mkdir LinuxKernel  #创建LinuxKernel根目录
cd ~/LinuxKernel/
wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.0.1.tar.xz #下载Linux内核，这里用的是5.0.1版本
xz -d linux-5.0.1.tar.xz #解压 
tar -xvf linux-5.0.1.tar 
cd linux-5.0.1

#如果已经安装过就忽略这一步
sudo apt-get install build-essential
sudo apt-get install libelf-dev
sudo apt-get install libncurses-dev
sudo apt-get install flex
sudo apt-get install bison
sudo apt-get install libssl-dev

#进入解压出来的目录
cd /linux-5.0.1/
#使用现存内核的配置文件：（xxx处使用TAB补全）
sudo cp /boot/config-xxx -r .config
#应用现存配置文件
sudo make oldconfig
#仅安装已有module
sudo make localmodconfig
#配置其他编译选项
sudo make menuconfig
#这个地方可能会报错
Your display is too small to run Menuconfig!
It must be at least 19 lines by 80 columns.
make[1]: *** [menuconfig] Error 1
make: *** [menuconfig] Error 2
这里需要点击Terminal->Preferences->Unnamed,然后将Initial terminal size，columns的数值增大,然后重新打开终端，执行命令

sudo make
#或者使用sudo make -j*,*位cpu核数

#安装modules
sudo make modules_install
#安装
sudo make install
#重启虚拟机
sudo shutdown -r now
#查看内核版本
uname -a

cd ~/LinuxKernel/
sudo apt install qemu#安装qemu命令
qemu-system-x86_64 -kernel linux-5.0.1/arch/x86_64/boot/bzImage

#创建MenuOS根目录
mkdir rootfs
#下载MenuOS
git clone https://github.com/mengning/menu.git

nslookup github.global.ssl.fastly.net
nslookup github.com
#这里会返回两个IP地址
sudo vim/etc/hosts
#按i进入插入模式，然后将xxxx   github.global.ssl.fastly.net  xxxx  github.com
添加至最后一行，然后按ESC,输入:wq!保存退出
sudo /etc/init.d/networking restart
#刷新DNS

cd menu
sudo apt-get install libc6-dev-i386#在64位环境下编译32位
#注意在初始化根目录之前要修改Makefile的内容，因为实验楼的系统是Linux 3.18.6，这里要改为5.0.1，修改之后如下
#qemu-system-x86_64 -kernel ../linux-5.0.1/arch/x86_64/boot/bzImage -initrd ../rootfs.img
#注意在Makefile修改命令时开头需加上TAB键，否则会报错
make rootfs

cd ~/LinuxKernel/ 
git clone https://github.com/mengning/linuxnet.git
cd linuxnet/lab2
make
cd ../../menu/#这里要修改Makefile文件
make rootfs

cd ~/LinuxKernel/
cd linuxnet/lab3
make rootfs#Make rootfs之前要修改Makefile
#未修改之前qemu -kernel ../../linux-3.18.6/arch/x86/boot/bzImage -initrd ../rootfs.img
#修改之后 qemu-system-x86_64 -kernel ../../linux-5.0.1/arch/x86/boot/bzImage -initrd ../rootfs.img

cd ~/LinuxKernel/menu
#先修改Makefile，在qemu-system-x86_64 -kernel ../linux-5.0.1/arch/x86_64/boot/bzImage -initrd ../rootfs.img
#末尾加上-append nokaslr -s -S
make rootfs

gdb
file ~/LinuxKernel/linux-5.0.1/vmlinux
target remote:1234
#设置断点对start_kernel进行跟踪
break start_kernel
c   #继续运行
list#查看上下文

break rest_init
c

asmlinkage __visible void __init start_kernel(void)
{
    char *command_line;
    char *after_dashes;

    set_task_stack_end_magic(&init_task);
    ...
    ...

  /* Do the rest non-__init‘ed, we‘re now alive */
    arch_call_rest_init();
}

noinline void __ref rest_init(void)
{
    struct task_struct *tsk;
    int pid;
    rcu_scheduler_starting();
    /*
     * We need to spawn init first so that it obtains pid 1, however
     * the init task will end up wanting to create kthreads, which, if
     * we schedule it before we create kthreadd, will OOPS.
     */
    pid = kernel_thread(kernel_init, NULL, CLONE_FS);
    rcu_read_lock();
    tsk = find_task_by_pid_ns(pid, &init_pid_ns);
    set_cpus_allowed_ptr(tsk, cpumask_of(smp_processor_id()));
    rcu_read_unlock();
    numa_default_policy();
    pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
    rcu_read_lock();
    kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
    rcu_read_unlock();
    system_state = SYSTEM_SCHEDULING;
    complete(&kthreadd_done);
    schedule_preempt_disabled();
    /* Call into cpu_idle with preempt disabled */
    cpu_startup_entry(CPUHP_ONLINE);
}