692        strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
693        preempt_count() = count;
694    }
695    if (irqs_disabled()) {
696        strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
697        local_irq_enable();
698    }
699    if (msgbuf[0]) {
700        printk("initcall %pF returned with %s\n", fn, msgbuf);
701    }
702
703    return ret;
704}
705
706
707extern initcall_t __initcall_start[];
708extern initcall_t __initcall0_start[];
709extern initcall_t __initcall1_start[];
710extern initcall_t __initcall2_start[];
711extern initcall_t __initcall3_start[];
712extern initcall_t __initcall4_start[];
713extern initcall_t __initcall5_start[];
714extern initcall_t __initcall6_start[];
715extern initcall_t __initcall7_start[];
716extern initcall_t __initcall_end[];
717
718static initcall_t *initcall_levels[] __initdata = {
719    __initcall0_start,
720    __initcall1_start,
721    __initcall2_start,
722    __initcall3_start,
723    __initcall4_start,
724    __initcall5_start,
725    __initcall6_start,
726    __initcall7_start,
727    __initcall_end,
728};
729
730static char *initcall_level_names[] __initdata = {
731    "early parameters",
732    "core parameters",
733    "postcore parameters",
734    "arch parameters",
735    "subsys parameters",
736    "fs parameters",
737    "device parameters",
738    "late parameters",
739};
740
741static void __init do_initcall_level(int level)
742{
743    extern const struct kernel_param __start___param[], __stop___param[];
744    initcall_t *fn;
745
746    strcpy(static_command_line, saved_command_line);
747    parse_args(initcall_level_names[level],
748           static_command_line, __start___param,
749           __stop___param - __start___param,
750           level, level,
751           repair_env_string);
752
753    for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
754        do_one_initcall(*fn);
755}
756
757static void __init do_initcalls(void)
758{
759    int level;
760
761    for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
762        do_initcall_level(level);
763}
764
765/*
766 * Ok, the machine is now initialized. None of the devices
767 * have been touched yet, but the CPU subsystem is up and
768 * running, and memory and process management works.
769 *
770 * Now we can finally start doing some real work..
771 */
772static void __init do_basic_setup(void)
773{
774    cpuset_init_smp();
775    usermodehelper_init();
776    shmem_init();
777    driver_init();
778    init_irq_proc();
779    do_ctors();
780    usermodehelper_enable();
781    do_initcalls();
782}
783
784static void __init do_pre_smp_initcalls(void)
785{
786    initcall_t *fn;
787
788    for (fn = __initcall_start; fn < __initcall0_start; fn++)
789        do_one_initcall(*fn);
790}
791
792static void run_init_process(const char *init_filename)
793{
794    argv_init[0] = init_filename;
795    kernel_execve(init_filename, argv_init, envp_init);
796}
797
798/* This is a non __init function. Force it to be noinline otherwise gcc
799 * makes it inline to init() and it becomes part of init.text section
800 */
801static noinline int init_post(void)
802{
803    /* need to finish all async __init code before freeing the memory */
804    async_synchronize_full();
805    free_initmem();
806    mark_rodata_ro();
807    system_state = SYSTEM_RUNNING;
808    numa_default_policy();
809
810
811    current->signal->flags |= SIGNAL_UNKILLABLE;
812
813    if (ramdisk_execute_command) {
814        run_init_process(ramdisk_execute_command);
815        printk(KERN_WARNING "Failed to execute %s\n",
816                ramdisk_execute_command);
817    }
818
819    /*
820     * We try each of these until one succeeds.
821     *
822     * The Bourne shell can be used instead of init if we are
823     * trying to recover a really broken machine.
824     */
825    if (execute_command) {
826        run_init_process(execute_command);
827        printk(KERN_WARNING "Failed to execute %s. Attempting "
828                    "defaults...\n", execute_command);
829    }
830    run_init_process("/sbin/init");
831    run_init_process("/etc/init");
832    run_init_process("/bin/init");
833    run_init_process("/bin/sh");
834
835    panic("No init found. Try passing init= option to kernel. "
836          "See Linux Documentation/init.txt for guidance.");
837}
838
839static int __init kernel_init(void * unused)
840{
841    /*
842     * Wait until kthreadd is all set-up.
843     */
844    wait_for_completion(&kthreadd_done);
845    /*
846     * init can allocate pages on any node
847     */
848    set_mems_allowed(node_states[N_HIGH_MEMORY]);
849    /*
850     * init can run on any cpu.
851     */
852    set_cpus_allowed_ptr(current, cpu_all_mask);
853
854    cad_pid = task_pid(current);
855
856    smp_prepare_cpus(setup_max_cpus);
857
858    do_pre_smp_initcalls();
859    lockup_detector_init();
860
861    smp_init();
862    sched_init_smp();
863
864    do_basic_setup();
865
866    /* Open the /dev/console on the rootfs, this should never fail */
867    if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
868        printk(KERN_WARNING "Warning: unable to open an initial console.\n");
869
870    (void) sys_dup(0);
871    (void) sys_dup(0);
872    /*
873     * check if there is an early userspace init. If yes, let it do all
874     * the work
875     */
876
877    if (!ramdisk_execute_command)
878        ramdisk_execute_command = "/init";
879
880    if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
881        ramdisk_execute_command = NULL;
882        prepare_namespace();
883    }
884
885    /*
886     * Ok, we have completed the initial bootup, and
887     * we're essentially up and running. Get rid of the
888     * initmem segments and start the user-mode stuff..
889     */
890
891    init_post();
892    return 0;
893}
894

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