ref:https://pdos.csail.mit.edu/6.828/2020/xv6.html

实验：Lab: Xv6 and Unix utilities

环境搭建

实验环境搭建：https://blog.csdn.net/qq_45512097/article/details/126741793
搭建了1天，大家自求多福吧，哎。~搞环境真是折磨人
anyway，我搞好了：

开整实验

内容1：sleep

创建user/sleep.c
在Makefile中UPROGS下添加$U/_sleep
编写sleep.c
运行测试程序grade-lab-util并且指明要测试的函数。如 grade-lab-util sleep

#include "kernel/types.h"
#include "kernel/stat.h"
#include "user/user.h"void main(int argc, char *argv[])
{if(argc != 2){// 2 输出到哪里，输出内容，fprintf(2,"usage:sleep <time> \n");exit(1);}int sec = atoi(argv[1]);sleep(sec);  //printf("usage:sleep %d \n",sec);exit(0);
}

修改makefile，只需要改这一个地方

验证命令,要退出qume才能执行，否则会报错，
这种时候单项验证sleep

./grade-lab-util sleep

justin@DESKTOP-NIK28BI:~/vc6/xv6-labs-2020$ ./grade-lab-util sleep
fatal: detected dubious ownership in repository at '/mnt/d/code/vc6/xv6-labs-2020'
To add an exception for this directory, call:git config --global --add safe.directory /mnt/d/code/vc6/xv6-labs-2020
make: 'kernel/kernel' is up to date.
== Test sleep, no arguments == fatal: detected dubious ownership in repository at '/mnt/d/code/vc6/xv6-labs-2020'
To add an exception for this directory, call:git config --global --add safe.directory /mnt/d/code/vc6/xv6-labs-2020
sleep, no arguments: OK (1.3s)
== Test sleep, returns == sleep, returns: OK (0.8s)
== Test sleep, makes syscall == sleep, makes syscall: OK (1.0s)

内容2：pingpong

Write a program that uses UNIX system calls to ‘‘ping-pong’’ a byte between two processes over a pair of pipes, one for each direction.
The parent should send a byte to the child;
the child should print “: received ping”, where is its process ID, write the byte on the pipe to the parent（这里没有指定具体写什么内容，什么都可以，只是作为标志，且这个标志不需要也不要打印，否则会影响测评）, and exit;
the parent should read the byte from the child, print “: received pong”, and exit.
Your solution should be in the file user/pingpong.c.

#include "kernel/types.h"
#include "user/user.h"
#define RD 0 // pipe的read端
#define WR 1 // pipe的write端
int main(){char buf[10]; //缓冲区字符数组，存放传递的信息int fd_c2p[1]; // child->parentint fd_p2c[1]; // parent->childint ret1 = pipe(fd_c2p);int ret2 = pipe(fd_p2c);if(ret1==-1){printf("child->parent pipe");exit(1);}if(ret2==-1){printf("parent->child pipe");exit(1);}int pid = fork();if(pid==0){//子进程// 关闭父管道的写入端和子管道的读取端close(fd_p2c[WR]); // 显示关闭是为了严谨，不关闭不会报错close(fd_c2p[RD]); //read(fd_p2c[RD],buf,4);printf("child:%d received %s\n", getpid(),buf);write(fd_c2p[WR],"pong",4);}else if(pid>0){close(fd_p2c[RD]);close(fd_c2p[WR]);// 父进程write(fd_p2c[WR],"ping",4);int status;int child_id = wait(&status);printf("child:%d done!\n",child_id);read(fd_c2p[RD],buf,4);printf("parent:%d received %s\n", getpid(),buf);printf("parent:%d done!\n", getpid());}exit(0);return 0;
}

hart 1 starting
hart 2 starting
init: starting sh
$ pingpong
child:4 received ping
child:4 done!
parent:3 received pong
parent:3 done!

注意没有exit(0); 会出现乱码，原因未知,欢迎大神留言解惑：

hart 1 starting
hart 2 starting
init: starting sh
$ pingpong
child:4 received ping
usertrap(): unexpected scause 0x000000000000000d pid=4sepc=0x0000000000000100 stval=0x0000000000003f64
child:4 done!
parent:3 received pong
parent:3 done!
usertrap(): unexpected scause 0x000000000000000d pid=3sepc=0x0000000000000100 stval=0x0000000000003f64

ref：https://xv6.dgs.zone/labs/requirements/lab1.html