root/init/main.c

/* */

DEFINITIONS

1. time_init
2. main
3. printf
4. init

   1 /*
   2  *  linux/init/main.c
   3  *
   4  *  (C) 1991  Linus Torvalds
   5  */
   6 
   7 #define __LIBRARY__
   8 #include <unistd.h>
   9 #include <time.h>
  10 
  11 /*
  12  * we need this inline - forking from kernel space will result
  13  * in NO COPY ON WRITE (!!!), until an execve is executed. This
  14  * is no problem, but for the stack. This is handled by not letting
  15  * main() use the stack at all after fork(). Thus, no function
  16  * calls - which means inline code for fork too, as otherwise we
  17  * would use the stack upon exit from 'fork()'.
  18  *
  19  * Actually only pause and fork are needed inline, so that there
  20  * won't be any messing with the stack from main(), but we define
  21  * some others too.
  22  */
  23 static inline _syscall0(int,fork)
  24 static inline _syscall0(int,pause)
  25 static inline _syscall1(int,setup,void *,BIOS)
  26 static inline _syscall0(int,sync)
  27 
  28 #include <linux/tty.h>
  29 #include <linux/sched.h>
  30 #include <linux/head.h>
  31 #include <asm/system.h>
  32 #include <asm/io.h>
  33 
  34 #include <stddef.h>
  35 #include <stdarg.h>
  36 #include <unistd.h>
  37 #include <fcntl.h>
  38 #include <sys/types.h>
  39 
  40 #include <linux/fs.h>
  41 
  42 static char printbuf[1024];
  43 
  44 extern int vsprintf();
  45 extern void init(void);
  46 extern void blk_dev_init(void);
  47 extern void chr_dev_init(void);
  48 extern void hd_init(void);
  49 extern void floppy_init(void);
  50 extern void mem_init(long start, long end);
  51 extern long kernel_mktime(struct tm * tm);
  52 extern long startup_time;
  53 
  54 /*
  55  * This is set up by the setup-routine at boot-time
  56  */
  57 #define EXT_MEM_K (*(unsigned short *)0x90002)
  58 #define DRIVE_INFO (*(struct drive_info *)0x90080)
  59 #define ORIG_ROOT_DEV (*(unsigned short *)0x901FC)
  60 
  61 /*
  62  * Yeah, yeah, it's ugly, but I cannot find how to do this correctly
  63  * and this seems to work. I anybody has more info on the real-time
  64  * clock I'd be interested. Most of this was trial and error, and some
  65  * bios-listing reading. Urghh.
  66  */
  67 
  68 #define CMOS_READ(addr) ({ \
  69 outb_p(0x80|addr,0x70); \
  70 inb_p(0x71); \
  71 })
  72 
  73 #define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10)
  74 
  75 static void time_init(void)
     /*  */
  76 {
  77         struct tm time;
  78 
  79         do {
  80                 time.tm_sec = CMOS_READ(0);
  81                 time.tm_min = CMOS_READ(2);
  82                 time.tm_hour = CMOS_READ(4);
  83                 time.tm_mday = CMOS_READ(7);
  84                 time.tm_mon = CMOS_READ(8);
  85                 time.tm_year = CMOS_READ(9);
  86         } while (time.tm_sec != CMOS_READ(0));
  87         BCD_TO_BIN(time.tm_sec);
  88         BCD_TO_BIN(time.tm_min);
  89         BCD_TO_BIN(time.tm_hour);
  90         BCD_TO_BIN(time.tm_mday);
  91         BCD_TO_BIN(time.tm_mon);
  92         BCD_TO_BIN(time.tm_year);
  93         time.tm_mon--;
  94         startup_time = kernel_mktime(&time);
  95 }
  96 
  97 static long memory_end = 0;
  98 static long buffer_memory_end = 0;
  99 
 100 struct drive_info { char dummy[32]; } drive_info;
 101 
 102 void main(void)         /* This really IS void, no error here. */
     /*  */
 103 {                       /* The startup routine assumes (well, ...) this */
 104 /*
 105  * Interrupts are still disabled. Do necessary setups, then
 106  * enable them
 107  */
 108         ROOT_DEV = ORIG_ROOT_DEV;
 109         drive_info = DRIVE_INFO;
 110         memory_end = (1<<20) + (EXT_MEM_K<<10);
 111         memory_end &= 0xfffff000;
 112         if (memory_end > 16*1024*1024)
 113                 memory_end = 16*1024*1024;
 114         if (memory_end > 6*1024*1024)
 115                 buffer_memory_end = 2*1024*1024;
 116         else
 117                 buffer_memory_end = 1*1024*1024;
 118         mem_init(buffer_memory_end,memory_end);
 119         trap_init();
 120         blk_dev_init();
 121         chr_dev_init();
 122         tty_init();
 123         time_init();
 124         sched_init();
 125         buffer_init(buffer_memory_end);
 126         hd_init();
 127         floppy_init();
 128         sti();
 129         move_to_user_mode();
 130         if (!fork()) {          /* we count on this going ok */
 131                 init();
 132         }
 133 /*
 134  *   NOTE!!   For any other task 'pause()' would mean we have to get a
 135  * signal to awaken, but task0 is the sole exception (see 'schedule()')
 136  * as task 0 gets activated at every idle moment (when no other tasks
 137  * can run). For task0 'pause()' just means we go check if some other
 138  * task can run, and if not we return here.
 139  */
 140         for(;;) pause();
 141 }
 142 
 143 static int printf(const char *fmt, ...)
     /*  */
 144 {
 145         va_list args;
 146         int i;
 147 
 148         va_start(args, fmt);
 149         write(1,printbuf,i=vsprintf(printbuf, fmt, args));
 150         va_end(args);
 151         return i;
 152 }
 153 
 154 static char * argv[] = { "-/bin/sh",NULL };
 155 static char * envp[] = { "HOME=/usr/root", NULL };
 156 
 157 void init(void)
     /*  */
 158 {
 159         int i,j;
 160 
 161         setup((void *) &drive_info);
 162         if (!fork())
 163                 _exit(execve("/bin/update",NULL,NULL));
 164         (void) open("/dev/tty0",O_RDWR,0);
 165         (void) dup(0);
 166         (void) dup(0);
 167         printf("%d buffers = %d bytes buffer space\n\r",NR_BUFFERS,
 168                 NR_BUFFERS*BLOCK_SIZE);
 169         printf("Free mem: %d bytes\n\r",memory_end-buffer_memory_end);
 170         printf(" Ok.\n\r");
 171         if ((i=fork())<0)
 172                 printf("Fork failed in init\r\n");
 173         else if (!i) {
 174                 close(0);close(1);close(2);
 175                 setsid();
 176                 (void) open("/dev/tty0",O_RDWR,0);
 177                 (void) dup(0);
 178                 (void) dup(0);
 179                 _exit(execve("/bin/sh",argv,envp));
 180         }
 181         j=wait(&i);
 182         printf("child %d died with code %04x\n",j,i);
 183         sync();
 184         _exit(0);       /* NOTE! _exit, not exit() */
 185 }

/* */