"Mike A. Harris" <mharris@meteng.on.ca> said:
> On Sun, 23 Jul 2000, Paul Barton-Davis wrote:
[...]
> >Right now, you can write (for example) an Iomega Jaz utility without
> >any kernel futzing at all. Contrast this with Windows where it seems
> >necessary to always install a new driver.
> >
> >Don't go there.
> Part of the kernel's JOB is to arbitrate hardware access. If we
> extend your argument, we take out all hardware drivers and
> replace them with userland applications and libraries. Then we
> end up with MSDOS.
It is the kernel's responsibility to place a layer of code on hardware that
makes it easy and hopefully safe to use; within (softish) restrictions
given by convenience, size, and complexity; considering in-kernel
development effort vs effort and costs of other alternatives. So, handling
a block device of some sort in an uniform way is definitely in (it is a
task done hundreds of times a second), handling dozens of undocumented ways
of reconfiguring said device isn't necessarily in (it is perhaps done once
or twice during the lifetime of the machine, if ever). Here it is much more
efficient in kernel (and overall) developer time to just leave that task to
a specialized userland program (which can and will be adjusted as needed
whenever the raw interface changes, or is just fed the latest version of
the firmware straight from the provider's FTP site), and protect access to
the raw facility for doing same in some generic way.
The kernel is _not_ responsible for "fixing" broken hardware design. If it
can work around the brokeness with little cost, or if it is critical to the
system's second to second job, so be it. Else, forget about placing it in
the kernel.
Remember this isn't a "Theory of Operating System Principles" example, this
is a real-world operating system (and a large software project with a
distributed developer base).
-- Dr. Horst H. von Brand mailto:vonbrand@inf.utfsm.cl Departamento de Informatica Fono: +56 32 654431 Universidad Tecnica Federico Santa Maria +56 32 654239 Casilla 110-V, Valparaiso, Chile Fax: +56 32 797513- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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