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发信人: chenl (bigmouth), 信区: Linux
标  题: Re: 请熟悉汇编的大峡帮忙！！！！
发信站: BBS 水木清华站 (Sat Aug  7 09:10:28 1999) WWW-POST

【在 xtime (逝者) 的大作中提到: 】
∶ 下面是Linux进程切换的原代码：
∶ #define switch_to(prev,next) do { \
∶ __asm__("movl %2,"SYMBOL_NAME_STR(current_set)"\n\t" \
In c: current_set=next;
      __asm longjump (*(((char*(&next->tss.tr)-4))
/* swith the task, refer to the i386 task switch */
∶         "ljmp %0\n\t" \
∶         "cmpl %1,"SYMBOL_NAME_STR(last_task_used_math)"\n\t" \
if(last_task_used_math_coprocessor){
save all debug register for the
process "prev"
use loaddebug();
}
return;
wish this could give u help.

∶         "jne 1f\n\t" \
∶         "clts\n" \
∶         "1:" \
∶         : /* no outputs */ \
∶         :"m" (*(((char *)&next->tss.tr)-4)), \
∶         "r" (prev), "r" (next)); \
∶         /* Now maybe reload the debug registers */ \
∶         if(prev->debugreg[7]){ \
∶                 loaddebug(prev,0); \
∶                 loaddebug(prev,1); \
∶                 loaddebug(prev,2); \
∶                 loaddebug(prev,3); \
∶                 loaddebug(prev,6); \
∶         } \
∶ } while (0)
∶ 恳请大峡给予增援！向小生讲解以下该函数的大体意思。

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