Hi guys

I am learning embedded linux, and I was looking at this schematic here: http://www.acmesystems.it/schematics/schematic_arietta.pdf.

Who is responsible to figure out how much external ram is connected to the processor:

• the first boot program in the rom of the MPU?
• bootstrap code (second boot loader) stored in the external storage (flash, sdcard etc)?
• bootloader/third bootloader (eg u-boot)?

Thanks guys!

 

I think I found the answer myself, bootstrap(second level loader) is responsible for initializing the external RAM.
ref: http://www.at91.com/linux4sam/bin/view/Linux4SAM/GettingStarted#Boot_sequence

That lead to another question:

Do I need to recompile the bootstrap if the external ram is replaced with a bigger size one? (eg replace 16MB to 32MB)

 

For anyone with the same question, I think the answer is here:

http://www.acmesystems.it/compile_at91bootstrap