《Linux内核分析》之构造一个简单的Linux系统MenuOS 实验总结

1
# 下载内核源代码编译内核
2
cd ~/LinuxKernel/
3
wget https://www.kernel.org/pub/linux/kernel/v3.x/linux-3.18.6.tar.xz
4
xz -d linux-3.18.6.tar.xz
5
tar -xvf linux-3.18.6.tar
6
cd linux-3.18.6
7
make i386_defconfig
8
make # 一般要编译很长时间，少则20分钟多则数小时
9

10
# 制作根文件系统
11
cd ~/LinuxKernel/
12
mkdir rootfs
13
git clone  https://github.com/mengning/menu.git
14
cd menu
15
gcc -o init linktable.c menu.c test.c -m32 -static –lpthread
16
cd ../rootfs
17
cp ../menu/init ./
18
find . | cpio -o -Hnewc |gzip -9 > ../rootfs.img
19

20
# 启动MenuOS系统
21
cd ~/LinuxKernel/
22
qemu -kernel linux-3.18.6/arch/x86/boot/bzImage -initrd rootfs.img

1
asmlinkage __visible void __init start_kernel(void)
2
{
3
.......
4
/*init_task即手工创建的PCB，0号进程就是最终的idle进程*/
5
set_task_stack_end_magic(&init_task);
6
........
7
/*初始化中断向量*/
8
trap_init();
9
/*内存管理模块初始化*/
10
mm_init();
11
/*调度模块初始化*/
12
sched_init();
13
....
14
/*其他初始化*/
15
rest_init()
16
}

1
static noinline void __init_refok rest_init(void)
2
{
3
        int pid;
4

5
        rcu_scheduler_starting();
6
        /*
7
         * We need to spawn init first so that it obtains pid 1, however
8
         * the init task will end up wanting to create kthreads, which, if
9
         * we schedule it before we create kthreadd, will OOPS.
10
         */
11
        /*初始化了第一个用户态的进程1号进程*/
12
        kernel_thread(kernel_init, NULL, CLONE_FS);
13
        numa_default_policy();
14
        /*创建内核线程管理系统资源
15
         *kthreadd 为内核线程
16
         */
17
        pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
18
        rcu_read_lock();
19
        kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
20
        rcu_read_unlock();
21
        complete(&kthreadd_done);
22

23
        /*
24
         * The boot idle thread must execute schedule()
25
         * at least once to get things moving:
26
         */
27
        init_idle_bootup_task(current);
28
        schedule_preempt_disabled();
29
        /* Call into cpu_idle with preempt disabled */
30
        cpu_startup_entry(CPUHP_ONLINE);
31
}