Construct a simple Linux system menuos

Chen Zhiwei 20135125

Original works reproduced please indicate the source

"Linux kernel Analysis" MOOC course http://mooc.study.163.com/course/USTC-1000029000

Experimental guidance

Open the shell using the virtual machine of the lab building:

1. CD linuxkernel/
2. Qemu-kernel linux-3.18.6/arch/x86/boot/bzimage -initrd rootfs.img

Debug kernel with GDB trace

1. Qemu-kernel linux-3.18.6/arch/x86/boot/bzimage -initrd rootfs.img-s -S # Description of the-s and-s options:
2. #-S Freeze CPU at startup (with ' C ' to start execution)
3. #-S Shorthand for-gdb tcp::1234 If you do not want to use port 1234, you can use-GDB tcp:xxxx to replace the-s option

Open another Shell window

1. gdb
2. file  Linux-3.18.6/vmlinux #  in GdB interface targe  Remote before loading symbol table
3. (GDB) Target remote:1234 #  establish a connection between GDB and Gdbserver, press c  Let Linux on Qemu continue to run
4. break start_kernel #  Breakpoints can be set before Target remote, or after

Understanding and experience of experimental results:

After analyzing the Start_kernel () function, I found that Start_kernel () called a series of initialization functions to complete the kernel itself. These actions are public, and others need to be configured to execute.

As the Monensin teacher said, the Start_kernel () function is equivalent to the MAIN.C function in the C language function, and Start_kernel () will persist after startup and Rest_init in Kernel_init and create process number 1th. That is, the INIT process, the first user-state process.

Construct a simple Linux system menuos