*BSD News Article 2642


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Newsgroups: comp.unix.bsd
Path: sserve!manuel!munnari.oz.au!mips!mips!darwin.sura.net!cs.ucf.edu!tarpit!newspost
From: jbh@aii.com
Subject: Re: 386bsd-0.1: primary bootstrap (wdbootblk.c) problem & fix.
Message-ID: <1992Jul28.114831.29782@pixie.aii.com>
Keywords: 386bsd boot bootstrap wdbootblk.c
Sender: newspost@pixie.aii.com
Organization: Automation Intelligence
References: <1992Jul27.172708.3363@gateway.novell.com> <greg.712261295@hibp1.ecse.rpi.edu> <1992Jul27.192502.15727@gateway.novell.com>
Date: Tue, 28 Jul 1992 11:48:31 GMT

In article <1992Jul27.192502.15727@gateway.novell.com> terry@npd.Novell.COM (Terry Lambert) writes:
>In article <greg.712261295@hibp1.ecse.rpi.edu> greg@ecse.rpi.edu (Greg) writes:
>>Terry, please reread my message. THIS IS NOT THE SAME BUG!!!!!!
>>This problem is in wdbootblk.c. The code contained in wd.c has not
>>even been loaded off the disk at the point when this hang occurs! 
>>To understand what is going on, study wdbootblk.c.
>
>	I think I goofed in recommending the wd.c fix for this problem;
>however, the status register being polled after the delay is wd_status,
>and I still believe that a canonical fix would be looking at wd_altsts
>instead.

  You have totally missed it ! wd_altsts is BOGUS period. Read your
IBM Tech ref. manual, the register is READ ONLY and only 4 bits wide. It
ain't good for anything when bieng read !!!!! Read the Western Digital
Manual, a read of this register is good only to provide a VENDOR ID number,
on a REAL W.D. chip it ALWAYS returns a FIXED value regardless of the
status of the controller. The 'patch' simply used wd_status to obtain the
REAL status of the controller ! This is the proper way!!!!!
>
>	Greg's delay loop will have the same effect -- that is, making sure
>the controller has finished it's reset prior to using it.
>

The DELAY loop method is still dancing through raindrops and is NOT safe
for ALL combinations of CPU-speed and MFM/RLL controllers.

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