带参数到内核模块

hellop.c 文件内容如下：

/*
 * $Id: hellop.c,v 1.4 2004/09/26 07:02:43 gregkh Exp $
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>

MODULE_LICENSE("Dual BSD/GPL");

/*
 * These lines, although not shown in the book,
 * are needed to make hello.c run properly even when
 * your kernel has version support enabled
 */


/*
 * A couple of parameters that can be passed in: how many times we say
 * hello, and to whom.
 */
static char *whom = "world";
static int howmany = 1;
module_param(howmany, int, S_IRUGO);
module_param(whom, charp, S_IRUGO);

static int hello_init(void)
{
        int i;
        for (i = 0; i < howmany; i++)
                printk(KERN_ALERT "(%d) Hello, %s\n", i, whom);
        return 0;
}
static void hello_exit(void)
{
        printk(KERN_ALERT "Goodbye, cruel world\n");
}

module_init(hello_init);
module_exit(hello_exit);

Makefile 文件内容如下：

# To build modules outside of the kernel tree, we run "make"
# in the kernel source tree; the Makefile these then includes this
# Makefile once again.
# This conditional selects whether we are being included from the
# kernel Makefile or not.
ifeq ($(KERNELRELEASE),)

# Assume the source tree is where the running kernel was built
# You should set KERNELDIR in the environment if it's elsewhere
KERNELDIR ?= /lib/modules/$(shell uname -r)/build
# The current directory is passed to sub-makes as argument
PWD := $(shell pwd)

modules:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules

modules_install:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install

clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions

.PHONY: modules modules_install clean

else
# called from kernel build system: just declare what our modules are
obj-m := hellop.o
endif

$ make  编译
$ sudo insmod hellop.ko howmany=10 whom="Tom"  加载模块

在/var/log/syslog中打印信息如下：

Jun 21 16:12:33 eric-Inspiron-530 kernel: [23155.364464] (0) Hello, Tom
Jun 21 16:12:33 eric-Inspiron-530 kernel: [23155.364468] (1) Hello, Tom
Jun 21 16:12:33 eric-Inspiron-530 kernel: [23155.364470] (2) Hello, Tom
Jun 21 16:12:33 eric-Inspiron-530 kernel: [23155.364471] (3) Hello, Tom
Jun 21 16:12:33 eric-Inspiron-530 kernel: [23155.364473] (4) Hello, Tom
Jun 21 16:12:33 eric-Inspiron-530 kernel: [23155.364474] (5) Hello, Tom
Jun 21 16:12:33 eric-Inspiron-530 kernel: [23155.364476] (6) Hello, Tom
Jun 21 16:12:33 eric-Inspiron-530 kernel: [23155.364477] (7) Hello, Tom
Jun 21 16:12:33 eric-Inspiron-530 kernel: [23155.364479] (8) Hello, Tom
Jun 21 16:12:33 eric-Inspiron-530 kernel: [23155.364480] (9) Hello, Tom