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/proc_fs.h>
  16 #include <linux/devfs_fs_kernel.h>
  17 #include <linux/unistd.h>
  18 #include <linux/string.h>
  19 #include <linux/ctype.h>
  20 #include <linux/delay.h>
  21 #include <linux/utsname.h>
  22 #include <linux/ioport.h>
  23 #include <linux/init.h>
  24 #include <linux/raid/md.h>
  25 #include <linux/smp_lock.h>
  26 #include <linux/blk.h>
  27 #include <linux/hdreg.h>
  28 #include <linux/iobuf.h>
  29 #include <linux/bootmem.h>
  30
  31 #include <asm/io.h>
  32 #include <asm/bugs.h>
  33
  34 #ifdef CONFIG_PCI
  35 #include <linux/pci.h>
  36 #endif
  37
  38 #ifdef CONFIG_DIO
  39 #include <linux/dio.h>
  40 #endif
  41
  42 #ifdef CONFIG_ZORRO
  43 #include <linux/zorro.h>
  44 #endif
  45
  46 #ifdef CONFIG_MTRR
  47 #  include <asm/mtrr.h>
  48 #endif
  49
  50 #ifdef CONFIG_3215_CONSOLE
  51 extern int con3215_activate(void);
  52 #endif
  53
  54 #ifdef CONFIG_MAC
  55 extern void nubus_init(void);
  56 #endif
  57
  58 #ifdef CONFIG_ISAPNP
  59 #include <linux/isapnp.h>
  60 #endif
  61
  62 #ifdef CONFIG_IRDA
  63 #include <net/irda/irda_device.h>
  64 #endif
  65
  66 #ifdef CONFIG_X86_IO_APIC
  67 #include <asm/smp.h>
  68 #endif
  69
  70 /*
  71  * Versions of gcc older than that listed below may actually compile
  72  * and link okay, but the end product can have subtle run time bugs.
  73  * To avoid associated bogus bug reports, we flatly refuse to compile
  74  * with a gcc that is known to be too old from the very beginning.
  75  */
  76 #if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7)
  77 #error sorry, your GCC is too old. It builds incorrect kernels.
  78 #endif
  79
  80 extern char _stext, _etext;
  81 extern char *linux_banner;
  82
  83 extern int console_loglevel;
  84
  85 static int init(void *);
  86
  87 extern void init_IRQ(void);
  88 extern void init_modules(void);
  89 extern void sock_init(void);
  90 extern void fork_init(unsigned long);
  91 extern void mca_init(void);
  92 extern void sbus_init(void);
  93 extern void ppc_init(void);
  94 extern void sysctl_init(void);
  95 extern void signals_init(void);
  96 extern void bdev_init(void);
  97 extern int init_pcmcia_ds(void);
  98 extern int usb_init(void);
  99
 100 extern void free_initmem(void);
 101 extern void filesystem_setup(void);
 102
 103 #ifdef CONFIG_TC
 104 extern void tc_init(void);
 105 #endif
 106
 107 extern void ecard_init(void);
 108
 109 #if defined(CONFIG_SYSVIPC)
 110 extern void ipc_init(void);
 111 #endif
 112 #if defined(CONFIG_QUOTA)
 113 extern void dquot_init_hash(void);
 114 #endif
 115
 116 /*
 117  * Boot command-line arguments
 118  */
 119 #define MAX_INIT_ARGS 8
 120 #define MAX_INIT_ENVS 8
 121
 122 extern void time_init(void);
 123 extern void softirq_init(void);
 124
 125 int rows, cols;
 126
 127 #ifdef CONFIG_BLK_DEV_INITRD
 128 kdev_t real_root_dev;
 129 #endif
 130
 131 int root_mountflags = MS_RDONLY;
 132 char *execute_command;
 133 char root_device_name[64];
 134
 135
 136 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 137 static char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 138
 139 static int __init profile_setup(char *str)
 140 {
 141     int par;
 142     if (get_option(&str,&par)) prof_shift = par;
 143         return 1;
 144 }
 145
 146 __setup("profile=", profile_setup);
 147
 148
 149 static struct dev_name_struct {
 150         const char *name;
 151         const int num;
 152 } root_dev_names[] __initdata = {
 153         { "nfs",     0x00ff },
 154         { "hda",     0x0300 },
 155         { "hdb",     0x0340 },
 156         { "hdc",     0x1600 },
 157         { "hdd",     0x1640 },
 158         { "hde",     0x2100 },
 159         { "hdf",     0x2140 },
 160         { "hdg",     0x2200 },
 161         { "hdh",     0x2240 },
 162         { "hdi",     0x3800 },
 163         { "hdj",     0x3840 },
 164         { "hdk",     0x3900 },
 165         { "hdl",     0x3940 },
 166         { "hdm",     0x5800 },
 167         { "hdn",     0x5840 },
 168         { "hdo",     0x5900 },
 169         { "hdp",     0x5940 },
 170         { "hdq",     0x5A00 },
 171         { "hdr",     0x5A40 },
 172         { "hds",     0x5B00 },
