init/main.c

/* */
This source file includes following definitions.
get_options
profile_setup
ramdisk_start_setup
load_ramdisk
prompt_ramdisk
checksetup
calibrate_delay
parse_options
cpu_idle
start_secondary
smp_init
smp_begin
start_kernel
printf
do_rc
do_shell
init
   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  */
   8 
   9 #define __KERNEL_SYSCALLS__
  10 #include <stdarg.h>
  11 
  12 #include <asm/system.h>
  13 #include <asm/io.h>
  14 
  15 #include <linux/types.h>
  16 #include <linux/fcntl.h>
  17 #include <linux/config.h>
  18 #include <linux/sched.h>
  19 #include <linux/tty.h>
  20 #include <linux/head.h>
  21 #include <linux/unistd.h>
  22 #include <linux/string.h>
  23 #include <linux/timer.h>
  24 #include <linux/fs.h>
  25 #include <linux/ctype.h>
  26 #include <linux/delay.h>
  27 #include <linux/utsname.h>
  28 #include <linux/ioport.h>
  29 #include <linux/hdreg.h>
  30 #include <linux/mm.h>
  31 #include <linux/major.h>
  32 #ifdef CONFIG_APM
  33 #include <linux/apm_bios.h>
  34 #endif
  35 
  36 #include <asm/bugs.h>
  37 
  38 extern char _stext, _etext;
  39 extern char *linux_banner;
  40 
  41 static char printbuf[1024];
  42 
  43 extern int console_loglevel;
  44 
  45 static int init(void *);
  46 extern int bdflush(void *);
  47 extern int kswapd(void *);
  48 
  49 extern void init_IRQ(void);
  50 extern void init_modules(void);
  51 extern long console_init(long, long);
  52 extern long kmalloc_init(long,long);
  53 extern void sock_init(void);
  54 extern long pci_init(long, long);
  55 extern void sysctl_init(void);
  56 
  57 extern void swap_setup(char *str, int *ints);
  58 extern void buff_setup(char *str, int *ints);
  59 extern void bmouse_setup(char *str, int *ints);
  60 extern void eth_setup(char *str, int *ints);
  61 extern void xd_setup(char *str, int *ints);
  62 extern void floppy_setup(char *str, int *ints);
  63 extern void st_setup(char *str, int *ints);
  64 extern void st0x_setup(char *str, int *ints);
  65 extern void advansys_setup(char *str, int *ints);
  66 extern void tmc8xx_setup(char *str, int *ints);
  67 extern void t128_setup(char *str, int *ints);
  68 extern void pas16_setup(char *str, int *ints);
  69 extern void generic_NCR5380_setup(char *str, int *intr);
  70 extern void aha152x_setup(char *str, int *ints);
  71 extern void aha1542_setup(char *str, int *ints);
  72 extern void aic7xxx_setup(char *str, int *ints);
  73 extern void BusLogic_Setup(char *str, int *ints);
  74 extern void fdomain_setup(char *str, int *ints);
  75 extern void NCR53c406a_setup(char *str, int *ints);
  76 extern void scsi_luns_setup(char *str, int *ints);
  77 extern void sound_setup(char *str, int *ints);
  78 #ifdef CONFIG_CDU31A
  79 extern void cdu31a_setup(char *str, int *ints);
  80 #endif CONFIG_CDU31A
  81 #ifdef CONFIG_MCD
  82 extern void mcd_setup(char *str, int *ints);
  83 #endif CONFIG_MCD
  84 #ifdef CONFIG_MCDX
  85 extern void mcdx_setup(char *str, int *ints);
  86 #endif CONFIG_MCDX
  87 #ifdef CONFIG_SBPCD
  88 extern void sbpcd_setup(char *str, int *ints);
  89 #endif CONFIG_SBPCD
  90 #ifdef CONFIG_AZTCD
  91 extern void aztcd_setup(char *str, int *ints);
  92 #endif CONFIG_AZTCD
  93 #ifdef CONFIG_CDU535
  94 extern void sonycd535_setup(char *str, int *ints);
