Re: A Layered Kernel: Proposal

[Christer Weinigel <christer@weinigel.se>]

Grigor Gatchev <grigor@zadnik.org> writes:

> > In the linux kernel I think that one of the most important things I've
> > learned from it: middle layers are usually wrong.  Instead of hiding a
> > device driver behind a middle layer, expose the low level device
> > driver, but give it a library of common functions to build upon.  That
> > way the driver is in control all the time and can use all the neat
> > features of the hardware if it wants to, but for all the common tasks
> > that have to be done, hand them over to the library.
> 
> By principle, the "least common denominator" type container layers are
> bad, because of not being extendable; you are completely right here. A
> class-like driver object model seems better to me. And the class-like
> model is not the only one that is nicely extendable. 

> You seem to be knowledgeable on the topic - what driver object model
> would you suggest for a driver layer model?

Thanks for the confidence, bur I really don't know, it's much easier
to criticize someone elses design than to come up with a good one
myself. :-)

With that said, I think that they way the Linux kernel is moving
regarding to IDE/SCSI devices is a good idea.  Linux has been around
for a while now and the Linux people have tried lots of things that
turned out not to be such a good idea after all.  Many things are
still there in the kernel, but if it's important enough, it gets
cleaned up after a while.

  /Christer

-- 
"Just how much can I get away with and still go to heaven?"

Freelance consultant specializing in device driver programming for Linux 
Christer Weinigel <christer@weinigel.se>  http://www.weinigel.se