 173         { "hdt",     0x5B40 },
 174         { "sda",     0x0800 },
 175         { "sdb",     0x0810 },
 176         { "sdc",     0x0820 },
 177         { "sdd",     0x0830 },
 178         { "sde",     0x0840 },
 179         { "sdf",     0x0850 },
 180         { "sdg",     0x0860 },
 181         { "sdh",     0x0870 },
 182         { "sdi",     0x0880 },
 183         { "sdj",     0x0890 },
 184         { "sdk",     0x08a0 },
 185         { "sdl",     0x08b0 },
 186         { "sdm",     0x08c0 },
 187         { "sdn",     0x08d0 },
 188         { "sdo",     0x08e0 },
 189         { "sdp",     0x08f0 },
 190         { "ada",     0x1c00 },
 191         { "adb",     0x1c10 },
 192         { "adc",     0x1c20 },
 193         { "add",     0x1c30 },
 194         { "ade",     0x1c40 },
 195         { "fd",      0x0200 },
 196         { "md",      0x0900 },
 197         { "xda",     0x0d00 },
 198         { "xdb",     0x0d40 },
 199         { "ram",     0x0100 },
 200         { "scd",     0x0b00 },
 201         { "mcd",     0x1700 },
 202         { "cdu535",  0x1800 },
 203         { "sonycd",  0x1800 },
 204         { "aztcd",   0x1d00 },
 205         { "cm206cd", 0x2000 },
 206         { "gscd",    0x1000 },
 207         { "sbpcd",   0x1900 },
 208         { "eda",     0x2400 },
 209         { "edb",     0x2440 },
 210         { "pda",        0x2d00 },
 211         { "pdb",        0x2d10 },
 212         { "pdc",        0x2d20 },
 213         { "pdd",        0x2d30 },
 214         { "pcd",        0x2e00 },
 215         { "pf",         0x2f00 },
 216         { "apblock", APBLOCK_MAJOR << 8},
 217         { "ddv", DDV_MAJOR << 8},
 218         { "jsfd",    JSFD_MAJOR << 8},
 219 #ifdef CONFIG_MDISK
 220         { "mnda", (MDISK_MAJOR << MINORBITS)},
 221         { "mndb", (MDISK_MAJOR << MINORBITS) + 1},
 222         { "mndc", (MDISK_MAJOR << MINORBITS) + 2},
 223         { "mndd", (MDISK_MAJOR << MINORBITS) + 3},
 224         { "mnde", (MDISK_MAJOR << MINORBITS) + 4},
 225         { "mndf", (MDISK_MAJOR << MINORBITS) + 5},
 226         { "mndg", (MDISK_MAJOR << MINORBITS) + 6},
 227         { "mndh", (MDISK_MAJOR << MINORBITS) + 7},
 228 #endif
 229 #ifdef CONFIG_DASD
 230         { "dasda", (DASD_MAJOR << MINORBITS) },
 231         { "dasdb", (DASD_MAJOR << MINORBITS) + (1 << 2) },
 232         { "dasdc", (DASD_MAJOR << MINORBITS) + (2 << 2) },
 233         { "dasdd", (DASD_MAJOR << MINORBITS) + (3 << 2) },
 234         { "dasde", (DASD_MAJOR << MINORBITS) + (4 << 2) },
 235         { "dasdf", (DASD_MAJOR << MINORBITS) + (5 << 2) },
 236         { "dasdg", (DASD_MAJOR << MINORBITS) + (6 << 2) },
 237         { "dasdh", (DASD_MAJOR << MINORBITS) + (7 << 2) },
 238 #endif
 239 #if defined(CONFIG_BLK_CPQ_DA) || defined(CONFIG_BLK_CPQ_DA_MODULE)
 240         { "ida/c0d0p",0x4800 },
 241         { "ida/c0d1p",0x4810 },
 242         { "ida/c0d2p",0x4820 },
 243         { "ida/c0d3p",0x4830 },
 244         { "ida/c0d4p",0x4840 },
 245         { "ida/c0d5p",0x4850 },
 246         { "ida/c0d6p",0x4860 },
 247         { "ida/c0d7p",0x4870 },
 248         { "ida/c0d8p",0x4880 },
 249         { "ida/c0d9p",0x4890 },
 250         { "ida/c0d10p",0x48A0 },
 251         { "ida/c0d11p",0x48B0 },
 252         { "ida/c0d12p",0x48C0 },
 253         { "ida/c0d13p",0x48D0 },
 254         { "ida/c0d14p",0x48E0 },
 255         { "ida/c0d15p",0x48F0 },
 256 #endif
 257
 258         { NULL, 0 }
 259 };
 260
 261 kdev_t __init name_to_kdev_t(char *line)
 262 {
 263         int base = 0;
 264
 265         if (strncmp(line,"/dev/",5) == 0) {
 266                 struct dev_name_struct *dev = root_dev_names;
 267                 line += 5;
 268                 do {
 269                         int len = strlen(dev->name);
 270                         if (strncmp(line,dev->name,len) == 0) {
 271                                 line += len;
 272                                 base = dev->num;
 273                                 break;
 274                         }
 275                         dev++;
 276                 } while (dev->name);
 277         }
 278         return to_kdev_t(base + simple_strtoul(line,NULL,base?10:16));
 279 }
 280
 281 static int __init root_dev_setup(char *line)