  95 #endif CONFIG_CDU535
  96 #ifdef CONFIG_GSCD
  97 extern void gscd_setup(char *str, int *ints);
  98 #endif CONFIG_GSCD
  99 #ifdef CONFIG_CM206
 100 extern void cm206_setup(char *str, int *ints);
 101 #endif CONFIG_CM206
 102 #ifdef CONFIG_OPTCD
 103 extern void optcd_setup(char *str, int *ints);
 104 #endif CONFIG_OPTCD
 105 #ifdef CONFIG_SJCD
 106 extern void sjcd_setup(char *str, int *ints);
 107 #endif CONFIG_SJCD
 108 #ifdef CONFIG_BLK_DEV_RAM
 109 static void ramdisk_start_setup(char *str, int *ints);
 110 static void load_ramdisk(char *str, int *ints);
 111 static void prompt_ramdisk(char *str, int *ints);
 112 #endif CONFIG_BLK_DEV_RAM
 113 
 114 #if defined(CONFIG_SYSVIPC) || defined(CONFIG_KERNELD)
 115 extern void ipc_init(void);
 116 #endif
 117 
 118 /*
 119  * Boot command-line arguments
 120  */
 121 #define MAX_INIT_ARGS 8
 122 #define MAX_INIT_ENVS 8
 123 
 124 extern void time_init(void);
 125 
 126 static unsigned long memory_start = 0;
 127 static unsigned long memory_end = 0;
 128 
 129 int rows, cols;
 130 
 131 #ifdef CONFIG_BLK_DEV_RAM
 132 extern int rd_doload;           /* 1 = load ramdisk, 0 = don't load */
 133 extern int rd_prompt;           /* 1 = prompt for ramdisk, 0 = don't prompt */
 134 extern int rd_image_start;      /* starting block # of image */
 135 #endif
 136 
 137 int root_mountflags = MS_RDONLY;
 138 char *execute_command = 0;
 139 
 140 #ifdef CONFIG_ROOT_NFS
 141 char nfs_root_name[256] = { NFS_ROOT };
 142 char nfs_root_addrs[128] = { "" };
 143 #endif
 144 
 145 extern void dquot_init(void);
 146 
 147 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 148 static char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 149 
 150 static char * argv_rc[] = { "/bin/sh", NULL };
 151 static char * envp_rc[] = { "HOME=/", "TERM=linux", NULL };
 152 
 153 static char * argv[] = { "-/bin/sh",NULL };
 154 static char * envp[] = { "HOME=/usr/root", "TERM=linux", NULL };
 155 
 156 char *get_options(char *str, int *ints)
     /*  */
 157 {
 158         char *cur = str;
 159         int i=1;
 160 
 161         while (cur && isdigit(*cur) && i <= 10) {
 162                 ints[i++] = simple_strtoul(cur,NULL,0);
 163                 if ((cur = strchr(cur,',')) != NULL)
 164                         cur++;
 165         }
 166         ints[0] = i-1;
 167         return(cur);
 168 }
 169 
 170 static void profile_setup(char *str, int *ints)
     /*  */
 171 {
 172         if (ints[0] > 0)
 173                 prof_shift = (unsigned long) ints[1];
 174         else
 175 #ifdef CONFIG_PROFILE_SHIFT
 176                 prof_shift = CONFIG_PROFILE_SHIFT;
 177 #else
 178                 prof_shift = 2;
 179 #endif
 180 }
 181 
 182 struct {
 183         const char *str;
 184         void (*setup_func)(char *, int *);
 185 } bootsetups[] = {
 186         { "reserve=", reserve_setup },
 187         { "profile=", profile_setup },
 188 #ifdef CONFIG_BLK_DEV_RAM
 189         { "ramdisk_start=", ramdisk_start_setup },
 190         { "load_ramdisk=", load_ramdisk },
 191         { "prompt_ramdisk=", prompt_ramdisk },
 192 #endif
 193         { "swap=", swap_setup },
 194         { "buff=", buff_setup },
 195 #ifdef CONFIG_BUGi386
 196         { "no-hlt", no_halt },
