Kernel/Why do i get Unhandled fault: imprecise external abort?

[zozo1234]

I have this in kernel module:


/*global scope declared*/
static char array[10]={1,2,3,4,5,6,7,8,9,10};


and I have functions for open close read and write works perfectly, i want to share the `array[8]` with the user space application in the bottom of this page.

**in the kernel module:**


static int *my_mmap (struct file *filep, struct vm_area_struct *vma ) {

if (remap_pfn_range(vma,
vma->vm_start,
virt_to_phys(array)>> PAGE_SHIFT,
10,
vma->vm_page_prot) < 0) {
printk("remap_pfn_range failed\n");
return -EIO;
}


return 0;


**the application in user-space's source code:**


#define LEN (64*1024)
/* prototype for thread routine */

#define FILE_PATH "/dev/my_module"


int main()
{
int i=0;
int fd = open(FILE_PATH,O_RDWR);
int* vadr = mmap(0, LEN, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);

for (i=0;i<10;++i){

printf("%d",*(vadr+i));
}

return 0;
}



I get `imprecise external abort` and no output from vadr, why is that?

[Rubberman]

Please post code inside code blocks, like this:

/*global scope declared*/ 
static char array[10]={1,2,3,4,5,6,7,8,9,10};

static int *my_mmap (struct file *filep, struct vm_area_struct *vma )
{
     if (remap_pfn_range(vma, vma->vm_start, virt_to_phys(array)>> PAGE_SHIFT, 10, vma->vm_page_prot) < 0)
     {
         printk("remap_pfn_range failed\n");
         return -EIO;
     }
     return 0;
}

// the application in user-space's source code:**

#define LEN (64*1024)
/* prototype for thread routine */

#define FILE_PATH "/dev/my_module"


int main() 
{
     int i=0;
     int fd = open(FILE_PATH,O_RDWR);	
     int* vadr = mmap(0, LEN, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);

     for (i=0;i<10;++i)
     {
          printf("%d",*(vadr+i));
     }

     return 0;
}

It make it a lot easier to read. In any case, this is not sufficient to help you. Please post ALL of your kernel module code, and how you access it from your user-space code.

[zozo1234]

Thanks,

My question is, how do I share memory between a kernel module and user space even if the block of data is not aligned to a page size.
For example how do I share the

/*global scope declared*/ 
static char array[10]={1,2,3,4,5,6,7,8,9,10};

declared in a kernel module with a user application?

thanks