 282 {
 283         int i;
 284         char ch;
 285
 286         ROOT_DEV = name_to_kdev_t(line);
 287         memset (root_device_name, 0, sizeof root_device_name);
 288         if (strncmp (line, "/dev/", 5) == 0) line += 5;
 289         for (i = 0; i < sizeof root_device_name - 1; ++i)
 290         {
 291             ch = line[i];
 292             if ( isspace (ch) || (ch == ',') || (ch == '\0') ) break;
 293             root_device_name[i] = ch;
 294         }
 295         return 1;
 296 }
 297
 298 __setup("root=", root_dev_setup);
 299
 300 static int __init checksetup(char *line)
 301 {
 302         struct kernel_param *p;
 303
 304         p = &__setup_start;
 305         do {
 306                 int n = strlen(p->str);
 307                 if (!strncmp(line,p->str,n)) {
 308                         if (p->setup_func(line+n))
 309                                 return 1;
 310                 }
 311                 p++;
 312         } while (p < &__setup_end);
 313         return 0;
 314 }
 315
 316 /* this should be approx 2 Bo*oMips to start (note initial shift), and will
 317    still work even if initially too large, it will just take slightly longer */
 318 unsigned long loops_per_sec = (1<<12);
 319
 320 /* This is the number of bits of precision for the loops_per_second.  Each
 321    bit takes on average 1.5/HZ seconds.  This (like the original) is a little
 322    better than 1% */
 323 #define LPS_PREC 8
 324
 325 void __init calibrate_delay(void)
 326 {
 327         unsigned long ticks, loopbit;
 328         int lps_precision = LPS_PREC;
 329
 330         loops_per_sec = (1<<12);
 331
 332         printk("Calibrating delay loop... ");
 333         while (loops_per_sec <<= 1) {
 334                 /* wait for "start of" clock tick */
 335                 ticks = jiffies;
 336                 while (ticks == jiffies)
 337                         /* nothing */;
 338                 /* Go .. */
 339                 ticks = jiffies;
 340                 __delay(loops_per_sec);
 341                 ticks = jiffies - ticks;
 342                 if (ticks)
 343                         break;
 344         }
 345
 346 /* Do a binary approximation to get loops_per_second set to equal one clock
 347    (up to lps_precision bits) */
 348         loops_per_sec >>= 1;
 349         loopbit = loops_per_sec;
 350         while ( lps_precision-- && (loopbit >>= 1) ) {
 351                 loops_per_sec |= loopbit;
 352                 ticks = jiffies;
 353                 while (ticks == jiffies);
 354                 ticks = jiffies;
 355                 __delay(loops_per_sec);
 356                 if (jiffies != ticks)   /* longer than 1 tick */
 357                         loops_per_sec &= ~loopbit;
 358         }
 359
 360 /* finally, adjust loops per second in terms of seconds instead of clocks */
 361         loops_per_sec *= HZ;
 362 /* Round the value and print it */
 363         printk("%lu.%02lu BogoMIPS\n",
 364                 (loops_per_sec+2500)/500000,
 365                 ((loops_per_sec+2500)/5000) % 100);
 366 }
 367
 368 static int __init readonly(char *str)
 369 {
 370         if (*str)
 371                 return 0;
 372         root_mountflags |= MS_RDONLY;
 373         return 1;
 374 }
 375
 376 static int __init readwrite(char *str)
 377 {
 378         if (*str)
 379                 return 0;
 380         root_mountflags &= ~MS_RDONLY;
 381         return 1;
 382 }
 383
 384 static int __init debug_kernel(char *str)
 385 {
 386         if (*str)
 387                 return 0;
 388         console_loglevel = 10;
 389         return 1;
 390 }
 391
 392 static int __init quiet_kernel(char *str)
 393 {
 394         if (*str)
 395                 return 0;
 396         console_loglevel = 4;
 397         return 1;
 398 }
 399
 400 __setup("ro", readonly);
 401 __setup("rw", readwrite);
 402 __setup("debug", debug_kernel);
 403 __setup("quiet", quiet_kernel);
 404
 405 /*
 406  * This is a simple kernel command line parsing function: it parses
 407  * the command line, and fills in the arguments/environment to init
 408  * as appropriate. Any cmd-line option is taken to be an environment
 409  * variable if it contains the character '='.
