linux 驱动开发

1.安装 linux
2.写 hello world
//hello.c

 #include <linux/kernel.h> /*Needed by all modules*/
#include <linux/module.h> /*Needed for KERN_* */
#include <linux/init.h> /* Needed for the macros */

MODULE_LICENSE("GPL");

static int year=2014;

static int hello_init(void)
{
  printk(KERN_WARNING "Hello kernel, it's %d!\n",year);
  return 0;
}

static void hello_exit(void)
{
  printk("Bye, kernel!\n");
}

/* main module function*/
module_init(hello_init);
module_exit(hello_exit);

obj-m := hello.o 表示编译成模块，后面写对应文件名称加.o
Makefile

 obj-m  := hello.o

KERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD       := $(shell pwd)

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

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

安装模块命令 insmod ./hello.ko
删除 rmmod ./hello.ko
用命令 tail /var/log/kern.log查看日志

 root@ubuntu:~/Desktop# make
make -C /lib/modules/4.2.0-27-generic/build M=/root/Desktop
make[1]: Entering directory `/usr/src/linux-headers-4.2.0-27-generic'
  LD      /root/Desktop/built-in.o
  CC [M]  /root/Desktop/hello.o
  Building modules, stage 2.
  MODPOST 1 modules
  CC      /root/Desktop/hello.mod.o
  LD [M]  /root/Desktop/hello.ko
make[1]: Leaving directory `/usr/src/linux-headers-4.2.0-27-generic'
root@ubuntu:~/Desktop# insmod ./hello.ko
root@ubuntu:~/Desktop# tail /var/log/kern.log
Aug 26 05:54:38 ubuntu kernel: [   11.882941] audit: type=1400 audit(1535288078.331:11): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/lib/lightdm/lightdm-guest-session" pid=825 comm="apparmor_parser"
Aug 26 05:54:38 ubuntu kernel: [   12.138198] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
Aug 26 05:54:38 ubuntu kernel: [   12.423300] e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
Aug 26 05:54:38 ubuntu kernel: [   12.436023] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
Aug 26 05:55:05 ubuntu kernel: [   39.322268] audit_printk_skb: 150 callbacks suppressed
Aug 26 05:55:05 ubuntu kernel: [   39.322272] audit: type=1400 audit(1535288105.459:62): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/lib/cups/backend/cups-pdf" pid=2171 comm="apparmor_parser"
Aug 26 05:55:05 ubuntu kernel: [   39.322282] audit: type=1400 audit(1535288105.459:63): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2171 comm="apparmor_parser"
Aug 26 05:55:05 ubuntu kernel: [   39.322809] audit: type=1400 audit(1535288105.459:64): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2171 comm="apparmor_parser"
Aug 26 06:15:14 ubuntu kernel: [ 1248.118385] hello: module verification failed: signature and/or required key missing - tainting kernel
Aug 26 06:15:14 ubuntu kernel: [ 1248.121354] Hello kernel, it's 2014!
root@ubuntu:~/Desktop# rmmod ./hello.ko 
root@ubuntu:~/Desktop# tail /var/log/kern.log
Aug 26 05:54:38 ubuntu kernel: [   12.138198] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
Aug 26 05:54:38 ubuntu kernel: [   12.423300] e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
Aug 26 05:54:38 ubuntu kernel: [   12.436023] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
Aug 26 05:55:05 ubuntu kernel: [   39.322268] audit_printk_skb: 150 callbacks suppressed
Aug 26 05:55:05 ubuntu kernel: [   39.322272] audit: type=1400 audit(1535288105.459:62): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/lib/cups/backend/cups-pdf" pid=2171 comm="apparmor_parser"
Aug 26 05:55:05 ubuntu kernel: [   39.322282] audit: type=1400 audit(1535288105.459:63): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2171 comm="apparmor_parser"
Aug 26 05:55:05 ubuntu kernel: [   39.322809] audit: type=1400 audit(1535288105.459:64): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2171 comm="apparmor_parser"
Aug 26 06:15:14 ubuntu kernel: [ 1248.118385] hello: module verification failed: signature and/or required key missing - tainting kernel
Aug 26 06:15:14 ubuntu kernel: [ 1248.121354] Hello kernel, it's 2014!
Aug 26 06:16:13 ubuntu kernel: [ 1306.921227] Bye, kernel!
root@ubuntu:~/Desktop#

出现的问题
1.用 ide 可能报找不到#include <linux/kernel.h> 等头文件
确实 include里面没有
这个没关系因为有内核源码先查看内核版本

root@ubuntu:~/Desktop# uname -r
4.2.0-27-generic
root@ubuntu:~/Desktop#

再写 makefile 文件时用$(shell uname -r) 就可以了

linux 驱动开发

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