 197         { "no387", no_387 },
 198 #endif
 199 #ifdef CONFIG_INET
 200         { "ether=", eth_setup },
 201 #endif
 202 #ifdef CONFIG_SCSI
 203         { "max_scsi_luns=", scsi_luns_setup },
 204 #endif
 205 #ifdef CONFIG_SCSI_ADVANSYS
 206         { "advansys=", advansys_setup },
 207 #endif
 208 #if defined(CONFIG_BLK_DEV_HD)
 209         { "hd=", hd_setup },
 210 #endif
 211 #ifdef CONFIG_CHR_DEV_ST
 212         { "st=", st_setup },
 213 #endif
 214 #ifdef CONFIG_BUSMOUSE
 215         { "bmouse=", bmouse_setup },
 216 #endif
 217 #ifdef CONFIG_SCSI_SEAGATE
 218         { "st0x=", st0x_setup },
 219         { "tmc8xx=", tmc8xx_setup },
 220 #endif
 221 #ifdef CONFIG_SCSI_T128
 222         { "t128=", t128_setup },
 223 #endif
 224 #ifdef CONFIG_SCSI_PAS16
 225         { "pas16=", pas16_setup },
 226 #endif
 227 #ifdef CONFIG_SCSI_GENERIC_NCR5380
 228         { "ncr5380=", generic_NCR5380_setup },
 229 #endif
 230 #ifdef CONFIG_SCSI_AHA152X
 231         { "aha152x=", aha152x_setup},
 232 #endif
 233 #ifdef CONFIG_SCSI_AHA1542
 234         { "aha1542=", aha1542_setup},
 235 #endif
 236 #ifdef CONFIG_SCSI_AIC7XXX
 237         { "aic7xxx=", aic7xxx_setup},
 238 #endif
 239 #ifdef CONFIG_SCSI_BUSLOGIC
 240         { "BusLogic=", BusLogic_Setup},
 241 #endif
 242 #ifdef CONFIG_SCSI_NCR53C406A
 243         { "ncr53c406a=", NCR53c406a_setup},
 244 #endif
 245 #ifdef CONFIG_SCSI_FUTURE_DOMAIN
 246         { "fdomain=", fdomain_setup},
 247 #endif
 248 #ifdef CONFIG_BLK_DEV_XD
 249         { "xd=", xd_setup },
 250 #endif
 251 #ifdef CONFIG_BLK_DEV_FD
 252         { "floppy=", floppy_setup },
 253 #endif
 254 #ifdef CONFIG_CDU31A
 255         { "cdu31a=", cdu31a_setup },
 256 #endif CONFIG_CDU31A
 257 #ifdef CONFIG_MCD
 258         { "mcd=", mcd_setup },
 259 #endif CONFIG_MCD
 260 #ifdef CONFIG_MCDX
 261         { "mcdx=", mcdx_setup },
 262 #endif CONFIG_MCDX
 263 #ifdef CONFIG_SBPCD
 264         { "sbpcd=", sbpcd_setup },
 265 #endif CONFIG_SBPCD
 266 #ifdef CONFIG_AZTCD
 267         { "aztcd=", aztcd_setup },
 268 #endif CONFIG_AZTCD
 269 #ifdef CONFIG_CDU535
 270         { "sonycd535=", sonycd535_setup },
 271 #endif CONFIG_CDU535
 272 #ifdef CONFIG_GSCD
 273         { "gscd=", gscd_setup },
 274 #endif CONFIG_GSCD
 275 #ifdef CONFIG_CM206
 276         { "cm206=", cm206_setup },
 277 #endif CONFIG_CM206
 278 #ifdef CONFIG_OPTCD
 279         { "optcd=", optcd_setup },
 280 #endif CONFIG_OPTCD
 281 #ifdef CONFIG_SJCD
 282         { "sjcd=", sjcd_setup },
 283 #endif CONFIG_SJCD
 284 #ifdef CONFIG_SOUND
 285         { "sound=", sound_setup },
 286 #endif
 287         { 0, 0 }
 288 };
 289 
 290 #ifdef CONFIG_BLK_DEV_RAM
 291 static void ramdisk_start_setup(char *str, int *ints)
     /*  */
 292 {
 293    if (ints[0] > 0 && ints[1] >= 0)
 294       rd_image_start = ints[1];
 295 }
 296 
 297 static void load_ramdisk(char *str, int *ints)
     /*  */
 298 {
 299    if (ints[0] > 0 && ints[1] >= 0)
 300       rd_doload = ints[1] & 1;
 301 }
 302 
 303 static void prompt_ramdisk(char *str, int *ints)
     /*  */
 304 {
 305    if (ints[0] > 0 && ints[1] >= 0)
 306       rd_prompt = ints[1] & 1;
 307 }
 308 #endif
 309 
 310 static int checksetup(char *line)
     /*  */
 311 {
 312         int i = 0;
