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 #define __KERNEL_SYSCALLS__
  13
  14 #include <linux/config.h>
  15 #include <linux/types.h>
  16 #include <linux/module.h>
  17 #include <linux/proc_fs.h>
  18 #include <linux/devfs_fs_kernel.h>
  19 #include <linux/kernel.h>
  20 #include <linux/syscalls.h>
  21 #include <linux/string.h>
  22 #include <linux/ctype.h>
  23 #include <linux/delay.h>
  24 #include <linux/utsname.h>
  25 #include <linux/ioport.h>
  26 #include <linux/init.h>
  27 #include <linux/smp_lock.h>
  28 #include <linux/initrd.h>
  29 #include <linux/hdreg.h>
  30 #include <linux/bootmem.h>
  31 #include <linux/tty.h>
  32 #include <linux/gfp.h>
  33 #include <linux/percpu.h>
  34 #include <linux/kmod.h>
  35 #include <linux/kernel_stat.h>
  36 #include <linux/security.h>
  37 #include <linux/workqueue.h>
  38 #include <linux/profile.h>
  39 #include <linux/rcupdate.h>
  40 #include <linux/moduleparam.h>
  41 #include <linux/kallsyms.h>
  42 #include <linux/writeback.h>
  43 #include <linux/cpu.h>
  44 #include <linux/efi.h>
  45 #include <linux/unistd.h>
  46 #include <linux/rmap.h>
  47 #include <linux/mempolicy.h>
  48 #include <linux/key.h>
  49
  50 #include <asm/io.h>
  51 #include <asm/bugs.h>
  52 #include <asm/setup.h>
  53
  54 /*
  55  * This is one of the first .c files built. Error out early
  56  * if we have compiler trouble..
  57  */
  58 #if __GNUC__ == 2 && __GNUC_MINOR__ == 96
  59 #ifdef CONFIG_FRAME_POINTER
  60 #error This compiler cannot compile correctly with frame pointers enabled
  61 #endif
  62 #endif
  63
  64 #ifdef CONFIG_X86_LOCAL_APIC
  65 #include <asm/smp.h>
  66 #endif
  67
  68 /*
  69  * Versions of gcc older than that listed below may actually compile
  70  * and link okay, but the end product can have subtle run time bugs.
  71  * To avoid associated bogus bug reports, we flatly refuse to compile
  72  * with a gcc that is known to be too old from the very beginning.
  73  */
  74 #if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 95)
  75 #error Sorry, your GCC is too old. It builds incorrect kernels.
  76 #endif
  77
  78 extern char *linux_banner;
  79
  80 static int init(void *);
  81
  82 extern void init_IRQ(void);
  83 extern void sock_init(void);
  84 extern void fork_init(unsigned long);
  85 extern void mca_init(void);
  86 extern void sbus_init(void);
  87 extern void sysctl_init(void);
  88 extern void signals_init(void);
  89 extern void buffer_init(void);
  90 extern void pidhash_init(void);
  91 extern void pidmap_init(void);
  92 extern void prio_tree_init(void);
  93 extern void radix_tree_init(void);
  94 extern void free_initmem(void);
  95 extern void populate_rootfs(void);
  96 extern void driver_init(void);
  97 extern void prepare_namespace(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
 104 #ifdef CONFIG_TC
 105 extern void tc_init(void);
 106 #endif
 107
 108 enum system_states system_state;
 109 EXPORT_SYMBOL(system_state);
 110
 111 /*
 112  * Boot command-line arguments
 113  */
 114 #define MAX_INIT_ARGS 32
 115 #define MAX_INIT_ENVS 32
 116
 117 extern void time_init(void);
 118 /* Default late time init is NULL. archs can override this later. */
 119 void (*late_time_init)(void);
 120 extern void softirq_init(void);
 121
 122 /* Untouched command line (eg. for /proc) saved by arch-specific code. */
 123 char saved_command_line[COMMAND_LINE_SIZE];
 124
 125 static char *execute_command;
 126
 127 /* Setup configured maximum number of CPUs to activate */
 128 static unsigned int max_cpus = NR_CPUS;
 129
 130 /*
 131  * Setup routine for controlling SMP activation
 132  *
 133  * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
 134  * activation entirely (the MPS table probe still happens, though).
