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/cgroup.h> 43 #include <linux/efi.h> 44 #include <linux/tick.h> 45 #include <linux/interrupt.h> 46 #include <linux/taskstats_kern.h> 47 #include <linux/delayacct.h> 48 #include <linux/unistd.h> 49 #include <linux/rmap.h> 50 #include <linux/mempolicy.h> 51 #include <linux/key.h> 52 #include <linux/unwind.h> 53 #include <linux/buffer_head.h> 54 #include <linux/debug_locks.h> 55 #include <linux/lockdep.h> 56 #include <linux/pid_namespace.h> 57 #include <linux/device.h> 58 #include <linux/kthread.h> 59 60 #include <asm/io.h> 61 #include <asm/bugs.h> 62 #include <asm/setup.h> 63 #include <asm/sections.h> 64 #include <asm/cacheflush.h> 65 66 #ifdef CONFIG_X86_LOCAL_APIC 67 #include <asm/smp.h> 68 #endif 69 70 /* 71 * This is one of the first .c files built. Error out early if we have compiler 72 * trouble. 73 */ 74 75 #if __GNUC__ == 4 && __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ == 0 76 #warning gcc-4.1.0 is known to miscompile the kernel. A different compiler version is recommended. 77 #endif 78 79 static int kernel_init(void *); 80 81 extern void init_IRQ(void); 82 extern void fork_init(unsigned long); 83 extern void mca_init(void); 84 extern void sbus_init(void); 85 extern void signals_init(void); 86 extern void pidhash_init(void); 87 extern void pidmap_init(void); 88 extern void prio_tree_init(void); 89 extern void radix_tree_init(void); 90 extern void free_initmem(void); 91 #ifdef CONFIG_ACPI 92 extern void acpi_early_init(void); 93 #else 94 static inline void acpi_early_init(void) { } 95 #endif 96 #ifndef CONFIG_DEBUG_RODATA 97 static inline void mark_rodata_ro(void) { } 98 #endif 99 100 #ifdef CONFIG_TC 101 extern void tc_init(void); 102 #endif 103 104 enum system_states system_state; 105 EXPORT_SYMBOL(system_state); 106 107 /* 108 * Boot command-line arguments 109 */ 110 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT 111 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT 112 113 extern void time_init(void); 114 /* Default late time init is NULL. archs can override this later. */ 115 void (*late_time_init)(void); 116 extern void softirq_init(void); 117 118 /* Untouched command line saved by arch-specific code. */ 119 char __initdata boot_command_line[COMMAND_LINE_SIZE]; 120 /* Untouched saved command line (eg. for /proc) */ 121 char *saved_command_line; 122 /* Command line for parameter parsing */ 123 static char *static_command_line; 124 125 static char *execute_command; 126 static char *ramdisk_execute_command; 127 128 #ifdef CONFIG_SMP 129 /* Setup configured maximum number of CPUs to activate */ 130 static unsigned int __initdata max_cpus = NR_CPUS; 131 132 /* 133 * Setup routine for controlling SMP activation 134 * 135 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP 136 * activation entirely (the MPS table probe still happens, though). 137 * 138 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer 139 * greater than 0, limits the maximum number of CPUs activated in 140 * SMP mode to <NUM>. 141 */ 142 #ifndef CONFIG_X86_IO_APIC 143 static inline void disable_ioapic_setup(void) {}; 144 #endif 145 146 static int __init nosmp(char *str) 147 { 148 max_cpus = 0; 149 disable_ioapic_setup(); 150 return 0; 151 } 152 153 early_param("nosmp", nosmp); 154 155 static int __init maxcpus(char *str) 156 { 157 get_option(&str, &max_cpus); 158 if (max_cpus == 0) 159 disable_ioapic_setup(); 160 161 return 0; 162 } 163 164 early_param("maxcpus", maxcpus); 165 #else 166 #define max_cpus NR_CPUS 167 #endif 168 169 /* 170 * If set, this is an indication to the drivers that reset the underlying 171 * device before going ahead with the initialization otherwise driver might 172 * rely on the BIOS and skip the reset operation. 