mmap

study/kernel/memory/mmap/mmap_test.c

@@ -42,10 +42,7 @@ static int my_map(struct file *filp, struct vm_area_struct *vma)
     unsigned char i;
 
     unsigned long start = (unsigned long)vma->vm_start;
-
-
-    //unsigned long end =  (unsigned long)vma->vm_end;
-
+    unsigned long end =  (unsigned long)vma->vm_end;
     unsigned long size = (unsigned long)(vma->vm_end - vma->vm_start);
 
 
@@ -60,7 +57,6 @@ static int my_map(struct file *filp, struct vm_area_struct *vma)
 
 
     //往该内存写10字节数据
-
     for(i=0;i<10;i++)
     {
         buffer[i] = array[i];
@@ -102,6 +98,8 @@ static ssize_t hwrng_attr_current_show(struct device *dev,
 static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
                    hwrng_attr_current_show,
                               NULL);
+
+
 static int __init dev_init(void)
 {
     int ret;

study/kernel/memory/mmap/test.c

@@ -1,45 +1,57 @@
-#include <unistd.h>  
-#include <stdio.h>  
-#include <stdlib.h>  
-#include <string.h>  
-#include <fcntl.h>  
-#include <linux/fb.h>  
-#include <sys/mman.h>  
-#include <sys/ioctl.h>   
-  
-#define PAGE_SIZE 4096  
-  
-  
-int main(int argc , char *argv[])  
-{  
-            int fd;  
-                int i;  
-                    unsigned char *p_map;  
-                          
-                        //打开设备  
-                        fd = open("/dev/mymap",O_RDWR);  
-                            if(fd < 0)  
-                                        {  
-                                                        printf("open fail\n");  
-                                                                exit(1);  
-                                                                    }  
-  
-                                //内存映射  
-                                p_map = (unsigned char *)mmap(0, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED,fd, 0);  
-                                    if(p_map == MAP_FAILED)  
-                                                {  
-                                                                printf("mmap fail\n");  
-                                                                        goto here;  
-                                                                            }  
-  
-                                        //打印映射后的内存中的前10个字节内容  
-                                        for(i=0;i<10;i++){  
-                                                        printf("%d\n",p_map[i]);  
-                                            p_map[i] = i + 10;  
-                                        }  
-                                              
-  
-here:  
-                                            munmap(p_map, PAGE_SIZE);  
-                                                return 0;  
-}  
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <linux/fb.h>
+#include <sys/mman.h>
+#include <sys/ioctl.h>
+
+#define PAGE_SIZE 4096
+
+
+int main(int argc , char *argv[])
+{
+
+    int fd;
+    int i;
+    unsigned char *p_map;
+
+
+    //打开设备
+    fd = open("/dev/mymap",O_RDWR);
+
+    if(fd < 0)
+    {
+        printf("open fail\n");
+        exit(1);
+    }
+
+
+
+    //内存映射
+    p_map = (unsigned char *)mmap(0, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED,fd, 0);
+    if(p_map == MAP_FAILED)
+    {
+
+        printf("mmap fail\n");
+        goto here;
+    }
+
+
+
+    //打印映射后的内存中的前10个字节内容
+    for(i=0;i<10;i++)
+    {
+        printf("%d\n",p_map[i]);
+        p_map[i] = i + 10;
+    }
+
+
+
+
+here:
+
+    munmap(p_map, PAGE_SIZE);
+    return 0;
+}