 135  *
 136  * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
 137  * greater than 0, limits the maximum number of CPUs activated in
 138  * SMP mode to <NUM>.
 139  */
 140 static int __init nosmp(char *str)
 141 {
 142         max_cpus = 0;
 143         return 1;
 144 }
 145
 146 __setup("nosmp", nosmp);
 147
 148 static int __init maxcpus(char *str)
 149 {
 150         get_option(&str, &max_cpus);
 151         return 1;
 152 }
 153
 154 __setup("maxcpus=", maxcpus);
 155
 156 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 157 char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 158 static const char *panic_later, *panic_param;
 159
 160 static int __init obsolete_checksetup(char *line)
 161 {
 162         struct obs_kernel_param *p;
 163         extern struct obs_kernel_param __setup_start, __setup_end;
 164
 165         p = &__setup_start;
 166         do {
 167                 int n = strlen(p->str);
 168                 if (!strncmp(line, p->str, n)) {
 169                         if (p->early) {
 170                                 /* Already done in parse_early_param?  (Needs
 171                                  * exact match on param part) */
 172                                 if (line[n] == '\0' || line[n] == '=')
 173                                         return 1;
 174                         } else if (!p->setup_func) {
 175                                 printk(KERN_WARNING "Parameter %s is obsolete,"
 176                                        " ignored\n", p->str);
 177                                 return 1;
 178                         } else if (p->setup_func(line + n))
 179                                 return 1;
 180                 }
 181                 p++;
 182         } while (p < &__setup_end);
 183         return 0;
 184 }
 185
 186 static unsigned long preset_lpj;
 187 static int __init lpj_setup(char *str)
 188 {
 189         preset_lpj = simple_strtoul(str,NULL,0);
 190         return 1;
 191 }
 192
 193 __setup("lpj=", lpj_setup);
 194
 195 /*
 196  * This should be approx 2 Bo*oMips to start (note initial shift), and will
 197  * still work even if initially too large, it will just take slightly longer
 198  */
 199 unsigned long loops_per_jiffy = (1<<12);
 200
 201 EXPORT_SYMBOL(loops_per_jiffy);
 202
 203 /*
 204  * This is the number of bits of precision for the loops_per_jiffy.  Each
 205  * bit takes on average 1.5/HZ seconds.  This (like the original) is a little
 206  * better than 1%
 207  */
 208 #define LPS_PREC 8
 209
 210 void __devinit calibrate_delay(void)
 211 {
 212         unsigned long ticks, loopbit;
 213         int lps_precision = LPS_PREC;
 214
 215         if (preset_lpj) {
 216                 loops_per_jiffy = preset_lpj;
 217                 printk("Calibrating delay loop (skipped)... "
 218                         "%lu.%02lu BogoMIPS preset\n",
 219                         loops_per_jiffy/(500000/HZ),
 220                         (loops_per_jiffy/(5000/HZ)) % 100);
 221         } else {
 222                 loops_per_jiffy = (1<<12);
 223
 224                 printk(KERN_DEBUG "Calibrating delay loop... ");
 225                 while ((loops_per_jiffy <<= 1) != 0) {
 226                         /* wait for "start of" clock tick */
 227                         ticks = jiffies;
 228                         while (ticks == jiffies)
 229                                 /* nothing */;
 230                         /* Go .. */
 231                         ticks = jiffies;
 232                         __delay(loops_per_jiffy);
 233                         ticks = jiffies - ticks;
 234                         if (ticks)
 235                                 break;
 236                 }
 237
 238                 /*
 239                  * Do a binary approximation to get loops_per_jiffy set to
 240                  * equal one clock (up to lps_precision bits)
 241                  */
 242                 loops_per_jiffy >>= 1;
 243                 loopbit = loops_per_jiffy;