173 * 174 * This is useful if kernel is booting in an unreliable environment. 175 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been 176 * skipped and devices will be in unknown state. 177 */ 178 unsigned int reset_devices; 179 EXPORT_SYMBOL(reset_devices); 180 181 static int __init set_reset_devices(char *str) 182 { 183 reset_devices = 1; 184 return 1; 185 } 186 187 __setup("reset_devices", set_reset_devices); 188 189 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, }; 190 char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, }; 191 static const char *panic_later, *panic_param; 192 193 extern struct obs_kernel_param __setup_start[], __setup_end[]; 194 195 static int __init obsolete_checksetup(char *line) 196 { 197 struct obs_kernel_param *p; 198 int had_early_param = 0; 199 200 p = __setup_start; 201 do { 202 int n = strlen(p->str); 203 if (!strncmp(line, p->str, n)) { 204 if (p->early) { 205 /* Already done in parse_early_param? 206 * (Needs exact match on param part). 207 * Keep iterating, as we can have early 208 * params and __setups of same names 8( */ 209 if (line[n] == '\0' || line[n] == '=') 210 had_early_param = 1; 211 } else if (!p->setup_func) { 212 printk(KERN_WARNING "Parameter %s is obsolete," 213 " ignored\n", p->str); 214 return 1; 215 } else if (p->setup_func(line + n)) 216 return 1; 217 } 218 p++; 219 } while (p < __setup_end); 220 221 return had_early_param; 222 } 223 224 /* 225 * This should be approx 2 Bo*oMips to start (note initial shift), and will 226 * still work even if initially too large, it will just take slightly longer 227 */ 228 unsigned long loops_per_jiffy = (1<<12); 229 230 EXPORT_SYMBOL(loops_per_jiffy); 231 232 static int __init debug_kernel(char *str) 233 { 234 if (*str) 235 return 0; 236 console_loglevel = 10; 237 return 1; 238 } 239 240 static int __init quiet_kernel(char *str) 241 { 242 if (*str) 243 return 0; 244 console_loglevel = 4; 245 return 1; 246 } 247 248 __setup("debug", debug_kernel); 249 __setup("quiet", quiet_kernel); 250 251 static int __init loglevel(char *str) 252 { 253 get_option(&str, &console_loglevel); 254 return 1; 255 } 256 257 __setup("loglevel=", loglevel); 258 259 /* 260 * Unknown boot options get handed to init, unless they look like 261 * failed parameters 262 */ 263 static int __init unknown_bootoption(char *param, char *val) 264 { 265 /* Change NUL term back to "=", to make "param" the whole string. */ 266 if (val) { 267 /* param=val or param="val"? */ 268 if (val == param+strlen(param)+1) 269 val[-1] = '='; 270 else if (val == param+strlen(param)+2) { 271 val[-2] = '='; 272 memmove(val-1, val, strlen(val)+1); 273 val--; 274 } else 275 BUG(); 276 } 277 278 /* Handle obsolete-style parameters */ 279 if (obsolete_checksetup(param)) 280 return 0; 281 282 /* 283 * Preemptive maintenance for "why didn't my misspelled command 284 * line work?" 285 */ 286 if (strchr(param, '.') && (!val || strchr(param, '.') < val)) { 287 printk(KERN_ERR "Unknown boot option `%s': ignoring\n", param); 288 return 0; 289 } 290 291 if (panic_later) 292 return 0; 293 294 if (val) { 295 /* Environment option */ 296 unsigned int i; 297 for (i = 0; envp_init[i]; i++) { 298 if (i == MAX_INIT_ENVS) { 299 panic_later = "Too many boot env vars at `%s'"; 300 panic_param = param; 301 } 302 if (!strncmp(param, envp_init[i], val - param)) 303 break; 304 } 305 envp_init[i] = param; 306 } else { 307 /* Command line option */ 308 unsigned int i; 309 for (i = 0; argv_init[i]; i++) { 310 if (i == MAX_INIT_ARGS) { 311 panic_later = "Too many boot init vars at `%s'"; 312 panic_param = param; 313 } 314 } 315 argv_init[i] = param; 316 } 317 return 0; 318 } 319 320 static int __init init_setup(char *str) 321 { 322 unsigned int i; 323 324 execute_command = str; 325 /* 326 * In case LILO is going to boot us with default command line, 327 * it prepends "auto" before the whole cmdline which makes 328 * the shell think it should execute a script with such name. 329 * So we ignore all arguments entered _before_ init=... [MJ] 330 */ 331 for (i = 1; i < MAX_INIT_ARGS; i++) 332 argv_init[i] = NULL; 333 return 1; 334 } 335 __setup("init=", init_setup); 336 337 static int __init rdinit_setup(char *str) 338 { 339 unsigned int i; 340 341 ramdisk_execute_command = str; 342 /* See "auto" comment in init_setup */ 343 for (i = 1; i < MAX_INIT_ARGS; i++) 344 argv_init[i] = NULL; 345 return 1; 346 } 347 __setup("rdinit=", rdinit_setup); 348 349 #ifndef CONFIG_SMP 350 351 #ifdef CONFIG_X86_LOCAL_APIC 352 static void __init smp_init(void) 353 { 354 APIC_init_uniprocessor(); 355 } 356 #else 357 #define smp_init() do { } while (0) 358 #endif 359 360 static inline void setup_per_cpu_areas(void) { } 361 static inline void smp_prepare_cpus(unsigned int maxcpus) { } 362 363 #else 364 365 #ifdef __GENERIC_PER_CPU 366 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly; 367 368 EXPORT_SYMBOL(__per_cpu_offset); 369 370 static void __init setup_per_cpu_areas(void) 371 { 372 unsigned long size, i; 373 char *ptr; 374 unsigned long nr_possible_cpus = num_possible_cpus(); 375 376 /* Copy section for each CPU (we discard the original) */ 377 size = ALIGN(PERCPU_ENOUGH_ROOM, PAGE_SIZE); 378 ptr = alloc_bootmem_pages(size * nr_possible_cpus); 379 380 for_each_possible_cpu(i) { 381 __per_cpu_offset[i] = ptr - __per_cpu_start; 382 memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start); 383 ptr += size; 384 } 385 } 386 #endif /* !__GENERIC_PER_CPU */ 387 388 /* Called by boot processor to activate the rest. */ 389 static void __init smp_init(void) 390 { 391 unsigned int cpu; 392 393 /* FIXME: This should be done in userspace --RR */ 394 for_each_present_cpu(cpu) { 395 if (num_online_cpus() >= max_cpus) 396 break; 397 if (!cpu_online(cpu)) 398 cpu_up(cpu); 399 } 400 401 /* Any cleanup work */ 402 printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus()); 403 smp_cpus_done(max_cpus); 404 } 405 406 #endif 407 408 /* 409 * We need to store the untouched command line for future reference. 410 * We also need to store the touched command line since the parameter 411 * parsing is performed in place, and we should allow a component to 412 * store reference of name/value for future reference. 413 */ 414 static void __init setup_command_line(char *command_line) 415 { 416 saved_command_line = alloc_bootmem(strlen (boot_command_line)+1); 417 static_command_line = alloc_bootmem(strlen (command_line)+1); 418 strcpy (saved_command_line, boot_command_line); 419 strcpy (static_command_line, command_line); 420 } 421 422 /* 423 * We need to finalize in a non-__init function or else race conditions 424 * between the root thread and the init thread may cause start_kernel to 425 * be reaped by free_initmem before the root thread has proceeded to 426 * cpu_idle. 427 * 428 * gcc-3.4 accidentally inlines this function, so use noinline. 