using /dev/mem to talk to peripherals on VIIP system

[Dan Malek]

On Jul 28, 2006, at 1:35 PM, scott wrote:

>   ptr = MAP_FAILED; // Initialize to bad value
>   ptr = (int *) mmap(0, 256, PROT_READ|PROT_WRITE, MAP_SHARED, fd,  
> USER_LOGIC_BASEADDR);

Well, this isn't going to detect an error, since the error code
is returned instead of an address.

>
>   if(ptr==MAP_FAILED) {

        if ((int)ptr == -1) {
>     printf("Err: cannot access address!\n");
>     return -1;
>   }
>

> ....  Any other thoughts?

Your mmap is failing because the size is not modulo PAGE_SIZE.


        -- Dan