linux ko

15/12/2020 08:20

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文章出自个人博客https://applelin8.github.io/2020/12/15/linux-ko，转载请申明

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linux 系统ko模块编译。 note:

kernel dir
Makefile Kbuild Makefile 的一个最主要功能就是指定编译什么，这个功能是通过下面两个对象指定的obj-? 和$(module_name)-objs 例如：

   obj-y += example.o #编译o
   obj-m += $(module_name).o #编译ko
   $(module_name)-objs := a.o b.o c.o #编译基于的目标文件a.o b.o c.o

makefile的关键：

首先 obj-m指定模块名 $(module_name)，

   obj-m := $(module_name).o 

然后,

如果内核模块是通过几个源文件编译而成的,

再根据模块名$(name)-objs:=依赖的文件。

   $(module_name)-objs := a.o b.o c.o

Makefile example

   .PHONY: clean all

   #variable
   KDIR:=~/apple/kernel-4.15.4
   MAKE:=make
   name:=demo
   #$(info name=$(name))
   
   ifneq ($(KERNELRELEASE),)
   obj-m:=$(name).o
   $(name)-objs:= main.o hello.o
   endif
   
   #target
   all: demo
   
   demo:
   	#$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
   	$(MAKE) -C $(KDIR) M=$(PWD) modules
   	#sudo $(KDIR)/scripts/sign-file sha512 $(KDIR)/certs/signing_key.pem $(KDIR)/certs/signing_key.x509 $(name).ko
   	
   hello:
   	@echo hello
   
   clean:
   	$(MAKE) -C $(KDIR) M=$(PWD) clean

查看输出
```
dmesg | grep "keywords"
```

code

#ls demo
hello.c  hello.h  main.c  Makefile

hello.h

#ifndef _LINUX_HELLO_H_
#define _LINUX_HELLO_H_

void hello(void);

#endif

hello.c

#include "hello.h"
#include <linux/kernel.h>

void hello(void)
{
    printk("demo: hello\n");
    printk("demo: happy day!\n");
}

main.c

#include <linux/init.h>  
#include <linux/kernel.h>  
#include <linux/module.h> 
#include "hello.h"

static int demo_init(void)  
{  
    printk("demo: init module");
    hello();
    return 0;  
}  

static void demo_exit(void)  
{  
    printk("demo: exit module");  
    return;  
}  

module_init(demo_init);  
module_exit(demo_exit);  
MODULE_LICENSE("GPL");  
MODULE_AUTHOR("apple");

make

#cd demo
#make
make -C ~/apple/kernel-4.15.4 M=~/apple/project/module/demo modules
make[1]: Entering directory '~/apple/kernel-4.15.4'
  CC [M]  ~/apple/project/module/demo/main.o
  CC [M]  ~/apple/project/module/demo/hello.o
  LD [M]  ~/apple/project/module/demo/demo.o
  Building modules, stage 2.
  MODPOST 1 modules
  CC      ~/apple/project/module/demo/demo.mod.o
  LD [M]  ~/apple/project/module/demo/demo.ko
make[1]: Leaving directory '~/apple/kernel-4.15.4'

#ls ../demo
demo.ko  demo.mod.c  demo.mod.o  demo.o  hello.c  hello.h  hello.o  main.c  main.o  Makefile  modules.order  Module.symvers
#lsmod|grep demo
demo                   16384  0
#sudo rmmod demo
#sudo insmod demo.ko
#dmesg|grep demo
[ 2109.050790] demo: init module
[ 2109.050792] demo: hello
[ 2109.050793] demo: happy day!
#sudo rmmod demo
#dmesg|grep demo
[ 2123.678684] demo: exit module

make clean

#make clean
make -C ~/apple/kernel-4.15.4 M=~/apple/project/module/demo clean
make[1]: Entering directory '~/apple/kernel-4.15.4'
  CLEAN   ~/apple/project/module/demo/.tmp_versions
  CLEAN   ~/apple/project/module/demo/Module.symvers
make[1]: Leaving directory '~/apple/kernel-4.15.4'

linux ko

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