U-boot typically runs with instruction cache enabled and data cache disabled (experience base: PowerPC). This is because instruction cache "just works" and is very beneficial and data cache generally causes massive grief

This is how we have things set up (data cache and instruction cache on by default).

Based on the fact that uncompressing an image :

icache dcache time boot* off off 11 seconds off on 10 seconds on off 3 seconds on on 1 second

*time to boot is based on the time to bootm to check the checksum, and uncompress the image, and print out "Starting Kernel at 0xnnnnnn".

Our customers want sub 2 second boot time - so we need to have both dcache and icache on.

If the restriction is that you can't use the go command with dcache on, then I can also live with that (and just put 'dcache on;' as part of the boot command for Linux kernels.

-Robin