how to write your first linux device driver

how to write your first linux device driver

0. environment
-ubuntu 1804 64bit

1. apt-get install linux-headers-$(uname -r)

2. code hello.c

#include <linux/init.h>

#include <linux/module.h>

MODULE_LICENSE("Dual BSD/GPL");

static int hello_init(void)

{

printk(KERN_ALERT "Hello, solidmango\n");

return ;

}

static void hello_exit(void)

{

printk(KERN_ALERT "Goodbye, solidmango\n");

}

module_init(hello_init);

module_exit(hello_exit);

3. Makefile

# If KERNELRELEASE is defined, we've been invoked from the

# kernel build system and can use its language.

ifneq ($(KERNELRELEASE),)

obj-m := hello.o

# Otherwise we were called directly from the command

# line; invoke the kernel build system.

else

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

PWD := $(shell pwd)

default:

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

endif

4. sudo insmod hello.ko

5. sudo rmmod hello

6. view result

sm@ubuntu:~/dev$ cat /var/log/syslog|grep solidmango

Sep  :: ubuntu kernel: [ 3041.143749] Hello, solidmango

Sep  :: ubuntu kernel: [ 3068.192172] Goodbye, solidmango

7. sign your kernel module

/lib/modules/4.15./build/scripts/sign-file sha512 /lib/modules/4.15./build/certs/signing_key.pem /lib/modules/4.15./build/certs/signing_key.x509 hello.ko

signing_key.pem and signing_key.x509 files are generated when build the linux kernel

reference
https://wiki.gentoo.org/wiki/Signed_kernel_module_support#Enabling_module_signature_verification

巴特西

how to write your first linux device driver

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