#define __LIBRARY__#include #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 _syscall0(int,setup)static inline _syscall0(int,sync)#include #include #include #include system.h>#include #include #include #include #include #include #include static char printbuf[1024];extern int vsprintf();extern void init(void);extern void hd_init(void);extern long kernel_mktime(struct tm * tm);extern long startup_time;/* * 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) ({ ///禁止NMI（不可屏蔽中断）outb_p(0x80|addr,0x70); /inb_p(0x71); /})#define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10)//二进制编码的十进制表示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)-1;time.tm_year = CMOS_READ(9);} while (time.tm_sec != CMOS_READ(0));//一定要在1秒之间完成time结构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);startup_time = kernel_mktime(&time);}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 */time_init();tty_init();trap_init();sched_init();buffer_init();hd_init();sti();move_to_user_mode();//转入用户模式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();//暂停task0，循环让其他进程运行，在这里其实只有一个0任务}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[] = { "-",NULL };static char * envp[] = { "HOME=/usr/root", NULL };void init(void){int i,j;setup();//读取硬盘信息，并将信息存入start_buffer->b_data中，并保存分区信息，登记根超级块if (!fork())_exit(execve("/bin/update",NULL,NULL));(void) open("/dev/tty0",O_RDWR,0);(void) dup(0);//复制一个tty0(void) dup(0);//再复制一个tty0printf("%d buffers = %d bytes buffer space/n/r",NR_BUFFERS,NR_BUFFERS*BLOCK_SIZE);printf(" Ok./n/r");if ((i=fork())<0)//复制当前进程printf("Fork failed in init/r/n");else if (!i) {//如果成功close(0);close(1);close(2);//关闭打开的3个tty0文件setsid();(void) open("/dev/tty0",O_RDWR,0);(void) dup(0);(void) dup(0);_exit(execve("/bin/sh",argv,envp));//执行shell}j=wait(&i);printf("child %d died with code %04x/n",j,i);sync();_exit(0);/* NOTE! _exit, not exit() */}
