init/main.c

/* */
This source file includes following definitions.
_syscall0
time_init
parse_options
start_kernel
printf
init
   1 /*
   2  *  linux/init/main.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 #include <stdarg.h>
   8 
   9 #include <asm/system.h>
  10 #include <asm/io.h>
  11 
  12 #include <linux/mktime.h>
  13 #include <linux/types.h>
  14 #include <linux/fcntl.h>
  15 #include <linux/config.h>
  16 #include <linux/sched.h>
  17 #include <linux/tty.h>
  18 #include <linux/head.h>
  19 #include <linux/unistd.h>
  20 #include <linux/string.h>
  21 
  22 extern unsigned long * prof_buffer;
  23 extern unsigned long prof_len;
  24 extern int end;
  25 extern char *linux_banner;
  26 
  27 /*
  28  * we need this inline - forking from kernel space will result
  29  * in NO COPY ON WRITE (!!!), until an execve is executed. This
  30  * is no problem, but for the stack. This is handled by not letting
  31  * main() use the stack at all after fork(). Thus, no function
  32  * calls - which means inline code for fork too, as otherwise we
  33  * would use the stack upon exit from 'fork()'.
  34  *
  35  * Actually only pause and fork are needed inline, so that there
  36  * won't be any messing with the stack from main(), but we define
  37  * some others too.
  38  */
  39 static inline _syscall0(int,idle)
     /*  */
  40 static inline _syscall0(int,fork)
  41 static inline _syscall0(int,pause)
  42 static inline _syscall1(int,setup,void *,BIOS)
  43 static inline _syscall0(int,sync)
  44 static inline _syscall0(pid_t,setsid)
  45 static inline _syscall3(int,write,int,fd,const char *,buf,off_t,count)
  46 static inline _syscall1(int,dup,int,fd)
  47 static inline _syscall3(int,execve,const char *,file,char **,argv,char **,envp)
  48 static inline _syscall3(int,open,const char *,file,int,flag,int,mode)
  49 static inline _syscall1(int,close,int,fd)
  50 static inline _syscall3(pid_t,waitpid,pid_t,pid,int *,wait_stat,int,options)
  51 
  52 static inline pid_t wait(int * wait_stat)
  53 {
  54         return waitpid(-1,wait_stat,0);
  55 }
  56 
  57 static char printbuf[1024];
  58 
  59 extern int vsprintf();
  60 extern void init(void);
  61 extern void init_IRQ(void);
  62 extern long blk_dev_init(long,long);
  63 extern long chr_dev_init(long,long);
  64 extern void floppy_init(void);
  65 extern void sock_init(void);
  66 extern long rd_init(long mem_start, int length);
  67 extern long kernel_mktime(struct mktime * time);
  68 extern unsigned long simple_strtoul(const char *cp,char **endp,unsigned int
  69     base);
  70 
  71 #ifdef CONFIG_SCSI
  72 extern unsigned long scsi_dev_init(unsigned long, unsigned long);
  73 #endif
  74 
  75 /*
  76  * This is set up by the setup-routine at boot-time
  77  */
  78 #define EXT_MEM_K (*(unsigned short *)0x90002)
  79 #define DRIVE_INFO (*(struct drive_info *)0x90080)
  80 #define SCREEN_INFO (*(struct screen_info *)0x90000)
  81 #define RAMDISK_SIZE (*(unsigned short *)0x901F8)
  82 #define ORIG_ROOT_DEV (*(unsigned short *)0x901FC)
  83 #define AUX_DEVICE_INFO (*(unsigned char *)0x901FF)
  84 
  85 /*
  86  * Boot command-line arguments
  87  */
  88 #define MAX_INIT_ARGS 8
  89 #define MAX_INIT_ENVS 8
  90 #define CL_MAGIC_ADDR (*(unsigned short *) 0x90020)
  91 #define CL_MAGIC 0xa33f
  92 #define CL_BASE_ADDR ((char *) 0x90000)
  93 #define CL_OFFSET (*(unsigned short *) 0x90022)
  94 
  95 /*
  96  * Yeah, yeah, it's ugly, but I cannot find how to do this correctly
  97  * and this seems to work. I anybody has more info on the real-time
  98  * clock I'd be interested. Most of this was trial and error, and some
  99  * bios-listing reading. Urghh.
