[ltp] Active Protection System

[Richard Neill]

Alejandro Bonilla Beeche wrote:
  > 	The code included in head_park actually works for most HD that have the
> correct firmware and that quite actually work with HDAPS in Windows.
> Yes, we need to add a timeout for the code at least right now that parks
> the head for a certain amount of time. This is at the moment the key
> that is holding us back. We already found a nice way to actually make a
> daemon know when it should kick in. I'm still static in thinking that I
> should add some laptop_mode features when we encounter soft movement on
> the laptop. It will not park the head with soft movement, but will only
> launch laptop_mode and then make things run in buffer and so... If
> heavier movement is found, then we apply the head_park that should be
> fixed. I will ask LKML now.

I've tried this in Windows - by default, the system is so sensitive that 
the laptop cannot be used in a car. This means that many users will just 
disable it.

A way to work around this might be to store the average amplitude over 
the last 5 seconds. Then, if we are already vibrating, turn down the 
sensitivity a bit. But if we are on a flat surface, such as a table top, 
we can have the maximum sensitivity and protection.

Another idea: in some situations, could be a useful anti-theft device. 
Eg if the machine is:
	* on a flat surface (and has been for a minute or two)
	* has not had any user input for, say 30 seconds
	* is suddenly moved
then (optionally)
	* lock the screen
	* beep beep beep (getting louder):
	* play a wav file: "Help! I'm  being stolen"
	* pop up a dialog box requiring a password within 1 minute, or
	  shut down the machine. This will unmount any encrypted
	   filesystems.

Of course, this is NOT a serious mitigation against most risks. But it 
might be a nice feature and would be useful in some cases, (eg preparing 
for presentation, want to take eye off laptop for a moment)



Regards

Richard