 410  *
 411  * This routine also checks for options meant for the kernel.
 412  * These options are not given to init - they are for internal kernel use only.
 413  */
 414 static void __init parse_options(char *line)
 415 {
 416         char *next,*quote;
 417         int args, envs;
 418
 419         if (!*line)
 420                 return;
 421         args = 0;
 422         envs = 1;       /* TERM is set to 'linux' by default */
 423         next = line;
 424         while ((line = next) != NULL) {
 425                 quote = strchr(line,'"');
 426                 next = strchr(line, ' ');
 427                 while (next != NULL && quote != NULL && quote < next) {
 428                         /* we found a left quote before the next blank
 429                          * now we have to find the matching right quote
 430                          */
 431                         next = strchr(quote+1, '"');
 432                         if (next != NULL) {
 433                                 quote = strchr(next+1, '"');
 434                                 next = strchr(next+1, ' ');
 435                         }
 436                 }
 437                 if (next != NULL)
 438                         *next++ = 0;
 439                 if (!strncmp(line,"init=",5)) {
 440                         line += 5;
 441                         execute_command = line;
 442                         /* In case LILO is going to boot us with default command line,
 443                          * it prepends "auto" before the whole cmdline which makes
 444                          * the shell think it should execute a script with such name.
 445                          * So we ignore all arguments entered _before_ init=... [MJ]
 446                          */
 447                         args = 0;
 448                         continue;
 449                 }
 450                 if (checksetup(line))
 451                         continue;
 452
 453                 /*
 454                  * Then check if it's an environment variable or
 455                  * an option.
 456                  */
 457                 if (strchr(line,'=')) {
 458                         if (envs >= MAX_INIT_ENVS)
 459                                 break;
 460                         envp_init[++envs] = line;
 461                 } else {
 462                         if (args >= MAX_INIT_ARGS)
 463                                 break;
 464                         if (*line)
 465                                 argv_init[++args] = line;
 466                 }
 467         }
 468         argv_init[args+1] = NULL;
 469         envp_init[envs+1] = NULL;
 470 }
 471
 472
 473 extern void setup_arch(char **);
 474 extern void cpu_idle(void);
 475
 476 #ifndef CONFIG_SMP
 477
 478 #ifdef CONFIG_X86_IO_APIC
 479 static void __init smp_init(void)
 480 {
 481         IO_APIC_init_uniprocessor();
 482 }
 483 #else
 484 #define smp_init()      do { } while (0)
 485 #endif
 486
 487 #else
 488
 489 /* Called by boot processor to activate the rest. */
 490 static void __init smp_init(void)
 491 {
 492         /* Get other processors into their bootup holding patterns. */
 493         smp_boot_cpus();
 494         smp_threads_ready=1;
 495         smp_commence();
 496 }
 497
 498 #endif
 499
 500 /*
 501  *      Activate the first processor.
