[ILUG-BOM] I/O ports access for normal users?

[Tahir Hashmi]

On Fri, 18 Jan 2002 18:20:18  
 Rahul Saxena wrote:
>hi everyone, 
>
>I was tryign to read/write bits to 0x378 I/O port,
>using the ioperm() system call.
>But this allows only the root to access. 

I think you should explore better ways than directly allowing the users to access the port, like writing a device driver module. Not that I've ever done that, but I have this wariness for allowing users to access the hardware directly. That was the DOS way of doing it, right?

>
>HOw do normal users access the port? 
>i did read about SETUID(), but i dont really
>understand how it works for me ?? 

# chown root:root <filename>
# chmod a+sx <filename>
>
>does anyone have any pointers on this ?? 
>
>Also i am trying to uderstand how ot access using read
>and write. for that i would need to add the user as
>part of the group, which can access /dev/port. 
>
>How do i add myself to the group? i guess.. in that
>case i wont be in my original group. 
>

I really think it would be best if you do it the accepted way (I consiously avoided the word "right" :-). Normal users aren't supposed to be accessing I/O ports directly. Try going thru _Linux Device Drivers_ by O'Rilley Publications for enlightenment.

>
>Thanks for reading 
>
>-rahul 
>

--
Tahir Hashmi (VSE, NCST)
http://tahirhashmi.scriptmania.com
mailme at tahirhashmi.scriptmania.com

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