[En-Nut-Discussion] at91sam7x bloader

[Alain M.]

Szemző András escreveu:
> I save some RAM maybe, but I don't really know.

Anyway, you need the recording code in RAM, this is automatic in Nut/OS, 
but is taken care in IPL, so be carefull if you play around with more 
than one image.

> My exact problem is, what other steps needed before the jump :)

This is a suggestion of how I intend to implement it:

1) link your bootloader as an independant non-Nut program and place it 
at the end of flash space, Have a fixed entry.point.

2) Modify the main program's IPL so that as 0x4000 to allways jump to 
the bootloader, make a fixed re-entry point, probably something like 
0x4004 or 0x4008.

3) Every time the bootloader checks if there is something to do and 
jumps to the re-entry point.

This is probaly the implementation that has the least dependancies. The 
only thing that could go wrong is if the bootloader is deleted.

Alain