 100  */
 101 
 102 #define CMOS_READ(addr) ({ \
 103 outb_p(addr,0x70); \
 104 inb_p(0x71); \
 105 })
 106 
 107 #define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10)
 108 
 109 static void time_init(void)
     /*  */
 110 {
 111         struct mktime time;
 112         int i;
 113 
 114         for (i = 0 ; i < 1000000 ; i++)
 115                 if (!(CMOS_READ(10) & 0x80))
 116                         break;
 117         do {
 118                 time.sec = CMOS_READ(0);
 119                 time.min = CMOS_READ(2);
 120                 time.hour = CMOS_READ(4);
 121                 time.day = CMOS_READ(7);
 122                 time.mon = CMOS_READ(8);
 123                 time.year = CMOS_READ(9);
 124         } while (time.sec != CMOS_READ(0));
 125         BCD_TO_BIN(time.sec);
 126         BCD_TO_BIN(time.min);
 127         BCD_TO_BIN(time.hour);
 128         BCD_TO_BIN(time.day);
 129         BCD_TO_BIN(time.mon);
 130         BCD_TO_BIN(time.year);
 131         time.mon--;
 132         startup_time = kernel_mktime(&time);
 133 }
 134 
 135 static unsigned long memory_start = 0; /* After mem_init, stores the */
 136                                        /* amount of free user memory */
 137 static unsigned long memory_end = 0;
 138 static unsigned long low_memory_start = 0;
 139 
 140 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 141 static char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=console", NULL, };
 142 
 143 static char * argv_rc[] = { "/bin/sh", NULL };
 144 static char * envp_rc[] = { "HOME=/", "TERM=console", NULL };
 145 
 146 static char * argv[] = { "-/bin/sh",NULL };
 147 static char * envp[] = { "HOME=/usr/root", "TERM=console", NULL };
 148 
 149 struct drive_info { char dummy[32]; } drive_info;
 150 struct screen_info screen_info;
 151 
 152 unsigned char aux_device_present;
 153 int ramdisk_size;
 154 
 155 static char command_line[80] = { 0, };
 156 
 157 /*
 158  * This is a simple kernel command line parsing function: it parses
 159  * the command line, and fills in the arguments/environment to init
 160  * as appropriate. Any cmd-line option is taken to be an environment
 161  * variable if it contains the character '='.
 162  *
 163  *
 164  * This routine also checks for options meant for the kernel - currently
 165  * only the "root=XXXX" option is recognized. These options are not given
 166  * to init - they are for internal kernel use only.
 167  */
 168 static void parse_options(char *line)
     /*  */
 169 {
 170         char *next;
 171         int args, envs;
 172 
 173         if (!*line)
 174                 return;
 175         args = 0;
 176         envs = 1;       /* TERM is set to 'console' by default */
 177         next = line;
 178         while ((line = next) != NULL) {
 179                 if ((next = strchr(line,' ')) != NULL)
 180                         *next++ = 0;
 181                 /*
 182                  * check for kernel options first..
 183                  */
 184                 if (!strncmp(line,"root=",5)) {
 185                         ROOT_DEV = simple_strtoul(line+5,NULL,16);
 186                         continue;
 187                 }
 188                 /*
 189                  * Then check if it's an environment variable or
 190                  * an option.
 191                  */     
 192                 if (strchr(line,'=')) {
 193                         if (envs >= MAX_INIT_ENVS)
 194                                 break;
 195                         envp_init[++envs] = line;
 196                 } else {
 197                         if (args >= MAX_INIT_ARGS)
 198                                 break;
 199                         argv_init[++args] = line;
 200                 }
 201         }
 202         argv_init[args+1] = NULL;
 203         envp_init[envs+1] = NULL;
 204 }
 205 
 206 void start_kernel(void)
     /*  */
 207 {
 208 /*
 209  * Interrupts are still disabled. Do necessary setups, then
 210  * enable them
 211  */
 212         ROOT_DEV = ORIG_ROOT_DEV;
 213         drive_info = DRIVE_INFO;
 214         screen_info = SCREEN_INFO;
 215         aux_device_present = AUX_DEVICE_INFO;
 216         memory_end = (1<<20) + (EXT_MEM_K<<10);
 217         memory_end &= 0xfffff000;
 218         ramdisk_size = RAMDISK_SIZE;
 219 #ifdef CONFIG_MAX_16M
 220         if (memory_end > 16*1024*1024)
 221                 memory_end = 16*1024*1024;
 222 #endif
 223         if ((unsigned long)&end >= (1024*1024)) {
 224                 memory_start = (unsigned long) &end;
 225                 low_memory_start = 4096;
 226         } else {
 227                 memory_start = 1024*1024;
 228                 low_memory_start = (unsigned long) &end;
 229         }
 230         low_memory_start += 0xfff;
 231         low_memory_start &= 0xfffff000;
 232         memory_start = paging_init(memory_start,memory_end);
 233         if (CL_MAGIC_ADDR == CL_MAGIC)
 234                 strcpy(command_line,CL_BASE_ADDR+CL_OFFSET);
 235         trap_init();
 236         init_IRQ();
 237         sched_init();
 238         parse_options(command_line);
 239 #ifdef CONFIG_PROFILE
 240         prof_buffer = (unsigned long *) memory_start;
 241         prof_len = (unsigned long) &end;
 242         prof_len >>= 2;
 243         memory_start += prof_len * sizeof(unsigned long);
 244 #endif
 245         memory_start = chr_dev_init(memory_start,memory_end);
 246         memory_start = blk_dev_init(memory_start,memory_end);
 247 #ifdef CONFIG_SCSI
 248         memory_start = scsi_dev_init(memory_start,memory_end);
 249 #endif
 250         memory_start = inode_init(memory_start,memory_end);
 251         mem_init(low_memory_start,memory_start,memory_end);
 252         buffer_init();
 253         time_init();
 254         floppy_init();
 255         sock_init();
 256         sti();
 257         /*
 258          * check if exception 16 works correctly.. This is truly evil
 259          * code: it disables the high 8 interrupts to make sure that
 260          * the irq13 doesn't happen. But as this will lead to a lockup
 261          * if no exception16 arrives, it depends on the fact that the
 262          * high 8 interrupts will be re-enabled by the next timer tick.