 244                 while (lps_precision-- && (loopbit >>= 1)) {
 245                         loops_per_jiffy |= loopbit;
 246                         ticks = jiffies;
 247                         while (ticks == jiffies)
 248                                 /* nothing */;
 249                         ticks = jiffies;
 250                         __delay(loops_per_jiffy);
 251                         if (jiffies != ticks)   /* longer than 1 tick */
 252                                 loops_per_jiffy &= ~loopbit;
 253                 }
 254
 255                 /* Round the value and print it */
 256                 printk("%lu.%02lu BogoMIPS (lpj=%lu)\n",
 257                         loops_per_jiffy/(500000/HZ),
 258                         (loops_per_jiffy/(5000/HZ)) % 100,
 259                         loops_per_jiffy);
 260         }
 261
 262 }
 263
 264 static int __init debug_kernel(char *str)
 265 {
 266         if (*str)
 267                 return 0;
 268         console_loglevel = 10;
 269         return 1;
 270 }
 271
 272 static int __init quiet_kernel(char *str)
 273 {
 274         if (*str)
 275                 return 0;
 276         console_loglevel = 4;
 277         return 1;
 278 }
 279
 280 __setup("debug", debug_kernel);
 281 __setup("quiet", quiet_kernel);
 282
 283 /*
 284  * Unknown boot options get handed to init, unless they look like
 285  * failed parameters
 286  */
 287 static int __init unknown_bootoption(char *param, char *val)
 288 {
 289         /* Change NUL term back to "=", to make "param" the whole string. */
 290         if (val) {
 291                 /* param=val or param="val"? */
 292                 if (val == param+strlen(param)+1)
 293                         val[-1] = '=';
 294                 else if (val == param+strlen(param)+2) {
 295                         val[-2] = '=';
 296                         memmove(val-1, val, strlen(val)+1);
 297                         val--;
 298                 } else
 299                         BUG();
 300         }
 301
 302         /* Handle obsolete-style parameters */
 303         if (obsolete_checksetup(param))
 304                 return 0;
 305
 306         /*
 307          * Preemptive maintenance for "why didn't my mispelled command
 308          * line work?"
 309          */
 310         if (strchr(param, '.') && (!val || strchr(param, '.') < val)) {
 311                 printk(KERN_ERR "Unknown boot option `%s': ignoring\n", param);
 312                 return 0;
 313         }
 314
 315         if (panic_later)
 316                 return 0;
 317
 318         if (val) {
 319                 /* Environment option */
 320                 unsigned int i;
 321                 for (i = 0; envp_init[i]; i++) {
 322                         if (i == MAX_INIT_ENVS) {
 323                                 panic_later = "Too many boot env vars at `%s'";
 324                                 panic_param = param;
 325                         }
 326                         if (!strncmp(param, envp_init[i], val - param))
 327                                 break;
 328                 }
 329                 envp_init[i] = param;
 330         } else {
 331                 /* Command line option */
 332                 unsigned int i;
 333                 for (i = 0; argv_init[i]; i++) {
 334                         if (i == MAX_INIT_ARGS) {
 335                                 panic_later = "Too many boot init vars at `%s'";
 336                                 panic_param = param;
 337                         }
 338                 }
 339                 argv_init[i] = param;
 340         }
 341         return 0;
 342 }
 343
 344 static int __init init_setup(char *str)
 345 {
 346         unsigned int i;
 347
 348         execute_command = str;
 349         /*
 350          * In case LILO is going to boot us with default command line,
 351          * it prepends "auto" before the whole cmdline which makes
 352          * the shell think it should execute a script with such name.
