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From: Wolfgang Helbig <helbig@MX.BA-Stuttgart.De>
Message-Id: <199703161651.RAA02230@helbig.informatik.ba-stuttgart.de>
Subject: Re: wd driver questions
In-Reply-To: <199703161530.IAA03754@seagull.rtd.com> from Don Yuniskis at "Mar 16, 97 08:30:41 am"
To: dgy@rtd.com (Don Yuniskis)
Date: Sun, 16 Mar 1997 17:51:05 +0100 (MET)
Cc: hackers@freebsd.org
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> Greetings and Hallucinations!
> 

> 
> It appears that boot.c uses the disk geometry obtained from the
> BIOS (I think getdiskinfo() or something like that which looks
> at the disk parameter table entry for each disk).  Is this
> correct?

Think so.

> However, the probe for wd appears to query the drive (with an
> IDENTIFY command) to obtain these parameters.  Is this also
> correct?

Think so.

> And, how (if at all) does the geometry written to the disklabel
> figure into the operation/calculations of the driver?

As far as I could decipher from the driver code (wd.c) the probed geometry
is used only to read the label. From there on the geometry read from the
label is used exclusively by the driver. Both are the same, if you
disklabel auto.
But I'm not really sure about my findings.

> 
> Thx!
> --don
>