 313         int ints[11];
 314 
 315 #ifdef CONFIG_BLK_DEV_IDE
 316         /* ide driver needs the basic string, rather than pre-processed values */
 317         if (!strncmp(line,"ide",3) || (!strncmp(line,"hd",2) && line[2] != '=')) {
 318                 ide_setup(line);
 319                 return 1;
 320         }
 321 #endif
 322         while (bootsetups[i].str) {
 323                 int n = strlen(bootsetups[i].str);
 324                 if (!strncmp(line,bootsetups[i].str,n)) {
 325                         bootsetups[i].setup_func(get_options(line+n,ints), ints);
 326                         return 1;
 327                 }
 328                 i++;
 329         }
 330         return 0;
 331 }
 332 
 333 /* this should be approx 2 Bo*oMips to start (note initial shift), and will
 334    still work even if initally too large, it will just take slightly longer */
 335 unsigned long loops_per_sec = (1<<12);
 336 
 337 /* This is the number of bits of precision for the loops_per_second.  Each
 338    bit takes on average 1.5/HZ seconds.  This (like the original) is a little
 339    better than 1% */
 340 #define LPS_PREC 8
 341 
 342 void calibrate_delay(void)
     /*  */
 343 {
 344         int ticks;
 345         int loopbit;
 346         int lps_precision = LPS_PREC;
 347 
 348         loops_per_sec = (1<<12);
 349 
 350         printk("Calibrating delay loop.. ");
 351         while (loops_per_sec <<= 1) {
 352                 /* wait for "start of" clock tick */
 353                 ticks = jiffies;
 354                 while (ticks == jiffies)
 355                         /* nothing */;
 356                 /* Go .. */
 357                 ticks = jiffies;
 358                 __delay(loops_per_sec);
 359                 ticks = jiffies - ticks;
 360                 if (ticks)
 361                         break;
 362                 }
 363 
 364 /* Do a binary approximation to get loops_per_second set to equal one clock
 365    (up to lps_precision bits) */
 366         loops_per_sec >>= 1;
 367         loopbit = loops_per_sec;
 368         while ( lps_precision-- && (loopbit >>= 1) ) {
 369                 loops_per_sec |= loopbit;
 370                 ticks = jiffies;
 371                 while (ticks == jiffies);
 372                 ticks = jiffies;
 373                 __delay(loops_per_sec);
 374                 if (jiffies != ticks)   /* longer than 1 tick */
 375                         loops_per_sec &= ~loopbit;
 376         }
 377 
 378 /* finally, adjust loops per second in terms of seconds instead of clocks */    
 379         loops_per_sec *= HZ;
 380 /* Round the value and print it */      
 381         printk("ok - %lu.%02lu BogoMIPS\n",
 382                 (loops_per_sec+2500)/500000,
 383                 ((loops_per_sec+2500)/5000) % 100);
 384 }
 385 
 386 /*
 387  * This is a simple kernel command line parsing function: it parses
 388  * the command line, and fills in the arguments/environment to init
 389  * as appropriate. Any cmd-line option is taken to be an environment
 390  * variable if it contains the character '='.
 391  *
 392  *
 393  * This routine also checks for options meant for the kernel.
 394  * These options are not given to init - they are for internal kernel use only.
