We've been working at adding support for i.MX233 in mainline U-Boot without using imx-bootlets. So far we have a great success adding basic support for it.
Currently I've been working at mxsboot tool to generate a binary blob capable of being directly put into SD/MMC and work.
In i.MX28 we use MBR and put a Boot Control Block (BCB) Data Structure in the first block of firmware partition however this does not seem to work. Checking i.MX23 datasheet it does not say anything about it support or not the BCB header.
Could someone confirm to me if BCB header is supported in MBR for i.MX23?