linux-mips-fnet
[Top] [All Lists]

Re: Device Drivers

To: linux-mips@fnet.fr
Subject: Re: Device Drivers
From: Steven Lembark <lembark@wrkhors.com>
Date: Sun, 20 Dec 1998 12:16:53 -0600
Organization: Workhorse Computing
References: <Pine.LNX.3.96.981220110819.7799B-100000@apt4g.a3nyc.com>
Sender: lembark@wrkhors.com
T
> > The same problem as with much other good ideas: Seems to be a good idea, but
> > someone has to do it. And I'm quite sure that a hand-written driver will
> > offer much better performance if the programmer writing it knows what he's
> > doing.
> 
> This is sort of the same argument that was is about compilers versus
> writing in straight assembly language.  The compilers seems to have won
> out.

almost.  in some situations (e.g., interplanetary space
craft) you're still stuck with assy language.  there's also 
the problem of how to write the CASE tool.  compilers didn't
win out until they could generate reasonably optimized code,
vs. code that simply worked.  CPU speed also had a lot to do
with it: as the CPU speeds moved above Dhz the level of 
optimization required to get a job done decreased.  a 500MHz
machine can easily spend 50% of its time spinning on devices.
q.e.d., wasting a few cycles on "non-optimal" code won't hurt.

looking at the state of today's CASE tools they don't come 
close to generating the code a skilled programmer can if 
both work in the same language -- assy, C, whatever.  when
the CASE tool can generate code nearly equal to a programmers 
people will begin to switch.

another problem in using CASE for device drivers is that each
device -- a specific model of a specific piece of hardware from
a particular vendor at a particular time -- has its own foibles.
i've seen different specimens of the "same" hardware from different
manufacturing plants behave differently at the same rev level,
let alone different rev levels of the "same" part.

the SCSI "standard" is supposedly uniform but vendors have
implemented their own quirks.  result is that you can usually start
with someone else device driver but will probably have to tailor
it to the  specific machinery.  the CASE tool for generic
interfaces would have to be updated for the quirks in each device
that every vendor comes up with, which pretty much amounts to just
writing the  drivers.

-- 
 Steven Lembark                                   2930 W. Palmer St.
 Workhorse Computing                             Chicago, IL  60647
 lembark@wrkhors.com                                   800-762-1582
---------------------------------------------------------------------
  The opinions expressed here are those of this company.
  I am the company.
---------------------------------------------------------------------

Attachment: smime.p7s
Description: S/MIME Cryptographic Signature

<Prev in Thread] Current Thread [Next in Thread>