 502  */
 503
 504 asmlinkage void __init start_kernel(void)
 505 {
 506         char * command_line;
 507         unsigned long mempages;
 508         extern char saved_command_line[];
 509 /*
 510  * Interrupts are still disabled. Do necessary setups, then
 511  * enable them
 512  */
 513         lock_kernel();
 514         printk(linux_banner);
 515         setup_arch(&command_line);
 516         printk("Kernel command line: %s\n", saved_command_line);
 517         parse_options(command_line);
 518         trap_init();
 519         init_IRQ();
 520         sched_init();
 521         time_init();
 522         softirq_init();
 523
 524         /*
 525          * HACK ALERT! This is early. We're enabling the console before
 526          * we've done PCI setups etc, and console_init() must be aware of
 527          * this. But we do want output early, in case something goes wrong.
 528          */
 529         console_init();
 530 #ifdef CONFIG_MODULES
 531         init_modules();
 532 #endif
 533         if (prof_shift) {
 534                 unsigned int size;
 535                 /* only text is profiled */
 536                 prof_len = (unsigned long) &_etext - (unsigned long) &_stext;
 537                 prof_len >>= prof_shift;
 538
 539                 size = prof_len * sizeof(unsigned int) + PAGE_SIZE-1;
 540                 prof_buffer = (unsigned int *) alloc_bootmem(size);
 541         }
 542
 543         kmem_cache_init();
 544         sti();
 545         calibrate_delay();
 546 #ifdef CONFIG_BLK_DEV_INITRD
 547         if (initrd_start && !initrd_below_start_ok &&
 548                         initrd_start < min_low_pfn << PAGE_SHIFT) {
 549                 printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
 550                     "disabling it.\n",initrd_start,min_low_pfn << PAGE_SHIFT);
 551                 initrd_start = 0;
 552         }
 553 #endif
 554         mem_init();
 555         kmem_cache_sizes_init();
 556 #ifdef CONFIG_3215_CONSOLE
 557         con3215_activate();
 558 #endif
 559 #ifdef CONFIG_PROC_FS
 560         proc_root_init();
 561 #endif
 562         mempages = num_physpages;
 563
 564         fork_init(mempages);
 565         vfs_caches_init(mempages);
 566         vma_init();
 567         buffer_init(mempages);
 568         page_cache_init(mempages);
 569         kiobuf_setup();
 570         signals_init();
 571         bdev_init();
 572         inode_init(mempages);
 573 #if defined(CONFIG_SYSVIPC)
 574         ipc_init();
 575 #endif
 576 #if defined(CONFIG_QUOTA)
 577         dquot_init_hash();
 578 #endif
 579         check_bugs();
 580         printk("POSIX conformance testing by UNIFIX\n");
 581
 582         /*
 583          *      We count on the initial thread going ok
 584          *      Like idlers init is an unlocked kernel thread, which will
 585          *      make syscalls (and thus be locked).
 586          */
 587         smp_init();
 588         kernel_thread(init, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGHAND);
 589         unlock_kernel();
 590         current->need_resched = 1;
 591         cpu_idle();
 592 }
 593
 594 #ifdef CONFIG_BLK_DEV_INITRD
 595 static int do_linuxrc(void * shell)
 596 {
 597         static char *argv[] = { "linuxrc", NULL, };
 598
 599         close(0);close(1);close(2);
 600         setsid();
 601         (void) open("/dev/console",O_RDWR,0);
 602         (void) dup(0);
 603         (void) dup(0);
 604         return execve(shell, argv, envp_init);
 605 }
 606
 607 #endif
 608
 609 struct task_struct *child_reaper = &init_task;
 610
 611 static void __init do_initcalls(void)
 612 {
 613         initcall_t *call;
 614
 615         call = &__initcall_start;
 616         do {
 617                 (*call)();
 618                 call++;
 619         } while (call < &__initcall_end);
 620 }
 621
 622 /*
 623  * Ok, the machine is now initialized. None of the devices
 624  * have been touched yet, but the CPU subsystem is up and
 625  * running, and memory and process management works.
 626  *
 627  * Now we can finally start doing some real work..
 628  */
 629 static void __init do_basic_setup(void)
 630 {
 631 #ifdef CONFIG_BLK_DEV_INITRD
 632         int real_root_mountflags;
 633 #endif
 634
 635         /*
 636          * Tell the world that we're going to be the grim
 637          * reaper of innocent orphaned children.
 638          *
 639          * We don't want people to have to make incorrect
 640          * assumptions about where in the task array this
 641          * can be found.
 642          */
 643         child_reaper = current;
 644
 645 #if defined(CONFIG_MTRR)        /* Do this after SMP initialization */
 646 /*
 647  * We should probably create some architecture-dependent "fixup after
 648  * everything is up" style function where this would belong better
 649  * than in init/main.c..
