Makefile内容
KVERS = $(shell uname -r)
# Kernel modules
obj-m += book.o
# Specify flags for the module compilation.
#EXTRA_CFLAGS=-g -O0
build: kernel_modules
kernel_modules:
make -C /lib/modules/$(KVERS)/build M=$(CURDIR) modules
clean:
make -C /lib/modules/$(KVERS)/build M=$(CURDIR) clean
book.c内容--使用宋老师的例子
* a simple kernel module supporting parameters
*
* Copyright (C) 2014 Barry Song (baohua@kernel.org)
*
* Licensed under GPLv2 or later.
*/
#include <linux/init.h>
#include <linux/module.h>
static char *book_name = "dissecting Linux Device Driver";
module_param(book_name, charp, S_IRUGO);
static int book_num = 4000;
module_param(book_num, int, S_IRUGO);
static int __init book_init(void)
{
printk(KERN_INFO "book name:%s\n", book_name);
printk(KERN_INFO "book num:%d\n", book_num);
return 0;
}
module_init(book_init);
static void __exit book_exit(void)
{
printk(KERN_INFO "book module exit\n ");
}
module_exit(book_exit);
MODULE_AUTHOR("Barry Song <baohua@kernel.org>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("A simple Module for testing module params");
MODULE_VERSION("V1.0");
默认加载
sudo insmod book.ko
输出如下
[41709.146814] book name:dissecting Linux Device Driver
[41709.146818] book num:4000
加载时传递参数
sudo insmod book.ko book_name='GoodBook' book_num=5000
输出如下
[41933.147764] book name:GoodBook
[41933.147769] book num:5000
加载时传递参数--字符串里包含空格（错误方式）
sudo insmod book.ko book_name='Professional Linux Kernel Architecture' book_num=5000
或者
sudo insmod book.ko book_name="Professional Linux Kernel Architecture" book_num=5000
提示错误
insmod: ERROR: could not insert module book.ko: Unknown symbol in module
dmesg输出
[42208.316805] book: Unknown parameter `Linux'
原因在于：shell将' '或" "吃掉了，剩下book_name=Professional Linux Kernel Architecture作为参数传递给内核，由内核函数parse_args进行解析[kernel/params.c]，然后调用next_arg将其分割为param和val匹配对，以等号作为分割符号，next_arg函数如下（[kernel/params.c]）：
/* You can use " around spaces, but can't escape". /
/ Hyphens and underscores equivalent in parameter names. */
static char *next_arg(char *args, char **param, char **val)
{
unsigned int i, equals = 0;
int in_quote = 0, quoted = 0;
char *next;
if (*args == '"') {/* 出现双引号 */
args++;
in_quote = 1;
quoted = 1;
}
for (i = 0; args[i]; i++) {
if (isspace(args[i]) && !in_quote)
break; /* 无双引号配对后出现空格时跳出for循环 */
if (equals == 0) {
if (args[i] == '=')
equals = i;/* 出现等号后记录其位置 */
}
if (args[i] == '"')/* 判断双引号" */
in_quote = !in_quote;/* 双引号必须配对使用 */
}
*param = args;
if (!equals)
*val = NULL;/* 无等号出现时赋值为空， */
else {
args[equals] = '\0';
*val = args + equals + 1;/* 指向配对字符串的开始位置*/
/* Don't include quotes in value. */
if (**val == '"') {
(*val)++;
if (args[i-1] == '"')
args[i-1] = '\0';
}
if (quoted && args[i-1] == '"')
args[i-1] = '\0';
}
if (args[i]) {
args[i] = '\0';
next = args + i + 1;
} else
next = args + i;
/* Chew up trailing spaces. */
return skip_spaces(next);
}
根据上面函数分析，需要将传递给kernel时包括双引号内的内容是可以包含空格的，因此insmod时将"Professional Linux Kernel Architecture"外再用单引号包裹一层传递给shell即：'"Professional Linux Kernel Architecture"'，最后传递给kernel时变成"Professional Linux Kernel Architecture"，kernel即可正常识别。
加载时传递参数--字符串里包含空格(正确方式)
sudo insmod book.ko book_name='"Professional Linux Kernel Architecture"' book_num=5000
输出
[45955.423536] book name:Professional Linux Kernel Architecture
[45955.423540] book num:5000
