Changes to usb/serial: how to distinguish between old and new interfaces in 8-STABLE and 9-CURRENT branches?

[Lev Serebryakov]

Hello, Freebsd-usb.

  I'm author of `comms/umcs7840' port, which is module for usbcom,
like `uftdi' and `uplcom' in base system.

  Last changes, committed to 8-STABLE (and, earlier to HEAD), breaks
some API/ABI for such modules.

 I have tow questions:

 (1) How could I detect which version have user at compile time? I
don't use any autoconf/automake framework, my build framework is baed
on FreeBSD-native bsd.*.mk framework, so I need some define or
something like this to distinguish these versions. I could not find
anything suitable in revision 221612 commit.

 (2) WHY, OR WHY old module was loaded without problems?! ABI is
 broken (ucom_detach()? size of struct ucom_softc) and old module
 should complain on load, IMHO! Users will be very surprised when
 computer will reboot after system update!

-- 
// Black Lion AKA Lev Serebryakov <lev at FreeBSD.org>