编译内核模块的helloworld

http://www.tuicool.com/articles/jYreMf
树莓派编译网卡


编译内核模块的helloworld的例子如下
环境：
1.linode虚拟机
2.centos系统，其他系统都行
3.下面ibm的代码，sample.tar.gz
4.编译内核模块需要源码



参考链接
http://blog.csdn.net/tigerjb/article/details/6010997
http://www.ibm.com/developerworks/cn/linux/l-cn-kernelmodules/index.html
上代码

[root@li408-34 hello]# cat hello.c 
/*                                                     
 * $Id: hello.c,v 1.5 2004/10/26 03:32:21 corbet Exp $ 
 * The code samples are covered by a dual BSD/GPL license from
 * Linux Device Drivers, Third Edition, by Jonathan Corbet, 
 * Alessanfdro Rubini, and Greg Kroah-Hartman.Copyright
 * 2005 O鈥橰eilly Media, Inc., 0-596-00590-3.
 */                                                    
#include <linux/init.h>
#include <linux/module.h>
MODULE_LICENSE("Dual BSD/GPL");

static int hello_init(void)
{
        printk(KERN_ALERT "Hello, haoning-------------\n");
        return 0;
}

static void hello_exit(void)
{
        printk(KERN_ALERT "Goodbye, cruel world\n");
}

module_init(hello_init);
module_exit(hello_exit);

Makefile

[root@li408-34 hello]# cat Makefile 

# 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 \
        *.order *.symvers

.PHONY: modules modules_install clean

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

★★★★★★★★★★★★★★★我是罪恶的分割线★★★★★★★★★★★
步骤：
环境linode
centos6

[root@li408-34 hello]# uname -a
Linux li408-34 3.8.4-linode50 #1 SMP Mon Mar 25 15:50:29 EDT 2013 i686 i686 i386 GNU/Linux
[root@li408-34 hello]# uname -r
3.8.4-linode50
[root@li408-34 hello]# 

由于linode的内核都是自己编译的
上网查了一些自己编译内核的方法，但是还是启动报错
参考http://www.xiaozhou.net/ittech/vps-ittech/upgrade_linode_vps_kernel_manually-2011-04-28.htm
★这个写得很好，学习了

后来自己下了

linux-3.8.tar.xz
xz -d linux-3.8.tar.xz
tar xvf linux-3.8.tar
cd  linux-3.8
cp /proc/config.gz .
gunzip config.gz 
mv config .config

这一步是用系统当前的config文件
作为内核的make menuconfig或者make config产生的文件
配置项太jb多了
然后可能需要改

CONFIG_PARAVIRT_GUEST=y
CONFIG_XEN=y
CONFIG_PARAVIRT=y
CONFIG_PARAVIRT_CLOCK=y
CONFIG_XEN_BLKDEV_FRONTEND=y
CONFIG_XEN_NETDEV_FRONTEND=y
CONFIG_HVC_XEN=y
CONFIG_XEN_SCRUB_PAGES=y

CONFIG_NETFILTER_XT_MATCH_CONNLIMIT=y

CONFIG_IP_NF_SECURITY=n

CONFIG_IP6_NF_SECURITY=n

#rm -rf /boot/*  看好了，这里可能原来就有启动的东西了，还是别删了
#开始编译
make modules
make
#安装内核
make install
make modules_install

然后就会在/boot下面生成vmlinuz System.map
据说改了 /boot/grub/menu.lst重新启动 ，linode选pv-grub-x86-32
就能重新启动使用新内核了，但是我没试验成功，反正我是为了编译内核模块，又不是重新然linode好使，可能虚拟机还是和真实机器有莫名其买的差距吧，没深究

继续编译内核模块：

ln -s /root/kernel/linux-3.8 /lib/modules/3.8.4-linode50/build 

把新编译的源码链接到 系统已经存在的内核源码
其实不太对，但是两个都是3.8的差别还不算大，内核模块可用

回到罪恶的分割线上面的代码

[root@li408-34 hello]# ls
Makefile  hello.c
[root@li408-34 hello]# pwd
/root/kk/samples/hello
[root@li408-34 hello]#

[root@li408-34 hello]# make
make -C /lib/modules/3.8.4-linode50/build M=/root/kk/samples/hello modules
make[1]: Entering directory `/root/kernel/linux-3.8'
  CC [M]  /root/kk/samples/hello/hello.o
  Building modules, stage 2.
  MODPOST 1 modules
  CC      /root/kk/samples/hello/hello.mod.o
  LD [M]  /root/kk/samples/hello/hello.ko
make[1]: Leaving directory `/root/kernel/linux-3.8'
[root@li408-34 hello]# 

[root@li408-34 hello]# lsmod
Module                  Size  Used by
[root@li408-34 hello]# 
[root@li408-34 hello]# ls     
Makefile  Module.symvers  hello.c  hello.ko  hello.mod.c  hello.mod.o  hello.o  modules.order
[root@li408-34 hello]# insmod hello.ko
[root@li408-34 hello]# lsmod
Module                  Size  Used by
hello                    606  0 
[root@li408-34 hello]# 
[root@li408-34 hello]# cat /proc/modules
hello 606 0 - Live 0xede36000 (O)
[root@li408-34 hello]#
[root@li408-34 hello]# cd /sys/module/hello
[root@li408-34 hello]# ls
coresize  holders  initsize  initstate  notes  refcnt  sections  taint  uevent
[root@li408-34 hello]# tree -a
.
|-- coresize
|-- holders
|-- initsize
|-- initstate
|-- notes
|   `-- .note.gnu.build-id
|-- refcnt
|-- sections
|   |-- .gnu.linkonce.this_module
|   |-- .note.gnu.build-id
|   |-- .rodata.str1.1
|   |-- .strtab
|   |-- .symtab
|   `-- .text
|-- taint
`-- uevent

3 directories, 13 files
[root@li408-34 hello]# dmesg
.....
Hello, world
Goodbye, cruel world
[root@li408-34 hello]# tail -f /var/log/messages
Apr 11 11:37:59 li408-34 abrtd: Init complete, entering main loop
Apr 11 11:37:59 li408-34 init: Failed to spawn hvc0 main process: unable to execute: No such file or directory
Apr 11 11:42:23 li408-34 kernel: Hello, haoning-------------
Apr 11 11:43:56 li408-34 kernel: Goodbye, cruel world
Apr 11 11:44:12 li408-34 kernel: Hello, haoning-------------
Apr 11 13:51:49 li408-34 kernel: Goodbye, cruel world
Apr 11 13:51:59 li408-34 kernel: Hello, haoning-------------
Apr 11 14:44:21 li408-34 yum[4371]: Installed: tree-1.5.3-2.el6.i686
Apr 11 15:05:21 li408-34 kernel: Goodbye, cruel world
Apr 11 15:05:51 li408-34 kernel: Hello, world

表示内核已经正确装载了
lsmod查看模块
rmmod 删除模块

把上面ibm的的代码放到附件里了