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Re: [ts-7000] TS7200 Accessing LEDs - Why must I use mmap()?

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Subject: Re: [ts-7000] TS7200 Accessing LEDs - Why must I use mmap()?
From: Kevin Cozens <>
Date: Fri, 07 Jan 2011 02:01:48 -0500
frank_kienast wrote:
> Maybe I'm doing something stupid here, but it seems like I have to use
> mmap() to access the LEDs on the TS7200.

Its part of the separation between user space and kernel space in the
system. User programs run in virtual memory space. Pointers to memory are
pointers to virtual addresses. To gain access to the real memory location 
you have to ask for a pointer that will map to the real physical address.

Accesses to real memory and/or memory addresses used by physical devices is 
usually restricted to kernel drivers or programs running with root 
permissions. You don't want just anyone to be able to poke around in the 
real memory and potentially get access to any security certificates or 
passwords.

You can read a bit more about mmap at http://en.wikipedia.org/wiki/Mmap



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