Hi,
How about amending the U-Boot design principles with
Go for it - it's a wiki.
Thinking about it, I turned it not into a rule, but into a Lemma from the 10 rules:
Lemmas from the golden rules
1. Generic Code is Good Code
New code shall be as generic as possible and added to the U-Boot abstraction hierarchy as high as possible. As few code as possible shall be added in board directories as people usually do not expect re-usable code there. Thus peripheral drivers should be put below "drivers" even if they start out supporting only one specific configuration. Note that it is not a requirement for such a first instance to be generic as genericity generally cannot be extrapolated from a single data point.
Feel free to amend / modify that.
Cheers Detlev
[1] http://www.denx.de/wiki/rdiff/U-Boot/DesignPrinciples?rev1=1.14&rev2=1.1...
PS: Ok, actually I didn't want to ruin the magic 10 ;)