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
[code="java"]
# 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);
[/code]
Makefile
[code="java"]# 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
[/code]
★★★★★★★★★★★★★★★我是罪恶的分割线★★★★★★★★★★★
步骤：
环境linode
centos6
[code="java"]
# uname -a
Linux li408-34 3.8.4-linode50 #1 SMP Mon Mar 25 15:50:29 EDT 2013 i686 i686 i386 GNU/Linux
# uname -r
3.8.4-linode50
#
[/code]

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

[color=red]这一步是用系统当前的config文件
作为内核的make menuconfig或者make confi*生的文件
配置项太jb多了
然后可能需要改[/color]

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
[code="java"]
# ls
Makefile hello.c
# pwd
/root/kk/samples/hello
#
[/code]
[code="java"]
# 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'
#
[/code]

[code="java"]
# lsmod
Module Size Used by
#
# ls
Makefile Module.symvers hello.c hello.ko hello.mod.c hello.mod.o hello.o modules.order
# insmod hello.ko
# lsmod
Module Size Used by
hello 606 0
#
# cat /proc/modules
hello 606 0 - Live 0xede36000 (O)
#
# cd /sys/module/hello
# ls
coresize holders initsize initstate notes refcnt sections taint uevent
# 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
# dmesg
.....
Hello, world
Goodbye, cruel world
# 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

[/code]
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