Just a basic question about custom firmware on devices like the 5800.
I'm an embedded developer, so I understand the concepts of modding firmware or even building new distributions from scratch from the OS code. What I don't understand is what people are doing in THIS set of handset / firmware models.
I'm aware Symbian has gone open source with S^4 or whatever, but AFAIK the N8
is the first phone based on S^3 or S^4 (I don't recall which), and all the older ones line 5800 XM are based on much older OS code which you can't freely get.
So I assume that the "custom" does NOT mean that you start with open source Symbian S^4 OS code and compile a totally custom OS + apps for the handset to make it S^4 based, right? I mean even if the phone had the hardware specs. to do
that well (memory, flash, CPU speed), I assume that nobody has enough of the hardware specifications for the phone's chips / registers / driver needs / memory etc. to make it even POSSIBLE (practically) for an outsider to make a totally custom from scratch Symbian (or android or whatever) OS build for the 5800, right?
So the only other "custom" I can assume would be it is some kind of modified variant of an existing downloadable firmware package that was specifically intended originally for the 5800, and people just found ways to slightly modify it by adding/deleting apps, changing some basic settings, etc.? Is this what "custom" means for the 5800?
If so I can see the usefulness, but it seems like it is still far more limited than something that is truly "custom" as above.
What are the starting points of firmware / code / tools / documentation you'd use to make a "custom" 5800 or 53xx or 52xx firmware? What's the best place to go for information about learning how to make one or derive from an already available one?