Re: [tlug] Just curious... how much impact does a kernel update make?

["Stephen J. Turnbull" <stephen@example.com>]

Ian Wells writes:

 > True-ish, but there have been directory reorgs within 2.6 and speaking
 > from personal experience I can say that modules compilable and
 > runnable for one 2.6.x don't always compile or run on 2.6.y - so is
 > this 'significant'?

It is to you! ;-) I know a lot of the module writers complain about
that.

 > What I would wish for (I won't predict, since I'm not convinced
 > that kernel hackers themselves know what they're going to do from
 > one day to the next) is a kernel that is a lot smaller than the
 > current kernel.

What's wrong with NetBSD? ;-)

 > There's risk in complexity, and the kernel has never shrunk between
 > versions.  It would make a lot of sense to try and reduce
 > complexity, in my opinion, even if this does break compatibility.

Well, in some ways the kernel *is* simpler today than it once was.
It's better-factored, and many of the accreted optimizations, while
they increase the amount of code, have been exhaustively analyzed and
been stable for years.  The amount of code present does not
necessarily correspond exactly to total complexity.

 > > amusing) suggests that it is *very* unlikely that POSIX has the tools
 > > to handle it, and Linux really is a very POSIX system.
 > 
 > POSIX-and-only-POSIX compatibility isn't something that's held people
 > back in the past.  Linux has non-POSIX stuff in any number of areas, I
 > don't see why one more would be a concern.

Just because it's not listed in POSIX wouldn't be a concern; I'm
suggesting that this one could be backward incompatible enough (eg,
suppose the locking protocol adopted requires old programs not
participating in the new features to respect it too, changing the
semantics of eg I/O in those programs even though they haven't changed
their code?) to warrant a major version bump.