On Thu, Mar 20, 2008 at 12:03:37PM -0400, Arun Hegde wrote:
> Hi,
> 
> I am working on WLAN driver which follows io-net framework. I have an application, which looks as follows:
> 
> 
> struct mystruct{
> int count;
> char *data;
> };
> uint8_t buf[SCAN_MAX_DATA];
> 
> struct mystruct var;
> var.data = buf;
> 
> and i am calling devctl as follows.
> 
> if(devctl(fd,cmd,&var,sizeof(var),NULL) >= 0)
>  {
> }
> 
> 
> I am filling up this data( var. data which is pointing to buf in application) in my driver. But in my appliction when 
i read the buffer i am not able get the data which is filled by the driver.
> My doubt is as both application and driver runs as separate processes, the buf from the application is not being 
copied to derivers process space. 
> How do i get the correct datain application which is modified by my driver?

That's the problem exactly.  You can't pass pointers
between processes (io-net isn't a monolithic kernel).
Change mystruct to:

struct mystruct{
int count;
char data[SCAN_MAX_DATA];
};

-seanb