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分享linux驱动模块编译安装时，makefile出现的问题
系统为ubuntu kylin 15.10，内核版本4.2.0-27
自己编译安装一个字符驱动模块，驱动源码如下：
同时，自己编写的Makefile如下
第一次写makefile，开始不知道要注意tab键，折腾了半天才明白。但是编译的时候还是出错：
新手在这里求问了。
自己编译安装一个字符驱动模块，驱动源码如下：
my_chrdev.c
#include <linux/init.h>//初始化头文件
#include <linux/module.h>//动态的将模块加载到内核中去常用的宏定义如 MODULE_LICESENCE(),MODULE_AUTHOR(),
#include <linux/kernel.h>
#include <linux/cdev.h>//包含了cdev 结构及相关函数的定义
#include <linux/types.h>//对一些特殊类型的定义，例如dev_t, off_t, pid_t
#include <linux/fs.h> //包含文件操作相关struct的定义，例struct file_operations
#include <linux/errno.h>//包含了对返回值的宏定义，这样用户程序可以用perror输出错误信息。
#include <linux/sched.h>//内核等待队列中要使用的TASK_NORMAL、TASK_INTERRUPTIBLE包含在这个头文件
#include <linux/mm.h>//内存管理头文件，含有页面大小定义和一些页面释放函数原型
#include <linux/slab.h>//包含了kcalloc、kzalloc内存分配函数的定义
#include <asm/io.h>//I/O头文件，以宏的嵌入汇编程序形式定义对I/O端口操作的函数
#include <asm/system.h>//系统头文件，定义了设置或修改描述符/中断门等的嵌入式汇编宏
#include <asm/uaccess.h>//与处理器相关的入口
#define MY_CHRDEV_SIZE 1024 //设备申请的内存空间1k
struct cdev cdev; //字符设备结构体
static int mychrdev_major=0; //主设备号变量
struct Device
{
char *data; //char数组指针，用于存放从用户读入的数据
long data_size; //存储的数据长度
} *pdev;
static int my_open(struct inode *inode, struct file *file)
{
file->private_data = pdev;
return 0;
}
static loff_t my_llseek(struct file *file, loff_t offset, int orig)
{
loff_t cfo=0; //current file offset
switch(orig)
{
case 0: cfo = offset; //SEEK_SET
break;
case 1: cfo = file->f_pos + offset; //SEEK_CUR
break;
case 2: cfo = MY_CHRDEV_SIZE - 1 + offset; //SEEK_END
break;
}
if ((cfo < 0) || (cfo > MY_CHRDEV_SIZE))
{
return -EINVAL;
}
file->f_pos = cfo;
return cfo;
}
//对应用户态的read,写数据到用户空间
static ssize_t my_read(struct file *file, const char __user *buf,
size_t count, loff_t *p_cfo)
{
int val=0;
struct Device *dev = file->private_data;//设备描述结构体指针,获取设备信息
if(copy_to_user(buf, (void *)(dev->data + *p_cfo), count))
val = -EFAULT;
else
{
*p_cfo += count;
val = count;
}
return val;
}
//对应用户态的write,从用户空间读入数据
static ssize_t my_write(struct file *file, const char __user *buf,
size_t count,loff_t *p_cfo)
{
int val = 0;
struct Device *dev = file->private_data;
if(copy_from_user(dev->data + *p_cfo), buf, count))
val = -EFAULT;
else
{
*p_cfo += count;
val = count;
}
return val;
}
struct int file_operations fops =
{
.owner = THIS_MODULE,
.llseek = my_llseek,
.read = my_read,
.write = my_write;
.open = my_open,
}
int __init init_module(void)
{
int dev_no;
if((dev_no= register_chrdev(0, "MyChrDev", &fops) < 0)
{
printk(KERN_INFO "MyChrDev: Fail to get major num.\n");
return dev_no;
}
if(mychrdev_major == 0)
mychrdev_major = dev_no;
cdev_init(&cdev, &fops);
cdev.owner = THIS_MODULE;
cdev.ops = &fops;
cdev_add(&cdev, MKDEV(mychrdev_major, 0), 1); //注册1个字符设备
//为设备描述结构体分配内存
pdev = kmalloc(sizeof(struct Device), GFP_KERNEL);
if(!pdev)
{
dev_no = -ENOMEM;
printk(KERN_INFO "MyChrDev: Fail to get memory.\n");
return dev_no;
}
(*pdev).size = MY_CHRDEV_SIZE;
(*pdev).data = kmalloc(MY_CHRDEV_SIZE, GFP_KERNEL);
memset((*pdev).data, 0, (*pdev).size);
return 0;
}
void __exit cleanup_module(void)
{
cdev_del(&cdev);//注销设备
kfree(pdev);//注销设备结构体
kfree((*pdev).data);//注销设备内存空间
unregister_chrdev(mychrdev_major, "MyChrDev");//卸载主设备号
}
MODULE_LICESENCE("Dual BSD/GLPL");
MODULE_AUTHOR("Lipeng Wan");
module_init(init_module);
module_exit(cleanup_module);
同时，自己编写的Makefile如下
ifneq ($(KERNELRELEASE),)
#kbuild syntax
#the source file
mymodule-objs := my_chrdev.o
#the target file
obj-m := my_chrdev.o
else
#def some macros
PWD := $(shell pwd)
KVER ?= $(shell uname -r)
KDIR := /lib/modules/$(KVER)/build
all:
$(MAKE) -C $(KDIR) M=$(PWD)
clean:
rm -rf .*.cmd *.o *.mod.c *.ko .tmp_versions
endif
第一次写makefile，开始不知道要注意tab键，折腾了半天才明白。但是编译的时候还是出错：
Makefile:1: *** recipe commences before first target。 停止。新手在这里求问了。
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lipv 2016-02-27
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ifneq ($(KERNELRELEASE),)
#kbuild syntax
#the source file
mymodule-objs := my_chrdev.o
#the target file
obj-m := my_chrdev.o
else
#def some macros
PWD := $(shell pwd)
KVER ?= $(shell uname -r)
KDIR := /lib/modules/$(KVER)/build
all:
$(MAKE) -C $(KDIR) M=$(PWD)
