In message 431DD0C1.6040707@smiths-aerospace.com you wrote:
U-boot typically runs with instruction cache enabled and data cache disabled (experience base: PowerPC). This is because instruction cache
We typically enable icache, that's true. If data cache is on or off depends, even on PowerPC. See the README.
"just works" and is very beneficial and data cache generally causes massive grief (it is pretty much useless without setting up the BATs or full MMU on the PowerPC).
Data cache can be very important if you need an initial stack before you have any writable memory on the system.
It sounds like Robin has data caching turned on, which would explain why he needs to flush the data cache before jumping to his newly loaded
No, it does not. As I just explained, all download commands implement cache flushing (I think).
Best regards,
Wolfgang Denk