[ROM] functionalities in asm code

[baskaranindia]

Description

The rom_start.S asm file implements lot of functionalities (interrupt, reset, RMA, Power, watchdog, clock, memory init) in asm code. is there specific reasons for implementing them in asm ?

Can they be moved to C code ?

[jwnrt]

1. I think a lot of those (interrupts, resets, watchdog, etc.) just need to be initialised very early before we’ve had time to prepare an environment for C.

2. I believe we want the RMA loop to come before most other initialisation so that any fault in hardware won’t prevent us from RMAing a chip. Contrast with the bootstrap loop later on in C.

3. Memory initialisation is needed to support the C environment.

Do you have a particular concern about this ASM? It's not clear to me personally that much of what's in there would be safer / easier to review in C.