Porting non-mmu code to MMU -- MMU memcpy SEGV

I REALY AM STUMPPED... Any help would be GREATLY APPRECIATED!!

I added the following to mmap to my device driver:

static int my_mmap(struct file * filp, struct vm_area_struct * vma)

{

int ret;

printk( KERN_DEBUG "IN MYDRIVER MMAP\n");

long length = vma->vm_end - vma->vm_start;

printk(KERN_DEBUG "length %d PageSize %d [%d]\n", length , PAGE_SIZE, MY_NPAGES*PAGE_SIZE);

/* check length - do not allow larger mappings than the number of

pages allocated */

if (length > MY_NPAGES * PAGE_SIZE)

return -EIO;

printk(KERN_DEBUG "before remap_pfn_range\n" );

/* map the whole physically contiguous area in one piece */

if ((ret = remap_pfn_range(vma,

vma->vm_start,

virt_to_phys((void *)kmalloc_area) >> PAGE_SHIFT,

length,

vma->vm_page_prot)) < 0) {

printk(KERN_DEBUG "ret %l [%l]\n", ret);

return ret;

}

printk(KERN_DEBUG "return 0\n" );

return 0;

}

GLOBALLY I HAVE:

static int *kmalloc_area;

// original pointer for kmalloc'd area as returned by kmalloc

static void *kmalloc_ptr;

# define MY_NPAGES 16 /// 100

In the init of the device driver I have:

/* allocate a memory area with kmalloc. Will be rounded up to a page boundary */

if ((kmalloc_ptr = kmalloc((MY_NPAGES + 2) * PAGE_SIZE, GFP_KERNEL)) == NULL) {

ret = -ENOMEM;

goto out;

}

/* round it up to the page bondary */

kmalloc_area = (int *)((((unsigned long)kmalloc_ptr) + PAGE_SIZE - 1) & PAGE_MASK);

strcpy(kmalloc_area,"scmd_mmap test data");

for (i = 0; i < (MY_NPAGES * PAGE_SIZE / sizeof(int)); i += 2) {

kmalloc_area[i] = (0xdead << 16) + i;

kmalloc_area[i + 1] = (0xbeef << 16) + i;

}

AND IN USER SPACE I DO THE FOLLOWING:

# define DevName "/dev/myDriver0"

static unsigned int * mmapResult;

if ((fdPlayback = open("/dev/myDriver0", O_RDWR | O_NONBLOCK | O_SYNC)) < 0) {

perror("DevNameIO");

printf("error opening device %s\n", DevName);

return -1;

}

mmapResult = (unsigned int *)mmap (0, MY_NPAGES*PAGE_SIZE, PROT_WRITE | PROT_READ , MAP_SHARED | MAP_FILE | MAP_FIXED , fdPlayback, 0 );

///////// printf("AFTER -- mmap call [%d] MAP_FAILED {%d}\n", mmapResult, MAP_FAILED);

printf("userspace waiting ---- \n");

usleep(5000000);

if ( mmapResult == (unsigned int *)MAP_FAILED )

{

printf("mmap error for output\n");

perror("BOH");

return -1;

}

When I run my tstMmu program I get:

Open dev_is_open 1 INODE major 240 minor 0

IN PB9X-MMAP

length 65536 PageSize 4096 [65536]

before remap_pfn_range

return 0

CLOSING--> dev_is_open 0 INODE major 240 minor 0

SEGV

*****************************************************************************************

SO -- what is NOT HAPPY? The close of the device driver gets executed before the SEGV

Do I need something else to use the memory? I read an example where they have to do a 'mknod node c driverMajor# 0' and they opened up "node." I haven't tried this but if that is what I need to do is there somewhere I can read to explain this for me?