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Some thoughts about hardware persistency (e.g. video-card)

So, how to reinitialize a specific hardware?
- during booting and restoring the TV-app, before running the
process the hardware must be in the same state as before
- the initialisation must be in the same order than last init

• wether the driver or the application must be derived from a special class with an funtion executed once per boot
• these function uses a stack of stored function calls with parameters and executes them in order of first call
• the state of the application and the driver must be consistent (e.g. radio-mode vs. TV-mode)
• If the application wants to switch state it must rewind the stack and going all the way in the new state
• there are 2 classes of init-functions:
  1. to be executed in order, last one ending in a state (radio or tv-mode)
  2. can be exectued all time for a certain state ( radio vs. tv-mode ) (volume in both states, brightness only in tv-mode)

This leads to a initialisation-tree of function calls with functions and parameter sets as preconditions of other function calls. This structure should be as short as possible to minimize the number of possible combinations.
The reinit, preconditions, stack-functions, checking and state-keeping should be done by a base class, from which special classes are derived.

If EROS is burned in the mainboards flash chip, it might be possible to use these principle for the boot process too. (But here some very informations must be calculated from the CMOS contents...)

But it must be taken care for disallowing instable states going into a checkpoint. For the very worst case, we might need a save-boot without automatic reinit of certain hardware - is there something like a "rescue-system" for EROS required?

reset-state (might be undefined)
|
Chip-1 (Register A,B,C,...)
|

Chip-2 (Register A,B,C,...) ---- Chip-2 (Register A,B,C,...)		 <-x
|				 |					   |
Chip-2 (Register D,E,F,...)	 Chip-2 (Register D,E,F,...)		   |
|				 |					   | rewind
Chip-3 (Register A,B,C,...)	 Chip-4 (Register A,B,C,...)		   | the
|				 |					   | stack
Radio-Mode --- (CHIP 2,3 R...)   TV-Mode --- (CHIP 2,3,4 R...)		   |
				 |					   |
				 current-state				 --+

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