[U-Boot] Limitations/Considerations when programming U-Boot

["Oliver Stäbler" <oliver.staebler@bytesatwork.ch>]

Hi all,

I'm currently investigating the possibility of using a cryptographic 
library in U-Boot to verify signatures during a fatload (or similar).

So my question is, what has to be considered when choosing a crypto library?

As far as I understood so far, U-Boot only implements a part of the C 
Standard Library. So this has to be considered, right?

The README mentions that the stack space is very limited. Is this still 
the case when the "shell" is loaded or is this just the case during
initialization?
If so, this means for a crypto library that it should not do a lot in 
the stack, but prefer heap space?
Then again, are there any boundaries in using heap? Maybe increase 
CONFIG_SYS_MALLOC_LEN?

Is there anything else I have to consider?

Thanks,
Oliver