init/main.c

/* */
This source file includes following definitions.
time_init
main
printf
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 rd_init(long mem_start, int length);
  52 extern long kernel_mktime(struct tm * tm);
  53 extern long startup_time;
  54 
  55 /*
  56  * This is set up by the setup-routine at boot-time
  57  */
  58 #define EXT_MEM_K (*(unsigned short *)0x90002)
  59 #define DRIVE_INFO (*(struct drive_info *)0x90080)
  60 #define ORIG_ROOT_DEV (*(unsigned short *)0x901FC)
  61 
  62 /*
  63  * Yeah, yeah, it's ugly, but I cannot find how to do this correctly
  64  * and this seems to work. I anybody has more info on the real-time
  65  * clock I'd be interested. Most of this was trial and error, and some
  66  * bios-listing reading. Urghh.
  67  */
  68 
  69 #define CMOS_READ(addr) ({ \
  70 outb_p(0x80|addr,0x70); \
  71 inb_p(0x71); \
  72 })
  73 
  74 #define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10)
  75 
  76 static void time_init(void)
     /*  */
  77 {
  78         struct tm time;
  79 
  80         do {
  81                 time.tm_sec = CMOS_READ(0);
  82                 time.tm_min = CMOS_READ(2);
  83                 time.tm_hour = CMOS_READ(4);
  84                 time.tm_mday = CMOS_READ(7);
  85                 time.tm_mon = CMOS_READ(8);
  86                 time.tm_year = CMOS_READ(9);
  87         } while (time.tm_sec != CMOS_READ(0));
  88         BCD_TO_BIN(time.tm_sec);
  89         BCD_TO_BIN(time.tm_min);
  90         BCD_TO_BIN(time.tm_hour);
  91         BCD_TO_BIN(time.tm_mday);
  92         BCD_TO_BIN(time.tm_mon);
  93         BCD_TO_BIN(time.tm_year);
  94         time.tm_mon--;
  95         startup_time = kernel_mktime(&time);
  96 }
  97 
  98 static long memory_end = 0;
  99 static long buffer_memory_end = 0;
 100 static long main_memory_start = 0;
 101 
 102 struct drive_info { char dummy[32]; } drive_info;
 103 
 104 void main(void)         /* This really IS void, no error here. */
     /*  */
 105 {                       /* The startup routine assumes (well, ...) this */
 106 /*
 107  * Interrupts are still disabled. Do necessary setups, then
 108  * enable them
 109  */
 110         ROOT_DEV = ORIG_ROOT_DEV;
 111         drive_info = DRIVE_INFO;
 112         memory_end = (1<<20) + (EXT_MEM_K<<10);
 113         memory_end &= 0xfffff000;
 114         if (memory_end > 16*1024*1024)
 115                 memory_end = 16*1024*1024;
 116         if (memory_end > 12*1024*1024) 
 117                 buffer_memory_end = 4*1024*1024;
 118         else if (memory_end > 6*1024*1024)
 119                 buffer_memory_end = 2*1024*1024;
 120         else
 121                 buffer_memory_end = 1*1024*1024;
 122         main_memory_start = buffer_memory_end;
 123 #ifdef RAMDISK
 124         main_memory_start += rd_init(main_memory_start, RAMDISK*1024);
 125 #endif
 126         mem_init(main_memory_start,memory_end);
 127         trap_init();
 128         blk_dev_init();
 129         chr_dev_init();
 130         tty_init();
 131         time_init();
 132         sched_init();
 133         buffer_init(buffer_memory_end);
 134         hd_init();
 135         floppy_init();
 136         sti();
 137         move_to_user_mode();
 138         if (!fork()) {          /* we count on this going ok */
 139                 init();
 140         }
 141 /*
 142  *   NOTE!!   For any other task 'pause()' would mean we have to get a
 143  * signal to awaken, but task0 is the sole exception (see 'schedule()')
 144  * as task 0 gets activated at every idle moment (when no other tasks
 145  * can run). For task0 'pause()' just means we go check if some other
 146  * task can run, and if not we return here.
 147  */
 148         for(;;) pause();
 149 }
 150 
 151 static int printf(const char *fmt, ...)
     /*  */
 152 {
 153         va_list args;
 154         int i;
 155 
 156         va_start(args, fmt);
 157         write(1,printbuf,i=vsprintf(printbuf, fmt, args));
 158         va_end(args);
 159         return i;
 160 }
 161 
 162 static char * argv_rc[] = { "/bin/sh", NULL };
 163 static char * envp_rc[] = { "HOME=/", NULL };
 164 
 165 static char * argv[] = { "-/bin/sh",NULL };
 166 static char * envp[] = { "HOME=/usr/root", NULL };
 167 
 168 void init(void)
     /*  */
 169 {
 170         int pid,i;
 171 
 172         setup((void *) &drive_info);
 173         (void) open("/dev/tty0",O_RDWR,0);
 174         (void) dup(0);
 175         (void) dup(0);
 176         printf("%d buffers = %d bytes buffer space\n\r",NR_BUFFERS,
 177                 NR_BUFFERS*BLOCK_SIZE);
 178         printf("Free mem: %d bytes\n\r",memory_end-main_memory_start);
 179         if (!(pid=fork())) {
 180                 close(0);
 181                 if (open("/etc/rc",O_RDONLY,0))
 182                         _exit(1);
 183                 execve("/bin/sh",argv_rc,envp_rc);
 184                 _exit(2);
 185         }
 186         if (pid>0)
 187                 while (pid != wait(&i))
 188                         /* nothing */;
 189         while (1) {
 190                 if ((pid=fork())<0) {
 191                         printf("Fork failed in init\r\n");
 192                         continue;
 193                 }
 194                 if (!pid) {
 195                         close(0);close(1);close(2);
 196                         setsid();
 197                         (void) open("/dev/tty0",O_RDWR,0);
 198                         (void) dup(0);
 199                         (void) dup(0);
 200                         _exit(execve("/bin/sh",argv,envp));
 201                 }
 202                 while (1)
 203                         if (pid == wait(&i))
 204                                 break;
 205                 printf("\n\rchild %d died with code %04x\n\r",pid,i);
 206                 sync();
 207         }
 208         _exit(0);       /* NOTE! _exit, not exit() */
 209 }
/* */
root/init/main.c

DEFINITIONS