 263          * So the irq13 will happen eventually, but the exception 16
 264          * should get there first..
 265          */
 266         if (hard_math) {
 267                 unsigned short control_word;
 268 
 269                 printk("Checking for 387 error mechanism ...");
 270                 __asm__("fninit ; fnstcw %0 ; fwait":"=m" (*&control_word));
 271                 control_word &= 0xffc0;
 272                 __asm__("fldcw %0 ; fwait"::"m" (*&control_word));
 273                 outb_p(inb_p(0x21) | (1 << 2), 0x21);
 274                 __asm__("fldz ; fld1 ; fdiv %st,%st(1) ; fwait");
 275                 printk(" ok, using %s.\n",ignore_irq13?"exception 16":"irq13");
 276         }
 277         move_to_user_mode();
 278         if (!fork())            /* we count on this going ok */
 279                 init();
 280 /*
 281  * task[0] is meant to be used as an "idle" task: it may not sleep, but
 282  * it might do some general things like count free pages or it could be
 283  * used to implement a reasonable LRU algorithm for the paging routines:
 284  * anything that can be useful, but shouldn't take time from the real
 285  * processes.
 286  *
 287  * Right now task[0] just does a infinite idle loop.
 288  */
 289         for(;;)
 290                 idle();
 291 }
 292 
 293 static int printf(const char *fmt, ...)
     /*  */
 294 {
 295         va_list args;
 296         int i;
 297 
 298         va_start(args, fmt);
 299         write(1,printbuf,i=vsprintf(printbuf, fmt, args));
 300         va_end(args);
 301         return i;
 302 }
 303 
 304 void init(void)
     /*  */
 305 {
 306         int pid,i;
 307 
 308         setup((void *) &drive_info);
 309         (void) open("/dev/tty1",O_RDWR,0);
 310         (void) dup(0);
 311         (void) dup(0);
 312 
 313         printf(linux_banner);
 314         execve("/etc/init",argv_init,envp_init);
 315         execve("/bin/init",argv_init,envp_init);
 316         execve("/sbin/init",argv_init,envp_init);
 317         /* if this fails, fall through to original stuff */
 318 
 319         if (!(pid=fork())) {
 320                 close(0);
 321                 if (open("/etc/rc",O_RDONLY,0))
 322                         _exit(1);
 323                 execve("/bin/sh",argv_rc,envp_rc);
 324                 _exit(2);
 325         }
 326         if (pid>0)
 327                 while (pid != wait(&i))
 328                         /* nothing */;
 329         while (1) {
 330                 if ((pid = fork()) < 0) {
 331                         printf("Fork failed in init\r\n");
 332                         continue;
 333                 }
 334                 if (!pid) {
 335                         close(0);close(1);close(2);
 336                         setsid();
 337                         (void) open("/dev/tty1",O_RDWR,0);
 338                         (void) dup(0);
 339                         (void) dup(0);
 340                         _exit(execve("/bin/sh",argv,envp));
 341                 }
 342                 while (1)
 343                         if (pid == wait(&i))
 344                                 break;
 345                 printf("\n\rchild %d died with code %04x\n\r",pid,i);
 346                 sync();
 347         }
 348         _exit(0);       /* NOTE! _exit, not exit() */
 349 }
/* */
root/init/main.c

DEFINITIONS
