Does the scatter loading file mechanism have some method of adding a checksum to a rom region? And, most of all, if this exist: Can the checksum be reproduced by the target? Doing this manually for each release firmware is possible, but not preferred.
There is the ElfDwt tool, but I cannot find the method used to create the checksum. And this only seems to apply to the vector table to have NXP bootloaders accept the code.
I'd like to continuously check the startup file .o integrity and a one time boot .ANY ROM check. This since the product is placed in some hotter environments, which can cause issues.
However, for my application I would have to link twice. I'll second the question: why on earth do you think that you have to do that?
Maybe I need to look at a custom programming algoritm. Same here: why?
Maybe what you really need to do is take several steps back from the frontier of your problem and tell us what exactly it is you're doing. You're seeing problems that, IIRC, nobody else on this forum ever mentioned. So you must be doing something very differently from everybody else. Maybe you took a wrong turn several steps back, or seriously misunderstood some requirement even before that.