429 */ 430 431 static void noinline __init_refok rest_init(void) 432 __releases(kernel_lock) 433 { 434 int pid; 435 436 kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND); 437 numa_default_policy(); 438 pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES); 439 kthreadd_task = find_task_by_pid(pid); 440 unlock_kernel(); 441 442 /* 443 * The boot idle thread must execute schedule() 444 * at least once to get things moving: 445 */ 446 init_idle_bootup_task(current); 447 preempt_enable_no_resched(); 448 schedule(); 449 preempt_disable(); 450 451 /* Call into cpu_idle with preempt disabled */ 452 cpu_idle(); 453 } 454 455 /* Check for early params. */ 456 static int __init do_early_param(char *param, char *val) 457 { 458 struct obs_kernel_param *p; 459 460 for (p = __setup_start; p < __setup_end; p++) { 461 if ((p->early && strcmp(param, p->str) == 0) || 462 (strcmp(param, "console") == 0 && 463 strcmp(p->str, "earlycon") == 0) 464 ) { 465 if (p->setup_func(val) != 0) 466 printk(KERN_WARNING 467 "Malformed early option '%s'\n", param); 468 } 469 } 470 /* We accept everything at this stage. */ 471 return 0; 472 } 473 474 /* Arch code calls this early on, or if not, just before other parsing. */ 475 void __init parse_early_param(void) 476 { 477 static __initdata int done = 0; 478 static __initdata char tmp_cmdline[COMMAND_LINE_SIZE]; 479 480 if (done) 481 return; 482 483 /* All fall through to do_early_param. */ 484 strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE); 485 parse_args("early options", tmp_cmdline, NULL, 0, do_early_param); 486 done = 1; 487 } 488 489 /* 490 * Activate the first processor. 491 */ 492 493 static void __init boot_cpu_init(void) 494 { 495 int cpu = smp_processor_id(); 496 /* Mark the boot cpu "present", "online" etc for SMP and UP case */ 497 cpu_set(cpu, cpu_online_map); 498 cpu_set(cpu, cpu_present_map); 499 cpu_set(cpu, cpu_possible_map); 500 } 501 502 void __init __attribute__((weak)) smp_setup_processor_id(void) 503 { 504 } 505 506 asmlinkage void __init start_kernel(void) 507 { 508 char * command_line; 509 extern struct kernel_param __start___param[], __stop___param[]; 510 511 smp_setup_processor_id(); 512 513 /* 514 * Need to run as early as possible, to initialize the 515 * lockdep hash: 516 */ 517 unwind_init(); 518 lockdep_init(); 519 cgroup_init_early(); 520 521 local_irq_disable(); 522 early_boot_irqs_off(); 523 early_init_irq_lock_class(); 524 525 /* 526 * Interrupts are still disabled. Do necessary setups, then 527 * enable them 528 */ 529 lock_kernel(); 530 tick_init(); 531 boot_cpu_init(); 532 page_address_init(); 533 printk(KERN_NOTICE); 534 printk(linux_banner); 535 setup_arch(&command_line); 536 setup_command_line(command_line); 537 unwind_setup(); 538 setup_per_cpu_areas(); 539 smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */ 540 541 /* 542 * Set up the scheduler prior starting any interrupts (such as the 543 * timer interrupt). Full topology setup happens at smp_init() 544 * time - but meanwhile we still have a functioning scheduler. 545 */ 546 sched_init(); 547 /* 548 * Disable preemption - early bootup scheduling is extremely 549 * fragile until we cpu_idle() for the first time. 550 */ 551 preempt_disable(); 552 build_all_zonelists(); 553 page_alloc_init(); 554 printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line); 555 parse_early_param(); 556 parse_args("Booting kernel", static_command_line, __start___param, 557 __stop___param - __start___param, 558 &unknown_bootoption); 559 if (!irqs_disabled()) { 560 printk(KERN_WARNING "start_kernel(): bug: interrupts were " 561 "enabled *very* early, fixing it\n"); 562 local_irq_disable(); 563 } 564 sort_main_extable(); 565 trap_init(); 566 rcu_init(); 567 init_IRQ(); 568 pidhash_init(); 569 init_timers(); 570 hrtimers_init(); 571 softirq_init(); 572 timekeeping_init(); 573 time_init(); 574 profile_init(); 575 if (!irqs_disabled()) 576 printk("start_kernel(): bug: interrupts were enabled early\n"); 577 early_boot_irqs_on(); 578 local_irq_enable(); 579 580 /* 581 * HACK ALERT! This is early. We're enabling the console before 582 * we've done PCI setups etc, and console_init() must be aware of 583 * this. But we do want output early, in case something goes wrong. 