Linux驱动开发之Linux内核空间内存分配

1、源代码文件

#include
#include
#include

static char *buf1 = NULL;
static char *buf2 = NULL;

static int __init alloc_mem_init(void)
{
int ret;

buf1 = kmalloc(100, GFP_KERNEL); // 在内核空间分配100个字节的内存
if(!buf1){
ret = -ENOMEM;
pr_err("allocate memory failed with kmalloc\n");
return ret;
}
memset(buf1, 0, 100); // 清空这100个字节的内存
strcpy(buf1, "--- kmalloc memory ok ---");// 把字符串拷贝到buf1中
printk(KERN_INFO "buf1 = %s\n", buf1);

buf2 = get_zeroed_page(GFP_KERNEL); // 分配一页内存并清空这一页内存
if(!buf2){
ret = -ENOMEM;
pr_err("allocate memory failed with get_zeroed_page\n");
return ret;
}
strcpy(buf2, "--- get zeroed page memory ok ---");// 把字符串拷贝到buf1中
printk(KERN_INFO "buf2 = %s\n", buf2);

printk(KERN_INFO "alloc_mem_init ok\n");

return 0;
}

static void __init alloc_mem_exit(void)
{
if(buf1){
kfree(buf1); // 释放分配的内存
buf1 = NULL;
}

if(buf2){
free_page(buf2); // 释放分配的一页内存
buf2 = NULL;
}

printk(KERN_INFO "alloc_mem_exit!\n");
}

MODULE_LICENSE("GPL v2");
MODULE_VERSION("v1.0");
MODULE_DESCRIPTION("Linux Kernel Memory Allocate Module");
MODULE_AUTHOR("David");
MODULE_ALIAS("Mermory Allocate Module");

module_init(alloc_mem_init);

module_exit(alloc_mem_exit);

2、Makefile

ifeq ($(KERNELRELEASE),)
KERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)
all:                               
        $(MAKE) -C $(KERNELDIR) M=$(PWD) modules
clean:                                             
        $(MAKE) -C $(KERNELDIR) M=$(PWD) clean
else
    obj-m := alloc_mem.o

endif

3、验证测试

1）make

2）sudo insmod alloc_mem.ko

3）dmesg

buf1 = --- kmalloc memory ok ---
buf2 = --- get zeroed page memory ok ---

alloc_mem_init ok

4）sudo rmmod alloc_mem

5）dmesg

alloc_mem_exit!