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From: jca@pnet01.cts.com (John C. Archambeau)
Newsgroups: comp.os.minix
Subject: Re: disk controllers
Message-ID: <5404@crash.cts.com>
Date: 2 Nov 90 01:56:01 GMT
Sender: root@crash.cts.com
Organization: People-Net [pnet01], El Cajon CA
Lines: 40

kjh@aludra.usc.edu (Kenneth J. Hendrickson) writes:
>I have learned that on the NeXT (and possibly other *nix systems), there
>is a /etc/disktab animal that lists characteristics of disks, much like
>/etc/termcap lists the capabilities of a terminal.  This sounds like a
>good idea to me.  The kernel could read this file and configure itself
>for the correct number of tracks, sectors, cylinders, heads, etc.  Thus
>this information would not need to be hardcoded into the kernel as it is
>now.  I don't know much about disk controllers, but could this help the
>compatibility problem, and development of SCSI and ESDI device drivers?

SunOS has something called /etc/format.dat.  All that basically does is tell
the generic driver the physical parameters of the disk.  Very similiar to the
ISA drive types in your AT BIOS table.  If the Sun is equiped with multiple
controllers, then that is also part of the format.dat entry.

Help the development?  All this would eliminate would be the need to hardcode
the hard drive parameters.  It does NOT circumvent or make writing a device
driver for a given hard drive controller any easier.  You still have the
problem (especially with SCSI host adaptors) that every manufacturer does it
differently.

>It is kind of "begging the question" to use this if you are booting from
>a hard disk, but it makes perfect sense if you are booting from a
>floppy.
>
>What say the device driver gods?

Admittedly, it is a nice idea, but first you need a working device driver for
brand X hard drive controller.
 
     // JCA

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