Subject: Re: Time to fix a 25 year old misdesign
To: NetBSD Kernel Technical Discussion List <tech-kern@NetBSD.ORG>
From: Lennart Augustsson <>
List: tech-kern
Date: 10/15/2000 20:17:21
"Greg A. Woods" wrote:

> > This could be fixed by introducing a device method that is called when
> > the reference count is increased (e.g. by fork).  But now its starts to
> > get unelegant...
> Indeed!  :-)
> There's also really no need either since with a correct driver design
> that separates functionality out logically to separate /dev files
> (i.e. with different minor numbers) will eliminate the need for such
> uglyness in the driver.

OK, so what about SIGIO?  (See my previous posting.)

> Changing this very fundamental part of the Unix I/O system design would
> have potentially far reaching implications that could "break" many more
> things than it is intended to fix (thus the elegance of the current
> design).

There is a certain elegance in the current design, but it also stops you
from doing things that you'd like to do.
I still think a design with a symmetry between "generate a driver reference"
and "drop a driver reference" would be more elegant.
Symmetry is beauty. :)


        -- Lennart