code:rexit - ikarishinjieva/unixV6-code-analyze-chs GitHub Wiki

3200 /* -------------------------*/

3201

3202 /* exit system call:

3203  * pass back caller's r0

3204  */

3205 rexit()

3206 {

3207

3208     u.u_arg[0] = u.u_ar0[R0] << 8;

• 将R0左移8位放入u.u_arg[0]中,R0是从用户态传入的参数
  • 关于为什么要左移8位,参见遗留问题
• u.u_arg[0]后会在wait3297中被用到

3209     exit();

• 调用exit函数自我终止

3210 }

3211 /* -------------------------*/

(exit = 1.)

(status in r0)

sys exit