 353          * So we ignore all arguments entered _before_ init=... [MJ]
 354          */
 355         for (i = 1; i < MAX_INIT_ARGS; i++)
 356                 argv_init[i] = NULL;
 357         return 1;
 358 }
 359 __setup("init=", init_setup);
 360
 361 extern void setup_arch(char **);
 362 extern void cpu_idle(void);
 363
 364 #ifndef CONFIG_SMP
 365
 366 #ifdef CONFIG_X86_LOCAL_APIC
 367 static void __init smp_init(void)
 368 {
 369         APIC_init_uniprocessor();
 370 }
 371 #else
 372 #define smp_init()      do { } while (0)
 373 #endif
 374
 375 static inline void setup_per_cpu_areas(void) { }
 376 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 377
 378 #else
 379
 380 #ifdef __GENERIC_PER_CPU
 381 unsigned long __per_cpu_offset[NR_CPUS];
 382
 383 EXPORT_SYMBOL(__per_cpu_offset);
 384
 385 static void __init setup_per_cpu_areas(void)
 386 {
 387         unsigned long size, i;
 388         char *ptr;
 389         /* Created by linker magic */
 390         extern char __per_cpu_start[], __per_cpu_end[];
 391
 392         /* Copy section for each CPU (we discard the original) */
 393         size = ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES);
 394 #ifdef CONFIG_MODULES
 395         if (size < PERCPU_ENOUGH_ROOM)
 396                 size = PERCPU_ENOUGH_ROOM;
 397 #endif
 398
 399         ptr = alloc_bootmem(size * NR_CPUS);
 400
 401         for (i = 0; i < NR_CPUS; i++, ptr += size) {
 402                 __per_cpu_offset[i] = ptr - __per_cpu_start;
 403                 memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
 404         }
 405 }
 406 #endif /* !__GENERIC_PER_CPU */
 407
 408 /* Called by boot processor to activate the rest. */
 409 static void __init smp_init(void)
 410 {
 411         unsigned int i;
 412
 413         /* FIXME: This should be done in userspace --RR */
 414         for_each_present_cpu(i) {
 415                 if (num_online_cpus() >= max_cpus)
 416                         break;
 417                 if (!cpu_online(i))
 418                         cpu_up(i);
 419         }
 420
 421         /* Any cleanup work */
 422         printk("Brought up %ld CPUs\n", (long)num_online_cpus());
 423         smp_cpus_done(max_cpus);
 424 #if 0
 425         /* Get other processors into their bootup holding patterns. */
 426
 427         smp_threads_ready=1;
 428         smp_commence();
 429 #endif
 430 }
 431
 432 #endif
 433
 434 /*
 435  * We need to finalize in a non-__init function or else race conditions
 436  * between the root thread and the init thread may cause start_kernel to
 437  * be reaped by free_initmem before the root thread has proceeded to
 438  * cpu_idle.
 439  *
 440  * gcc-3.4 accidentally inlines this function, so use noinline.
 441  */
 442
 443 static void noinline rest_init(void)
 444         __releases(kernel_lock)
 445 {
 446         kernel_thread(init, NULL, CLONE_FS | CLONE_SIGHAND);
 447         numa_default_policy();
 448         unlock_kernel();
 449         cpu_idle();
 450 }
 451
 452 /* Check for early params. */
 453 static int __init do_early_param(char *param, char *val)
 454 {
 455         struct obs_kernel_param *p;
 456         extern struct obs_kernel_param __setup_start, __setup_end;
 457
 458         for (p = &__setup_start; p < &__setup_end; p++) {
 459                 if (p->early && strcmp(param, p->str) == 0) {
 460                         if (p->setup_func(val) != 0)
 461                                 printk(KERN_WARNING
 462                                        "Malformed early option '%s'\n", param);
 463                 }
 464         }
 465         /* We accept everything at this stage. */
 466         return 0;
 467 }
 468
 469 /* Arch code calls this early on, or if not, just before other parsing. */
 470 void __init parse_early_param(void)
 471 {
 472         static __initdata int done = 0;
 473         static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
 474
 475         if (done)
 476                 return;
 477
 478         /* All fall through to do_early_param. */
 479         strlcpy(tmp_cmdline, saved_command_line, COMMAND_LINE_SIZE);
 480         parse_args("early options", tmp_cmdline, NULL, 0, do_early_param);
 481         done = 1;
 482 }
 483
 484 /*
 485  *      Activate the first processor.
 486  */
 487
 488 asmlinkage void __init start_kernel(void)
 489 {
 490         char * command_line;
 491         extern struct kernel_param __start___param[], __stop___param[];
 492 /*
 493  * Interrupts are still disabled. Do necessary setups, then
 494  * enable them
 495  */
 496         lock_kernel();
 497         page_address_init();
 498         printk(linux_banner);
 499         setup_arch(&command_line);
 500         setup_per_cpu_areas();
 501
 502         /*
 503          * Mark the boot cpu "online" so that it can call console drivers in
 504          * printk() and can access its per-cpu storage.
