Bernie, thank you - everything you said is quite helpful.
None of the Fedora kernel packages comes close to the OLPC kernel. It's a completely independent codebase, forked off from Fedora some 3 years ago.
Despite this separate fork, I'm still pondering -
* Which kernel.org version of 2.6.31 (i.e., 2.6.31.??) was harvested for 2.6.31_xo1-20100823.1641.1.olpc.12d64069981699a ?
* Am I wrong in thinking that modules in 2.6.31../kernel/drivers/usb are unlikely to have been patched for the OLPC ? If they haven't, then I should be able to get that Fedora source instead of forked.
Thanks, mikus