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Date:      Sun, 19 Apr 1998 04:56:51 -0400
From:      Mark Mayo <mark@vmunix.com>
To:        Bruce Evans <bde@zeta.org.au>
Cc:        hardware@FreeBSD.ORG
Subject:   Re: best wdc0 flags ?
Message-ID:  <19980419045651.63169@vmunix.com>
In-Reply-To: <199804190652.QAA23558@godzilla.zeta.org.au>; from Bruce Evans on Sun, Apr 19, 1998 at 04:52:34PM %2B1000
References:  <199804190652.QAA23558@godzilla.zeta.org.au>

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On Sun, Apr 19, 1998 at 04:52:34PM +1000, Bruce Evans wrote:
> >Damn.. I just tried doing a
> >	dd if=/dev/rwd0 of=/dev/null bs=1m count=1280

> >Any ideas what's going wrong here?
> 
> Your BIOS is misconfigured or only supports slow PIO modes.  I use AUTO
> mode and checked that this gave 16.6MB/sec by looking at `systat -vmstat'
> (interrupt overhead should be about 10/16.6 * 100% for a 10 MB/sec drive).
> My BIOS also supports PIO modes 0, 1, 2, 3 and 4.  The 10MB firehose
> swamps at least PIO modes 0 and 1.

I see what's happening now.. The boot drive on this system is a SCSI
disk, and when I added the IDE drive the BIOS absolutely refused to
boot off the SCSI (even though it was set to..) -- so I set the 
"primary master" to "NONE" and let the BIOS think there was only
the SCSI. Naturally, FreeBSD picked up the IDE just fine, but apparently
the controller is operating in PIO mode 0 or 1, and as you say it
just can't keep up with the Fireball...

Ugly situation.  :-)

The machine is remote, so playing around more is a pain. Perhaps I'll
try setting the BIOS to "auto" like you said, but not run the IDE
AutoDetect thing and see if that works.. otherwise I don't know how
I can get it to boot off the damned SCSI drive without using a floppy
(which makes me nervous since the box is far enough away to be a real pain
to get on the console..)

Thanks for the superb explanation.

-Mark

> 
> Bruce

-- 
------------------------------------------------------------------------
 Mark Mayo		  				mark@vmunix.com       
 RingZero Comp.  	  		    http://www.vmunix.com/mark 

	 finger mark@vmunix.com for my PGP key and GCS code
------------------------------------------------------------------------
 "The problem is how do you build tools that understand your programs
  at a deeper semantic level." - James Gosling

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