 505          */
 506         smp_prepare_boot_cpu();
 507
 508         /*
 509          * Set up the scheduler prior starting any interrupts (such as the
 510          * timer interrupt). Full topology setup happens at smp_init()
 511          * time - but meanwhile we still have a functioning scheduler.
 512          */
 513         sched_init();
 514         build_all_zonelists();
 515         page_alloc_init();
 516         printk("Kernel command line: %s\n", saved_command_line);
 517         parse_early_param();
 518         parse_args("Booting kernel", command_line, __start___param,
 519                    __stop___param - __start___param,
 520                    &unknown_bootoption);
 521         sort_main_extable();
 522         trap_init();
 523         rcu_init();
 524         init_IRQ();
 525         pidhash_init();
 526         init_timers();
 527         softirq_init();
 528         time_init();
 529
 530         /*
 531          * HACK ALERT! This is early. We're enabling the console before
 532          * we've done PCI setups etc, and console_init() must be aware of
 533          * this. But we do want output early, in case something goes wrong.
 534          */
 535         console_init();
 536         if (panic_later)
 537                 panic(panic_later, panic_param);
 538         profile_init();
 539         local_irq_enable();
 540 #ifdef CONFIG_BLK_DEV_INITRD
 541         if (initrd_start && !initrd_below_start_ok &&
 542                         initrd_start < min_low_pfn << PAGE_SHIFT) {
 543                 printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
 544                     "disabling it.\n",initrd_start,min_low_pfn << PAGE_SHIFT);
 545                 initrd_start = 0;
 546         }
 547 #endif
 548         vfs_caches_init_early();
 549         mem_init();
 550         kmem_cache_init();
 551         numa_policy_init();
 552         if (late_time_init)
 553                 late_time_init();
 554         calibrate_delay();
 555         pidmap_init();
 556         pgtable_cache_init();
 557         prio_tree_init();
 558         anon_vma_init();
 559 #ifdef CONFIG_X86
 560         if (efi_enabled)
 561                 efi_enter_virtual_mode();
 562 #endif
 563         fork_init(num_physpages);
 564         proc_caches_init();
 565         buffer_init();
 566         unnamed_dev_init();
 567         security_init();
 568         vfs_caches_init(num_physpages);
 569         radix_tree_init();
 570         signals_init();
 571         /* rootfs populating might need page-writeback */
 572         page_writeback_init();
 573 #ifdef CONFIG_PROC_FS
 574         proc_root_init();
 575 #endif
 576         check_bugs();
 577
 578         acpi_early_init(); /* before LAPIC and SMP init */
 579
 580         /* Do the rest non-__init'ed, we're now alive */
 581         rest_init();
 582 }
 583
 584 static int __initdata initcall_debug;
 585
 586 static int __init initcall_debug_setup(char *str)
 587 {
 588         initcall_debug = 1;
 589         return 1;
 590 }
 591 __setup("initcall_debug", initcall_debug_setup);
 592
 593 struct task_struct *child_reaper = &init_task;
 594
 595 extern initcall_t __initcall_start, __initcall_end;
 596
 597 static void __init do_initcalls(void)
 598 {
 599         initcall_t *call;
 600         int count = preempt_count();
 601
 602         for (call = &__initcall_start; call < &__initcall_end; call++) {
 603                 char *msg;
 604
 605                 if (initcall_debug) {
 606                         printk(KERN_DEBUG "Calling initcall 0x%p", *call);
 607                         print_fn_descriptor_symbol(": %s()", (unsigned long) *call);
 608                         printk("\n");
 609                 }
 610
 611                 (*call)();
 612
 613                 msg = NULL;
 614                 if (preempt_count() != count) {
 615                         msg = "preemption imbalance";
 616                         preempt_count() = count;
 617                 }
 618                 if (irqs_disabled()) {
 619                         msg = "disabled interrupts";
 620                         local_irq_enable();
 621                 }
 622                 if (msg) {
 623                         printk("error in initcall at 0x%p: "
 624                                 "returned with %s\n", *call, msg);
 625                 }
 626         }
 627
 628         /* Make sure there is no pending stuff from the initcall sequence */
 629         flush_scheduled_work();
 630 }
 631
 632 /*
 633  * Ok, the machine is now initialized. None of the devices
 634  * have been touched yet, but the CPU subsystem is up and
 635  * running, and memory and process management works.
