完全自动化-tree QEMU示例

https://github.com/******/linux-kernel-module-cheat/tree/753cbe68ff50bea0982e1791c8a2178a999d8377/buildroot_packages/kernel_modules

源代码树：

• buildroot / ：Buildroot 2017.02，理想情况下是git子模块


• kernel_module / ：带有某些模块的外部软件包
  
  
  
  • Config.in
  
  
  • external.mk
  
  
  • Makefile
  
  
  • hello.c ：hello world模块
  
  
  • buildroot/: Buildroot 2017.02, ideally as a git submodule
  • kernel_module/: external package with some modules
    • Config.in
    • external.mk
    • Makefile
    • hello.c: hello world module

    kernel_module / Config.in

    kernel_module/Config.in

    config BR2_PACKAGE_KERNEL_MODULE
            bool "kernel_module"
            depends on BR2_LINUX_KERNEL
            help
                    Linux Kernel Module Cheat.
    

    kernel_module / external.mk

    kernel_module/external.mk

    KERNEL_MODULE_VERSION = 1.0
    KERNEL_MODULE_SITE = $(BR2_EXTERNAL_KERNEL_MODULE_PATH)
    KERNEL_MODULE_SITE_METHOD = local
    $(eval $(kernel-module))
    $(eval $(generic-package))
    

    内核模块/ Makefile

    kernel_module/Makefile

    obj-m += $(addsuffix .o, $(notdir $(basename $(wildcard $(BR2_EXTERNAL_KERNEL_MODULE_PATH)/*.c))))
    ccflags-y := -DDEBUG -g -std=gnu99 -Wno-declaration-after-statement
    
    .PHONY: all clean
    
    all:
        $(MAKE) -C '$(LINUX_DIR)' M='$(PWD)' modules
    
    clean:
        $(MAKE) -C '$(LINUX_DIR)' M='$(PWD)' clean
    

    内核模块/hello.c

    kernel_module/hello.c

    #include <linux/module.h>
    #include <linux/kernel.h>
    
    MODULE_LICENSE("GPL");
    
    static int myinit(void)
    {
        printk(KERN_INFO "hello init\n");
        return 0;
    }
    
    static void myexit(void)
    {
        printk(KERN_INFO "hello exit\n");
    }
    
    module_init(myinit)
    module_exit(myexit)
    

    用法：

    cd buildroot
    make BR2_EXTERNAL="$(pwd)/../kernel_module" qemu_x86_64_defconfig
    echo 'BR2_PACKAGE_KERNEL_MODULE=y' >> .config
    make BR2_JLEVEL="$(($(nproc) - 2))" all
    qemu-system-x86_64 -M pc -kernel output/images/bzImage -drive file=output/images/rootfs.ext2,if=virtio,format=raw -append root=/dev/vda -net nic,model=virtio -net user
    

    QEMU打开，然后运行：

    QEMU opens up, then run:

    root
    modprobe hello
    modprobe -r hello
    

    dmesg 显示：

    hello init
    hello exit
    

    关键行是 $（eval $（kernel-module）） c> external.mk ，它为我们进行了所有设置，并安装了模块，其中 modprobe 将在其中找到它们（ / lib / modules / * / extra / hello.ko ），包括 modules.dep 用于模块间的依赖关系：如何从另一个模块调用导出的内核模块函数？

    The key line is $(eval $(kernel-module)) in external.mk, which sets everything up for us, and installs the modules where modprobe will find them (/lib/modules/*/extra/hello.ko), including modules.dep for inter-module dependencies: How to call exported kernel module functions from another module?

    如何GDB逐步调试内核模块：如何使用QEMU调试Linux内核模块？

    How to GDB step debug the kernel modules: How to debug Linux kernel modules with QEMU?

    To在启动时自动加载模块，请使用 BR2_ROOTFS_OVERLAY = ../ rootfs_overlay 和 rootfs_overlay / etc / init.d / S99modules 执行 modprobe 的文件。

    To autoload modules at startup, use BR2_ROOTFS_OVERLAY="../rootfs_overlay" and a rootfs_overlay/etc/init.d/S99modules file that does the modprobe.

    树内示例： https://github.com/******/buildroot/tree/9580078b98f885ca94e4dfc896265a8a491f6ae1

    In-tree example: https://github.com/******/buildroot/tree/9580078b98f885ca94e4dfc896265a8a491f6ae1 It is less clean, but also works.

    在Ubuntu 16.04主机上进行了测试。

    Tested on a Ubuntu 16.04 host.