 650  */
 651         mtrr_init();
 652 #endif
 653
 654 #ifdef CONFIG_SYSCTL
 655         sysctl_init();
 656 #endif
 657
 658         /*
 659          * Ok, at this point all CPU's should be initialized, so
 660          * we can start looking into devices..
 661          */
 662 #ifdef CONFIG_PCI
 663         pci_init();
 664 #endif
 665 #ifdef CONFIG_SBUS
 666         sbus_init();
 667 #endif
 668 #if defined(CONFIG_PPC)
 669         ppc_init();
 670 #endif
 671 #ifdef CONFIG_MCA
 672         mca_init();
 673 #endif
 674 #ifdef CONFIG_ARCH_ACORN
 675         ecard_init();
 676 #endif
 677 #ifdef CONFIG_ZORRO
 678         zorro_init();
 679 #endif
 680 #ifdef CONFIG_DIO
 681         dio_init();
 682 #endif
 683 #ifdef CONFIG_MAC
 684         nubus_init();
 685 #endif
 686 #ifdef CONFIG_ISAPNP
 687         isapnp_init();
 688 #endif
 689 #ifdef CONFIG_USB
 690         usb_init();     /* Do this before doing initcalls, so that we can make
 691                         usbcore initialize here, and all drivers initialize later */
 692 #endif
 693 #ifdef CONFIG_TC
 694         tc_init();
 695 #endif
 696
 697         /* Networking initialization needs a process context */
 698         sock_init();
 699
 700 #ifdef CONFIG_BLK_DEV_INITRD
 701         real_root_dev = ROOT_DEV;
 702         real_root_mountflags = root_mountflags;
 703         if (initrd_start && mount_initrd) root_mountflags &= ~MS_RDONLY;
 704         else mount_initrd =0;
 705 #endif
 706
 707         do_initcalls();
 708
 709         /* .. filesystems .. */
 710         filesystem_setup();
 711
 712 #ifdef CONFIG_IRDA
 713         irda_device_init(); /* Must be done after protocol initialization */
 714 #endif
 715 #ifdef CONFIG_PCMCIA
 716         init_pcmcia_ds();               /* Do this last */
 717 #endif
 718         /* Mount the root filesystem.. */
 719         mount_root();
 720
 721         mount_devfs_fs ();
 722
 723 #ifdef CONFIG_BLK_DEV_INITRD
 724         root_mountflags = real_root_mountflags;
 725         if (mount_initrd && ROOT_DEV != real_root_dev
 726             && MAJOR(ROOT_DEV) == RAMDISK_MAJOR && MINOR(ROOT_DEV) == 0) {
 727                 int error;
 728                 int i, pid;
 729
 730                 pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
 731                 if (pid>0)
 732                         while (pid != wait(&i));
 733                 if (MAJOR(real_root_dev) != RAMDISK_MAJOR
 734                      || MINOR(real_root_dev) != 0) {
 735 #ifdef CONFIG_BLK_DEV_MD
 736                         md_run_setup();
 737 #endif
 738                         error = change_root(real_root_dev,"/initrd");
 739                         if (error)
 740                                 printk(KERN_ERR "Change root to /initrd: "
 741                                     "error %d\n",error);
 742                 }
 743         }
 744 #endif
 745 }
 746
 747 static int init(void * unused)
 748 {
 749         lock_kernel();
 750         do_basic_setup();
 751
 752         /*
 753          * Ok, we have completed the initial bootup, and
 754          * we're essentially up and running. Get rid of the
 755          * initmem segments and start the user-mode stuff..
 756          */
 757         free_initmem();
 758         unlock_kernel();
 759
 760         if (open("/dev/console", O_RDWR, 0) < 0)
 761                 printk("Warning: unable to open an initial console.\n");
 762
 763         (void) dup(0);
 764         (void) dup(0);
 765
 766         /*
 767          * We try each of these until one succeeds.
 768          *
 769          * The Bourne shell can be used instead of init if we are
 770          * trying to recover a really broken machine.
 771          */
 772
 773         if (execute_command)
 774                 execve(execute_command,argv_init,envp_init);
 775         execve("/sbin/init",argv_init,envp_init);
 776         execve("/etc/init",argv_init,envp_init);
 777         execve("/bin/init",argv_init,envp_init);
 778         execve("/bin/sh",argv_init,envp_init);
 779         panic("No init found.  Try passing init= option to kernel.");
 780 }