 636  *
 637  * Now we can finally start doing some real work..
 638  */
 639 static void __init do_basic_setup(void)
 640 {
 641         /* drivers will send hotplug events */
 642         init_workqueues();
 643         usermodehelper_init();
 644         key_init();
 645         driver_init();
 646
 647 #ifdef CONFIG_SYSCTL
 648         sysctl_init();
 649 #endif
 650
 651         /* Networking initialization needs a process context */
 652         sock_init();
 653
 654         do_initcalls();
 655 }
 656
 657 static void do_pre_smp_initcalls(void)
 658 {
 659         extern int spawn_ksoftirqd(void);
 660 #ifdef CONFIG_SMP
 661         extern int migration_init(void);
 662
 663         migration_init();
 664 #endif
 665         spawn_ksoftirqd();
 666 }
 667
 668 static void run_init_process(char *init_filename)
 669 {
 670         argv_init[0] = init_filename;
 671         execve(init_filename, argv_init, envp_init);
 672 }
 673
 674 static inline void fixup_cpu_present_map(void)
 675 {
 676 #ifdef CONFIG_SMP
 677         int i;
 678
 679         /*
 680          * If arch is not hotplug ready and did not populate
 681          * cpu_present_map, just make cpu_present_map same as cpu_possible_map
 682          * for other cpu bringup code to function as normal. e.g smp_init() etc.
 683          */
 684         if (cpus_empty(cpu_present_map)) {
 685                 for_each_cpu(i) {
 686                         cpu_set(i, cpu_present_map);
 687                 }
 688         }
 689 #endif
 690 }
 691
 692 static int init(void * unused)
 693 {
 694         lock_kernel();
 695         /*
 696          * Tell the world that we're going to be the grim
 697          * reaper of innocent orphaned children.
 698          *
 699          * We don't want people to have to make incorrect
 700          * assumptions about where in the task array this
 701          * can be found.
 702          */
 703         child_reaper = current;
 704
 705         /* Sets up cpus_possible() */
 706         smp_prepare_cpus(max_cpus);
 707
 708         do_pre_smp_initcalls();
 709
 710         fixup_cpu_present_map();
 711         smp_init();
 712         sched_init_smp();
 713
 714         /*
 715          * Do this before initcalls, because some drivers want to access
 716          * firmware files.
 717          */
 718         populate_rootfs();
 719
 720         do_basic_setup();
 721
 722         /*
 723          * check if there is an early userspace init.  If yes, let it do all
 724          * the work
 725          */
 726         if (sys_access((const char __user *) "/init", 0) == 0)
 727                 execute_command = "/init";
 728         else
 729                 prepare_namespace();
 730
 731         /*
 732          * Ok, we have completed the initial bootup, and
 733          * we're essentially up and running. Get rid of the
 734          * initmem segments and start the user-mode stuff..
 735          */
 736         free_initmem();
 737         unlock_kernel();
 738         system_state = SYSTEM_RUNNING;
 739         numa_default_policy();
 740
 741         if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
 742                 printk("Warning: unable to open an initial console.\n");
 743
 744         (void) sys_dup(0);
 745         (void) sys_dup(0);
 746
 747         /*
 748          * We try each of these until one succeeds.
 749          *
 750          * The Bourne shell can be used instead of init if we are
 751          * trying to recover a really broken machine.
 752          */
 753
 754         if (execute_command)
 755                 run_init_process(execute_command);
 756
 757         run_init_process("/sbin/init");
 758         run_init_process("/etc/init");
 759         run_init_process("/bin/init");
 760         run_init_process("/bin/sh");
 761
 762         panic("No init found.  Try passing init= option to kernel.");
 763 }
 764
 765 static int early_param_test(char *rest)
 766 {
 767         printk("early_parm_test: %s\n", rest ?: "(null)");
 768         return rest ? 0 : -EINVAL;
 769 }
 770 early_param("testsetup", early_param_test);
 771 static int early_setup_test(char *rest)
 772 {
 773         printk("early_setup_test: %s\n", rest ?: "(null)");
 774         return 0;
 775 }
 776 __setup("testsetup_long", early_setup_test);