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