Linux0.96c/init/main.c
/*
* linux/init/main.c
*
* (C) 1991 Linus Torvalds
*/
#include <stddef.h>
#include <stdarg.h>
#include <time.h>
#include <sys/types.h>
#include <asm/system.h>
#include <asm/io.h>
#include <linux/fcntl.h>
#include <linux/config.h>
#include <linux/sched.h>
#include <linux/tty.h>
#include <linux/head.h>
#include <linux/unistd.h>
/*
* we need this inline - forking from kernel space will result
* in NO COPY ON WRITE (!!!), until an execve is executed. This
* is no problem, but for the stack. This is handled by not letting
* main() use the stack at all after fork(). Thus, no function
* calls - which means inline code for fork too, as otherwise we
* would use the stack upon exit from 'fork()'.
*
* Actually only pause and fork are needed inline, so that there
* won't be any messing with the stack from main(), but we define
* some others too.
*/
static inline _syscall0(int,fork)
static inline _syscall0(int,pause)
static inline _syscall1(int,setup,void *,BIOS)
static inline _syscall0(int,sync)
static inline _syscall0(pid_t,setsid)
static inline _syscall3(int,write,int,fd,const char *,buf,off_t,count)
static inline _syscall1(int,dup,int,fd)
static inline _syscall3(int,execve,const char *,file,char **,argv,char **,envp)
static inline _syscall3(int,open,const char *,file,int,flag,int,mode)
static inline _syscall1(int,close,int,fd)
static inline _syscall3(pid_t,waitpid,pid_t,pid,int *,wait_stat,int,options)
static inline pid_t wait(int * wait_stat)
{
return waitpid(-1,wait_stat,0);
}
static char printbuf[1024];
extern int vsprintf();
extern void init(void);
extern long blk_dev_init(long,long);
extern long chr_dev_init(long,long);
extern void hd_init(void);
extern void floppy_init(void);
extern void sock_init(void);
extern void mem_init(long start, long end);
extern long rd_init(long mem_start, int length);
extern long kernel_mktime(struct tm * tm);
#ifdef CONFIG_SCSI
extern void scsi_dev_init(void);
#endif
static int sprintf(char * str, const char *fmt, ...)
{
va_list args;
int i;
va_start(args, fmt);
i = vsprintf(str, fmt, args);
va_end(args);
return i;
}
/*
* This is set up by the setup-routine at boot-time
*/
#define EXT_MEM_K (*(unsigned short *)0x90002)
#define CON_ROWS ((*(unsigned short *)0x9000e) & 0xff)
#define CON_COLS (((*(unsigned short *)0x9000e) & 0xff00) >> 8)
#define DRIVE_INFO (*(struct drive_info *)0x90080)
#define ORIG_ROOT_DEV (*(unsigned short *)0x901FC)
/*
* Yeah, yeah, it's ugly, but I cannot find how to do this correctly
* and this seems to work. I anybody has more info on the real-time
* clock I'd be interested. Most of this was trial and error, and some
* bios-listing reading. Urghh.