584 */ 585 console_init(); 586 if (panic_later) 587 panic(panic_later, panic_param); 588 589 lockdep_info(); 590 591 /* 592 * Need to run this when irqs are enabled, because it wants 593 * to self-test [hard/soft]-irqs on/off lock inversion bugs 594 * too: 595 */ 596 locking_selftest(); 597 598 #ifdef CONFIG_BLK_DEV_INITRD 599 if (initrd_start && !initrd_below_start_ok && 600 initrd_start < min_low_pfn << PAGE_SHIFT) { 601 printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - " 602 "disabling it.\n",initrd_start,min_low_pfn << PAGE_SHIFT); 603 initrd_start = 0; 604 } 605 #endif 606 vfs_caches_init_early(); 607 cpuset_init_early(); 608 mem_init(); 609 kmem_cache_init(); 610 setup_per_cpu_pageset(); 611 numa_policy_init(); 612 if (late_time_init) 613 late_time_init(); 614 calibrate_delay(); 615 pidmap_init(); 616 pgtable_cache_init(); 617 prio_tree_init(); 618 anon_vma_init(); 619 #ifdef CONFIG_X86 620 if (efi_enabled) 621 efi_enter_virtual_mode(); 622 #endif 623 fork_init(num_physpages); 624 proc_caches_init(); 625 buffer_init(); 626 unnamed_dev_init(); 627 key_init(); 628 security_init(); 629 vfs_caches_init(num_physpages); 630 radix_tree_init(); 631 signals_init(); 632 /* rootfs populating might need page-writeback */ 633 page_writeback_init(); 634 #ifdef CONFIG_PROC_FS 635 proc_root_init(); 636 #endif 637 cgroup_init(); 638 cpuset_init(); 639 taskstats_init_early(); 640 delayacct_init(); 641 642 check_bugs(); 643 644 acpi_early_init(); /* before LAPIC and SMP init */ 645 646 /* Do the rest non-__init'ed, we're now alive */ 647 rest_init(); 648 } 649 650 static int __initdata initcall_debug; 651 652 static int __init initcall_debug_setup(char *str) 653 { 654 initcall_debug = 1; 655 return 1; 656 } 657 __setup("initcall_debug", initcall_debug_setup); 658 659 extern initcall_t __initcall_start[], __initcall_end[]; 660 661 static void __init do_initcalls(void) 662 { 663 initcall_t *call; 664 int count = preempt_count(); 665 666 for (call = __initcall_start; call < __initcall_end; call++) { 667 ktime_t t0, t1, delta; 668 char *msg = NULL; 669 char msgbuf[40]; 670 int result; 671 672 if (initcall_debug) { 673 printk("Calling initcall 0x%p", *call); 674 print_fn_descriptor_symbol(": %s()", 675 (unsigned long) *call); 676 printk("\n"); 677 t0 = ktime_get(); 678 } 679 680 result = (*call)(); 681 682 if (initcall_debug) { 683 t1 = ktime_get(); 684 delta = ktime_sub(t1, t0); 685 686 printk("initcall 0x%p", *call); 687 print_fn_descriptor_symbol(": %s()", 688 (unsigned long) *call); 689 printk(" returned %d.\n", result); 690 691 printk("initcall 0x%p ran for %Ld msecs: ", 692 *call, (unsigned long long)delta.tv64 >> 20); 693 print_fn_descriptor_symbol("%s()\n", 694 (unsigned long) *call); 695 } 696 697 if (result && result != -ENODEV && initcall_debug) { 698 sprintf(msgbuf, "error code %d", result); 699 msg = msgbuf; 700 } 701 if (preempt_count() != count) { 702 msg = "preemption imbalance"; 703 preempt_count() = count; 704 } 705 if (irqs_disabled()) { 706 msg = "disabled interrupts"; 707 local_irq_enable(); 708 } 709 if (msg) { 710 printk(KERN_WARNING "initcall at 0x%p", *call); 711 print_fn_descriptor_symbol(": %s()", 712 (unsigned long) *call); 713 printk(": returned with %s\n", msg); 714 } 715 } 716 717 /* Make sure there is no pending stuff from the initcall sequence */ 718 flush_scheduled_work(); 719 } 720 721 /* 722 * Ok, the machine is now initialized. None of the devices 723 * have been touched yet, but the CPU subsystem is up and 724 * running, and memory and process management works. 