 395  */
 396 static void parse_options(char *line)
     /*  */
 397 {
 398         char *next;
 399         char *devnames[] = { "nfs", "hda", "hdb", "hdc", "hdd", "sda", "sdb",
 400                 "sdc", "sdd", "sde", "fd", "xda", "xdb", NULL };
 401         int devnums[]    = { 0x0FF, 0x300, 0x340, 0x1600, 0x1640, 0x800,
 402                 0x810, 0x820, 0x830, 0x840, 0x200, 0xD00, 0xD40, 0};
 403         int args, envs;
 404         if (!*line)
 405                 return;
 406         args = 0;
 407         envs = 1;       /* TERM is set to 'linux' by default */
 408         next = line;
 409         while ((line = next) != NULL) {
 410                 if ((next = strchr(line,' ')) != NULL)
 411                         *next++ = 0;
 412                 /*
 413                  * check for kernel options first..
 414                  */
 415                 if (!strncmp(line,"root=",5)) {
 416                         int n;
 417                         line += 5;
 418                         if (strncmp(line,"/dev/",5)) {
 419                                 ROOT_DEV = to_kdev_t(
 420                                              simple_strtoul(line,NULL,16));
 421                                 continue;
 422                         }
 423                         line += 5;
 424                         for (n = 0 ; devnames[n] ; n++) {
 425                                 int len = strlen(devnames[n]);
 426                                 if (!strncmp(line,devnames[n],len)) {
 427                                         ROOT_DEV = to_kdev_t(devnums[n]+
 428                                              simple_strtoul(line+len,NULL,0));
 429                                         break;
 430                                 }
 431                         }
 432                         continue;
 433                 }
 434 #ifdef CONFIG_ROOT_NFS
 435                 if (!strncmp(line, "nfsroot=", 8)) {
 436                         int n;
 437                         line += 8;
 438                         ROOT_DEV = MKDEV(UNNAMED_MAJOR, 255);
 439                         if (line[0] == '/' || (line[0] >= '0' && line[0] <= '9')) {
 440                                 strncpy(nfs_root_name, line, sizeof(nfs_root_name));
 441                                 nfs_root_name[sizeof(nfs_root_name)-1] = '\0';
 442                                 continue;
 443                         }
 444                         n = strlen(line) + strlen(NFS_ROOT);
 445                         if (n >= sizeof(nfs_root_name))
 446                                 line[sizeof(nfs_root_name) - strlen(NFS_ROOT) - 1] = '\0';
 447                         sprintf(nfs_root_name, NFS_ROOT, line);
 448                         continue;
 449                 }
 450                 if (!strncmp(line, "nfsaddrs=", 9)) {
 451                         line += 9;
 452                         strncpy(nfs_root_addrs, line, sizeof(nfs_root_addrs));
 453                         nfs_root_addrs[sizeof(nfs_root_addrs)] = '\0';
 454                         continue;
 455                 }
 456 #endif
 457                 if (!strcmp(line,"ro")) {
 458                         root_mountflags |= MS_RDONLY;
 459                         continue;
 460                 }
 461                 if (!strcmp(line,"rw")) {
 462                         root_mountflags &= ~MS_RDONLY;
 463                         continue;
 464                 }
 465                 if (!strcmp(line,"debug")) {
 466                         console_loglevel = 10;
 467                         continue;
 468                 }
 469                 if (!strncmp(line,"init=",5)) {
 470                         line += 5;
 471                         execute_command = line;
 472                         continue;
 473                 }
 474                 if (checksetup(line))
 475                         continue;
 476                 /*
 477                  * Then check if it's an environment variable or
 478                  * an option.
 479                  */
 480                 if (strchr(line,'=')) {
 481                         if (envs >= MAX_INIT_ENVS)
 482                                 break;
 483                         envp_init[++envs] = line;
 484                 } else {
 485                         if (args >= MAX_INIT_ARGS)
 486                                 break;
 487                         argv_init[++args] = line;
 488                 }
 489         }
 490         argv_init[args+1] = NULL;
 491         envp_init[envs+1] = NULL;
 492 }
 493 
 494 
 495 extern void setup_arch(char **, unsigned long *, unsigned long *);
 496 extern void arch_syms_export(void);
 497 
 498 #ifndef __SMP__
 499 
 500 /*
 501  *      Uniprocessor idle thread
 502  */
 503  
 504 int cpu_idle(void *unused)
     /*  */
 505 {
 506         for(;;)
 507                 idle();
 508 }
 509 
 510 #else
 511 
 512 /*
 513  *      Multiprocessor idle thread is in arch/...