*/
#define CMOS_READ(addr) ({ \
outb_p(0x80|addr,0x70); \
inb_p(0x71); \
})
#define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10)
static void time_init(void)
{
struct tm time;
do {
time.tm_sec = CMOS_READ(0);
time.tm_min = CMOS_READ(2);
time.tm_hour = CMOS_READ(4);
time.tm_mday = CMOS_READ(7);
time.tm_mon = CMOS_READ(8);
time.tm_year = CMOS_READ(9);
} while (time.tm_sec != CMOS_READ(0));
BCD_TO_BIN(time.tm_sec);
BCD_TO_BIN(time.tm_min);
BCD_TO_BIN(time.tm_hour);
BCD_TO_BIN(time.tm_mday);
BCD_TO_BIN(time.tm_mon);
BCD_TO_BIN(time.tm_year);
time.tm_mon--;
startup_time = kernel_mktime(&time);
}
static long memory_end = 0;
static long buffer_memory_end = 0;
static long main_memory_start = 0;
static char term[32];
static char * argv_init[] = { "/bin/init", NULL };
static char * envp_init[] = { "HOME=/", NULL, NULL };
static char * argv_rc[] = { "/bin/sh", NULL };
static char * envp_rc[] = { "HOME=/", NULL ,NULL };
static char * argv[] = { "-/bin/sh",NULL };
static char * envp[] = { "HOME=/usr/root", NULL, NULL };
struct drive_info { char dummy[32]; } drive_info;
void start_kernel(void)
{
/*
* Interrupts are still disabled. Do necessary setups, then
* enable them
*/
ROOT_DEV = ORIG_ROOT_DEV;
sprintf(term, "TERM=con%dx%d", CON_COLS, CON_ROWS);
envp[1] = term;
envp_rc[1] = term;
envp_init[1] = term;
drive_info = DRIVE_INFO;
memory_end = (1<<20) + (EXT_MEM_K<<10);
memory_end &= 0xfffff000;
if (memory_end > 16*1024*1024)
memory_end = 16*1024*1024;
if (memory_end >= 12*1024*1024)
buffer_memory_end = 4*1024*1024;
else if (memory_end >= 6*1024*1024)
buffer_memory_end = 2*1024*1024;
else if (memory_end >= 4*1024*1024)
buffer_memory_end = 3*512*1024;
else
buffer_memory_end = 1*1024*1024;
main_memory_start = buffer_memory_end;
trap_init();
sched_init();
main_memory_start = chr_dev_init(main_memory_start,memory_end);
main_memory_start = blk_dev_init(main_memory_start,memory_end);
mem_init(main_memory_start,memory_end);
time_init();
printk("Linux version " UTS_RELEASE " " __DATE__ " " __TIME__ "\n");
buffer_init(buffer_memory_end);
hd_init();
floppy_init();
sock_init();
sti();
#ifdef CONFIG_SCSI
scsi_dev_init();
#endif
move_to_user_mode();
if (!fork()) { /* we count on this going ok */
init();
}
/*
* NOTE!! For any other task 'pause()' would mean we have to get a
* signal to awaken, but task0 is the sole exception (see 'schedule()')
* as task 0 gets activated at every idle moment (when no other tasks
* can run). For task0 'pause()' just means we go check if some other
* task can run, and if not we return here.
*/
for(;;)
__asm__("int $0x80"::"a" (__NR_pause):"ax");
}
static int printf(const char *fmt, ...)
{
va_list args;
int i;
va_start(args, fmt);
write(1,printbuf,i=vsprintf(printbuf, fmt, args));
va_end(args);
return i;
}
void init(void)
{
int pid,i;
setup((void *) &drive_info);
(void) open("/dev/tty1",O_RDWR,0);
(void) dup(0);
(void) dup(0);
printf("%d buffers = %d bytes buffer space\n\r",NR_BUFFERS,
NR_BUFFERS*BLOCK_SIZE);
printf("Free mem: %d bytes\n\r",memory_end-main_memory_start);
execve("/etc/init",argv_init,envp_init);
execve("/bin/init",argv_init,envp_init);
/* if this fails, fall through to original stuff */
if (!(pid=fork())) {
close(0);
if (open("/etc/rc",O_RDONLY,0))
_exit(1);
execve("/bin/sh",argv_rc,envp_rc);
_exit(2);
}
if (pid>0)
while (pid != wait(&i))
/* nothing */;
while (1) {
if ((pid=fork())<0) {
printf("Fork failed in init\r\n");
continue;
}
if (!pid) {
close(0);close(1);close(2);
setsid();
(void) open("/dev/tty1",O_RDWR,0);
(void) dup(0);
(void) dup(0);
_exit(execve("/bin/sh",argv,envp));
}
while (1)
if (pid == wait(&i))
break;
printf("\n\rchild %d died with code %04x\n\r",pid,i);
sync();
}
_exit(0); /* NOTE! _exit, not exit() */
}