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Date: Tue, 22 May 2001 17:34:14 -0700 (PDT)
From: SJ <sandejain@rocketmail.com>
Subject: Device driver questions
To: freebsd-questions@freebsd.org
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Hi all,
I am new to writing device drivers...so please excuse
my ignorance.

I have a couple of questions regarding that:

1. "ioconf.c" contains struct config_resource and
    config_device definitions for declarations in 
    "config" file. But I noticed that for some devices
     e.g. device          atadisk
          device          atapicd
          ...
     the corresponding lines in ioconf.c are missing??
      

2. Whats the use of device_ops structure and what does
   "ops" stand for?

3. File naming question:
   whats the reasoning behind having "bus.h" and 
   "bus_private.h"....whats the significance of 
   "private" here.

4. concept behind having devclasses...I know that   
   devclasses for a particular bus holds devices and
   device drivers for that bus. But then whats the  
   need for defining a devclass for each driver we 
   write ?

5. Any poniters to literature which explains the 
   design philosophy and code specific help for device

   drivers in freebsd - I am referring to files 
   kern/subr_bus.c, bus.h, bus_private.h, isa/* etc.
     
thanks for your help,
SJ

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