clean:
rm -rf .*.cmd *.o *.mod.c *.ko .tmp_versions
endif
就是上面第一个makefile
lipv 2016-02-27
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没注意这个tab，但是没有出现之前的错误了，成功产生.ko文件
nswcfd 2016-02-26
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出现recipe commences before first target的时候的makefile的确切内容是什么？（注意排除粘贴的影响）
nswcfd 2016-02-26
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贴的有问题吧？
如果把#ifneq, #else, #endif之前的注释去掉的话，endif前面有个tab，属于clean target的一部分，导致整个makefile由于缺少endif不完整？
图灵转世 2016-02-24
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网上百度一下，应该可以解决额，
nswcfd 2016-02-23
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估计还是tab引起的问题
http://www.gnu.org/software/make/manual/html_node/Error-Messages.html
‘recipe commences before first target. Stop.’
‘missing rule before recipe. Stop.’
This means the first thing in the makefile seems to be part of a recipe: it begins with a recipe prefix character and doesn’t appear to be a legal make directive (such as a variable assignment). Recipes must always be associated with a target.
The second form is generated if the line has a semicolon as the first non-whitespace character; make interprets this to mean you left out the "target: prerequisite" section of a rule. See Rule Syntax.
http://www.gnu.org/software/make/manual/html_node/Recipe-Syntax.html
5.1 Recipe Syntax
Makefiles have the unusual property that there are really two distinct syntaxes in one file. Most of the makefile uses make syntax (see Writing Makefiles). However, recipes are meant to be interpreted by the shell and so they are written using shell syntax. The make program does not try to understand shell syntax: it performs only a very few specific translations on the content of the recipe before handing it to the shell.
Each line in the recipe must start with a tab (or the first character in the value of the .RECIPEPREFIX variable; see Special Variables), except that the first recipe line may be attached to the target-and-prerequisites line with a semicolon in between. Any line in the makefile that begins with a tab and appears in a “rule context” (that is, after a rule has been started until another rule or variable definition) will be considered part of a recipe for that rule. Blank lines and lines of just comments may appear among the recipe lines; they are ignored.
Some consequences of these rules include:
A blank line that begins with a tab is not blank: it’s an empty recipe (see Empty Recipes).
A comment in a recipe is not a make comment; it will be passed to the shell as-is. Whether the shell treats it as a comment or not depends on your shell.
A variable definition in a “rule context” which is indented by a tab as the first character on the line, will be considered part of a recipe, not a make variable definition, and passed to the shell.
A conditional expression (ifdef, ifeq, etc. see Syntax of Conditionals) in a “rule context” which is indented by a tab as the first character on the line, will be considered part of a recipe and be passed to the shell.
nswcfd 2016-02-23
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语法上倒是没有什么问题。
lipv 2016-02-23
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#ifneq ($(KERNELRELEASE),)
#kbuild syntax
#the source file
mymodule-objs := my_chrdev.o
#the target file
obj-m := my_chrdev.o
#else
#def some macros
PWD := $(shell pwd)
KVER := $(shell uname -r)
KDIR := /lib/modules/$(KVER)/build
all:
$(MAKE) -C $(KDIR) M=$(PWD)
clean:
rm -rf .*.cmd *.o *.mod.c *.ko .tmp_versions
#endif
常书 2016-02-22
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不是的，KDIR是你放内核的目录，用下面这种方式编译的话
上上面的的编译就要拷贝到内核目录去编译
你内核没编译过，编译驱动会报错的
lipv 2016-02-22
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是直接把makefile和.c文件复制过去，存放在一个文件夹里，切换到文件夹目录进行编译么？试了，还是那个错误！
lipv 2016-02-22
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内核是编译过了的，有两个内核：linux-4.2.0 和4.2.0.7。用gcc直接编译时，提示找不到linux/module.h, linux/init.h头文件也有问题。
常书 2016-02-22
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到/lib/modules/$(KVER)/build这里编译一下
常书 2016-02-22
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内核先编译再编译你的模块