 514  */
 515  
 516 extern int cpu_idle(void * unused);
 517 
 518 /*
 519  *      Activate a secondary processor.
 520  */
 521  
 522 asmlinkage void start_secondary(void)
     /*  */
 523 {
 524         trap_init();
 525         init_IRQ();
 526         smp_callin();
 527         cpu_idle(NULL);
 528 }
 529 
 530 
 531 
 532 /*
 533  *      Called by CPU#0 to activate the rest.
 534  */
 535  
 536 static void smp_init(void)
     /*  */
 537 {
 538         int i=0;
 539         smp_boot_cpus();
 540         
 541         /*
 542          *      Create the slave init tasks as sharing pid 0.
 543          */
 544 
 545         for(i=1;i<smp_num_cpus;i++)
 546         {
 547                 /*
 548                  *      We use kernel_thread for the idlers which are
 549                  *      unlocked tasks running in kernel space.
 550                  */
 551                 kernel_thread(cpu_idle, NULL, CLONE_PID);
 552                 /*
 553                  *      Assume linear processor numbering
 554                  */
 555                 current_set[i]=task[i];
 556                 current_set[i]->processor=i;
 557         }
 558 }               
 559 
 560 /*
 561  *      The autoprobe routines assume CPU#0 on the i386
 562  *      so we don't actually set the game in motion until
 563  *      they are finished.
 564  */
 565  
 566 static void smp_begin(void)
     /*  */
 567 {
 568         smp_threads_ready=1;
 569         smp_commence();
 570 }
 571         
 572 #endif
 573 
 574 /*
 575  *      Activate the first processor.
 576  */
 577  
 578 asmlinkage void start_kernel(void)
     /*  */
 579 {
 580         char * command_line;
 581 
 582 /*
 583  *      This little check will move.
 584  */
 585 
 586 #ifdef __SMP__
 587         static int first_cpu=1;
 588         
 589         if(!first_cpu)
 590                 start_secondary();
 591         first_cpu=0;
 592         
 593 #endif  
 594 /*
 595  * Interrupts are still disabled. Do necessary setups, then
 596  * enable them
 597  */
 598         setup_arch(&command_line, &memory_start, &memory_end);
 599         memory_start = paging_init(memory_start,memory_end);
 600         trap_init();
 601         init_IRQ();
 602         sched_init();
 603         time_init();
 604         parse_options(command_line);
 605 #ifdef CONFIG_MODULES
 606         init_modules();
 607 #endif
 608 #ifdef CONFIG_PROFILE
 609         if (!prof_shift)
 610 #ifdef CONFIG_PROFILE_SHIFT
 611                 prof_shift = CONFIG_PROFILE_SHIFT;
 612 #else
 613                 prof_shift = 2;
 614 #endif
 615 #endif
 616         if (prof_shift) {
 617                 prof_buffer = (unsigned long *) memory_start;
 618                 /* only text is profiled */
 619                 prof_len = (unsigned long) &_etext - (unsigned long) &_stext;
 620                 prof_len >>= prof_shift;
 621                 memory_start += prof_len * sizeof(unsigned long);
 622         }
 623         memory_start = console_init(memory_start,memory_end);
 624 #ifdef CONFIG_PCI
 625         memory_start = pci_init(memory_start,memory_end);
 626 #endif
 627         memory_start = kmalloc_init(memory_start,memory_end);
 628         sti();
 629         calibrate_delay();
 630         memory_start = inode_init(memory_start,memory_end);
 631         memory_start = file_table_init(memory_start,memory_end);
 632         memory_start = name_cache_init(memory_start,memory_end);
 633         mem_init(memory_start,memory_end);
 634         buffer_init();
 635         sock_init();
 636 #if defined(CONFIG_SYSVIPC) || defined(CONFIG_KERNELD)
 637         ipc_init();
 638 #endif
 639 #ifdef CONFIG_APM
 640         apm_bios_init();
 641 #endif
 642         dquot_init();
 643         arch_syms_export();
 644         sti();
 645         check_bugs();
 646 
 647         printk(linux_banner);
 648 #ifdef __SMP__
 649         smp_init();
 650 #endif
 651         sysctl_init();
 652         /* 
 653          *      We count on the initial thread going ok 
 654          *      Like idlers init is an unlocked kernel thread, which will
 655          *      make syscalls (and thus be locked).
