against 2.2.18pre21
As usual, since all 2.4.0-test* kernels set LINUX_VERSION_CODE to the same
value, if you are running a 2.4.0-test kernel, you MUST be running
2.4.0-test11-pre4 or later (although anything after 2.4.0-test11-pre1
should work fine -- I tested with pre4/pre5). I expect 2.2.x support to
continue to work for all recent kernels, but I tested with 2.2.18pre21
-- we use the old intermodule symbol communication for 2.2.x kernels,
so they should all continue to work.