ucore_LAB5实验的报告.doc

LAB5实验报告 实验目的： 了解第一个用户进程创建过程 了解系统调用框架的实现机制 了解ucore如何实现系统调用sys_fork/sys_exec/sys_exit/sys_wait来进行进程管理 实验内容： 实验4完成了内核线程，但到目前为止，所有的运行都在内核态执行。实验5将创建用户进程，让用户进程在用户态执行，且在需要ucore支持时，可通过系统调用来让ucore提供服务。为此需要构造出第一个用户进程，并通过系统调用sys_fork/sys_exec/sys_exit/sys_wait来支持运行不同的应用程序，完成对用户进程的执行过程的基本管理。 练习 练习0：填写已有实验 根据提示，对标注LAB5 YOUR CODE : (update LAB4 steps)的部分进行一定的改动。 Kern/trap/trap.c: /* LAB1 YOUR CODE : STEP 3 */ /* handle the timer interrupt */ /* (1) After a timer interrupt, you should record this event using a global variable (increase it), such as ticks in kern/driver/clock.c * (2) Every TICK_NUM cycle, you can print some info using a funciton, such as print_ticks(). * (3) Too Simple? Yes, I think so! */ /* LAB5 YOUR CODE */ /* you should upate you lab1 code (just add ONE or TWO lines of code): * Every TICK_NUM cycle, you should set current processs current-need_resched = 1 */ ticks ++; if (ticks % TICK_NUM == 0) { assert(current != NULL); current-need_resched = 1; } /* LAB1 YOUR CODE : STEP 2 */ /* (1) Where are the entry addrs of each Interrupt Service Routine (ISR)? * All ISRs entry addrs are stored in __vectors. where is uintptr_t __vectors[] ? * __vectors[] is in kern/trap/vector.S which is produced by tools/vector.c * (try make command in lab1, then you will find vector.S in kern/trap DIR) * You can use extern uintptr_t __vectors[]; to define this extern variable which will be used later. * (2) Now you should setup the entries of ISR in Interrupt Description Table (IDT). * Can you see idt[256] in this file? Yes, its IDT! you can use SETGATE macro to setup each item of IDT * (3) After setup the contents of IDT, you will let CPU know where is the IDT by using lidt instruction. * You dont know the meaning of this instruction? just google it! and check the libs/