 656          */
 657         kernel_thread(init, NULL, 0);
 658 /*
 659  * task[0] is meant to be used as an "idle" task: it may not sleep, but
 660  * it might do some general things like count free pages or it could be
 661  * used to implement a reasonable LRU algorithm for the paging routines:
 662  * anything that can be useful, but shouldn't take time from the real
 663  * processes.
 664  *
 665  * Right now task[0] just does a infinite idle loop.
 666  */
 667         cpu_idle(NULL);
 668 }
 669 
 670 static int printf(const char *fmt, ...)
     /*  */
 671 {
 672         va_list args;
 673         int i;
 674 
 675         va_start(args, fmt);
 676         write(1,printbuf,i=vsprintf(printbuf, fmt, args));
 677         va_end(args);
 678         return i;
 679 }
 680 
 681 static int do_rc(void * rc)
     /*  */
 682 {
 683         close(0);
 684         if (open(rc,O_RDONLY,0))
 685                 return -1;
 686         return execve("/bin/sh", argv_rc, envp_rc);
 687 }
 688 
 689 static int do_shell(void * shell)
     /*  */
 690 {
 691         close(0);close(1);close(2);
 692         setsid();
 693         (void) open("/dev/tty1",O_RDWR,0);
 694         (void) dup(0);
 695         (void) dup(0);
 696         return execve(shell, argv, envp);
 697 }
 698 
 699 static int init(void * unused)
     /*  */
 700 {
 701         int pid,i;
 702 
 703         /* Launch bdflush from here, instead of the old syscall way. */
 704         kernel_thread(bdflush, NULL, 0);
 705         /* Start the background pageout daemon. */
 706         kernel_thread(kswapd, NULL, 0);
 707 
 708         setup();
 709 
 710 #ifdef __SMP__
 711         /*
 712          *      With the devices probed and setup we can
 713          *      now enter SMP mode.
 714          */
 715         
 716         smp_begin();
 717 #endif  
 718 
 719         #ifdef CONFIG_UMSDOS_FS
 720         {
 721                 /*
 722                         When mounting a umsdos fs as root, we detect
 723                         the pseudo_root (/linux) and initialise it here.
 724                         pseudo_root is defined in fs/umsdos/inode.c
 725                 */
 726                 extern struct inode *pseudo_root;
 727                 if (pseudo_root != NULL){
 728                         current->fs->root = pseudo_root;
 729                         current->fs->pwd  = pseudo_root;
 730                 }
 731         }
 732         #endif
 733 
 734         (void) open("/dev/tty1",O_RDWR,0);
 735         (void) dup(0);
 736         (void) dup(0);
 737 
 738         if (!execute_command) {
 739                 execve("/etc/init",argv_init,envp_init);
 740                 execve("/bin/init",argv_init,envp_init);
 741                 execve("/sbin/init",argv_init,envp_init);
 742                 /* if this fails, fall through to original stuff */
 743 
 744                 pid = kernel_thread(do_rc, "/etc/rc", SIGCHLD);
 745                 if (pid>0)
 746                         while (pid != wait(&i))
 747                                 /* nothing */;
 748                 }
 749 
 750         while (1) {
 751                 pid = kernel_thread(do_shell,
 752                         execute_command ? execute_command : "/bin/sh",
 753                         SIGCHLD);
 754                 if (pid < 0) {
 755                         printf("Fork failed in init\n\r");
 756                         continue;
 757                 }
 758                 while (1)
 759                         if (pid == wait(&i))
 760                                 break;
 761                 printf("\n\rchild %d died with code %04x\n\r",pid,i);
 762                 sync();
 763         }
 764         return -1;
 765 }
/* */
root/init/main.c

DEFINITIONS
