/* *  linux/init/main.c * *  (C) 1991  Linus Torvalds */#define __LIBRARY__#include <unistd.h>#include <time.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)#include <linux/tty.h>#include <linux/sched.h>#include <linux/head.h>#include <asm/system.h>#include <asm/io.h>#include <stddef.h>#include <stdarg.h>#include <unistd.h>#include <fcntl.h>#include <sys/types.h>#include <linux/fs.h>static char printbuf[1024];extern int vsprintf();extern void init(void);extern void blk_dev_init(void);extern void chr_dev_init(void);extern void hd_init(void);extern void floppy_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);extern long startup_time;/* * This is set up by the setup-routine at boot-time */#define EXT_MEM_K (*(unsigned short *)0x90002)#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;struct drive_info { char dummy[32]; } drive_info;void main(void)		/* This really IS void, no error here. */{			/* The startup routine assumes (well, ...) this *//* * Interrupts are still disabled. Do necessary setups, then * enable them */ 	ROOT_DEV = ORIG_ROOT_DEV; 	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		buffer_memory_end = 1*1024*1024;	main_memory_start = buffer_memory_end;#ifdef RAMDISK	main_memory_start += rd_init(main_memory_start, RAMDISK*1024);#endif	mem_init(main_memory_start,memory_end);	trap_init();	blk_dev_init();	chr_dev_init();	tty_init();	time_init();	sched_init();	buffer_init(buffer_memory_end);	hd_init();	floppy_init();	sti();	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(;;) pause();}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;}static char * argv_rc[] = { "/bin/sh", NULL };static char * envp_rc[] = { "HOME=/", NULL };static char * argv[] = { "-/bin/sh",NULL };static char * envp[] = { "HOME=/usr/root", NULL };void init(void){	int pid,i;	setup((void *) &drive_info);	(void) open("/dev/tty0",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);	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/tty0",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() */}