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Detailed boot process LS1021a SD-card-boot and NOR-boot

Question asked by Jan Brand on Jul 12, 2016
Latest reply on Jul 15, 2016 by Serguei Podiatchev


I've got a ls1021atwr here. I'm a bit confused about the booting process in ls1021a, before U-Boot Startup. I guess a  boot from NOR differs much more from SD-Boot than i thought - or not. Maybe you can help me to understand the startup...

Please correct me if i'm wrong:

A startup with SD-Boot looks like the following:

1. Power

2. Pre-Boot-Loader get's the cfg_rcw_src to SD-Boot

3. Pre-Boot-Loader load the RCW with Preamble from SD-Card AND the U-Boot SPL into internal RAM

4. The Code in the internal RAM is executed

5. This Code initialize the external RAM...

6. ...And loads the U-Boot into it.

7. The U-Boot Code in the ext. RAM is executed and all is fine.


And now i stock on NOR-Boot:

1. Power

2. Pre-Boot-Loader get's the cfg_rcw_src to NOR- Boot

3. Pre-Boot-Loader loads the RCW binary from a fixed (where defined?) Adress in NOR. (Why can the PBL already read a NOR-Flash - is there no need to load a driver or whatelse?)

4. Pre-Boot-Loader loads directly the U-Boot without SPL into the external RAM

5. This Code in the external RAM and all is fine.