725 * 726 * Now we can finally start doing some real work.. 727 */ 728 static void __init do_basic_setup(void) 729 { 730 /* drivers will send hotplug events */ 731 init_workqueues(); 732 usermodehelper_init(); 733 driver_init(); 734 init_irq_proc(); 735 do_initcalls(); 736 } 737 738 static int __initdata nosoftlockup; 739 740 static int __init nosoftlockup_setup(char *str) 741 { 742 nosoftlockup = 1; 743 return 1; 744 } 745 __setup("nosoftlockup", nosoftlockup_setup); 746 747 static void __init do_pre_smp_initcalls(void) 748 { 749 extern int spawn_ksoftirqd(void); 750 #ifdef CONFIG_SMP 751 extern int migration_init(void); 752 753 migration_init(); 754 #endif 755 spawn_ksoftirqd(); 756 if (!nosoftlockup) 757 spawn_softlockup_task(); 758 } 759 760 static void run_init_process(char *init_filename) 761 { 762 argv_init[0] = init_filename; 763 kernel_execve(init_filename, argv_init, envp_init); 764 } 765 766 /* This is a non __init function. Force it to be noinline otherwise gcc 767 * makes it inline to init() and it becomes part of init.text section 768 */ 769 static int noinline init_post(void) 770 { 771 free_initmem(); 772 unlock_kernel(); 773 mark_rodata_ro(); 774 system_state = SYSTEM_RUNNING; 775 numa_default_policy(); 776 777 if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0) 778 printk(KERN_WARNING "Warning: unable to open an initial console.\n"); 779 780 (void) sys_dup(0); 781 (void) sys_dup(0); 782 783 if (ramdisk_execute_command) { 784 run_init_process(ramdisk_execute_command); 785 printk(KERN_WARNING "Failed to execute %s\n", 786 ramdisk_execute_command); 787 } 788 789 /* 790 * We try each of these until one succeeds. 791 * 792 * The Bourne shell can be used instead of init if we are 793 * trying to recover a really broken machine. 794 */ 795 if (execute_command) { 796 run_init_process(execute_command); 797 printk(KERN_WARNING "Failed to execute %s. Attempting " 798 "defaults...\n", execute_command); 799 } 800 run_init_process("/sbin/init"); 801 run_init_process("/etc/init"); 802 run_init_process("/bin/init"); 803 run_init_process("/bin/sh"); 804 805 panic("No init found. Try passing init= option to kernel."); 806 } 807 808 static int __init kernel_init(void * unused) 809 { 810 lock_kernel(); 811 /* 812 * init can run on any cpu. 813 */ 814 set_cpus_allowed(current, CPU_MASK_ALL); 815 /* 816 * Tell the world that we're going to be the grim 817 * reaper of innocent orphaned children. 818 * 819 * We don't want people to have to make incorrect 820 * assumptions about where in the task array this 821 * can be found. 822 */ 823 init_pid_ns.child_reaper = current; 824 825 __set_special_pids(1, 1); 826 cad_pid = task_pid(current); 827 828 smp_prepare_cpus(max_cpus); 829 830 do_pre_smp_initcalls(); 831 832 smp_init(); 833 sched_init_smp(); 834 835 cpuset_init_smp(); 836 837 do_basic_setup(); 838 839 /* 840 * check if there is an early userspace init. If yes, let it do all 841 * the work 842 */ 843 844 if (!ramdisk_execute_command) 845 ramdisk_execute_command = "/init"; 846 847 if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) { 848 ramdisk_execute_command = NULL; 849 prepare_namespace(); 850 } 851 852 /* 853 * Ok, we have completed the initial bootup, and 854 * we're essentially up and running. Get rid of the 855 * initmem segments and start the user-mode stuff.. 856 */ 857 init_post(); 858 return 0; 859 } 860