Compiling a newer module on an older kernel. Possible, limitations ?

[Jasper <rjnoe@xs4all.nl>]

Hello list, I frequent a forum that deals with the "Acer Aspire One", a
mini-laptop that is sold with "Linpus Linux" installed, a specialised
distribution based on Fedora.

Now there are many brand new Linux users who want their "3G" highspeed
wireless usb dongles to work. In many cases that is possible, but there
are also cases where a module needs to be compiled or even a kernel
upgraded. But these new users are not ready to do that.

Afaik it is possible to compile modules for one machine on another
machine, with the source for the target-kernel available. Then we can
say: "put this module in /lib/modules/..etc.. and run depmod"

Now my question is: what happens if I take the source of a module that
is part of the latest kernel ( say 2.6.26-rc5 ) and compile that with
the source of the target-kernel ( 2.6.23.9 ).

Is that possible, good, wrong or what ?

I ask, because I cannot test it and want to be sure I do the right
thing.

Thanks, --Jasper.