Jaromir Dolecek <jdolecek@netbsd.org> writes:

> FWIW, bits like fsck, ifconfig and even ps don't break when you
> have older userland then kernel.

Sure they do.  1.6 fsck checks too many bits and requires they be
zero.  A -current kernel sets those bits, so after mounting read/write
the fs will not fsck cleanly.

> Err, actually, NetBSD backward compatibility is very good, coutrary
> to that of Linux or FreeBSD.

I ran a 1.6 userland with a -current kernel (and a statically linked
fsck_ffs, see above) for a very long time.  I know someone who tried
to update their linux system and had to update a whole list of things
to make it work right.  That said, more kernel modules would be nice,
even if they do have to be version specific.

It would almost be nice to have a kernel version that was internal API
specific, and one that is "external API" specific.  That way loadable
modules can track the internal one, but ps, netstat, etc. can parse
the external one.  I know, not worth the bother.

--Michael