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