Or perhaps get rid of that unworkable "version number" thing
(just freeze it in time with the 2.6.35 value returned),
and implement a "get_feature_flags" ioctl or something for going forward.
Then you can just turn on new bits in the flags as new features are added.

It's a kludge (to get around the poor use of -EINVAL everywhere),
but at least it's a design that's workable.

Cheers