I checked in some openfirmware changes to fix the lxdevel build.
The lxdevel build is now independent of the files in cpu/x86/pc/olpc ; everything that it used to include from that directory has either been moved out (to cpu/x86/pc and dev/geode as appropriate), or copied into cpu/x86/pc/lxdevel and modified as necessary, or deleted from the load files.
I've tested the changes to the following extent:
a) Built the OLPC version and tested the result on an OLPC machine
b) Built the lxdevel version - it compiles cleanly - but did not try it on actual hardware
There is a residual OLPC dependency in the nand5536 driver, which includes a couple of files from dev/olpc/cafenand/ . I doubt that will be a problem in practice.