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Subject: Re: config/hints changes: panic booting pcvt kernel
In-Reply-To: <XFMail.000713103729.steveo@eircom.net> from Steve O'Hara-Smith at "Jul 13, 0 10:37:29 am"
To: steveo@eircom.net (Steve O'Hara-Smith)
Date: Fri, 14 Jul 2000 16:46:42 +0200 (METDST)
Cc: hm@hcs.de, peter@FreeBSD.ORG, dcs@newsguy.com,
	freebsd-current@FreeBSD.ORG
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Organization: HCS Hanseatischer Computerservice GmbH
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From: hm@hcs.de (Hellmuth Michaelis)
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From the keyboard of Steve O'Hara-Smith:
> On 13-Jul-00 Hellmuth Michaelis wrote:
> > I'm now completely out of ideas ....
> 
>         Try and pin down which printf really makes a difference ?

Ok, did that. Surprise: i removed all the debugging code and all changes
i made to track down what happenes in the kbd driver as well as the pcvt
driver - everything now is completely as it was and it tracks down to
a single printf in /sys/dev/kbd.c: adding it lets a pcvt kernel boot
as happily as before, removing this printf gives the described panic:

	/* find the keyboard specified by a driver name and a unit number */
	int
	kbd_find_keyboard(char *driver, int unit)
	{
        	int i;

	printf("kbd_find_keyboard\n");
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^        
	        for (i = 0; i < keyboards; ++i) {
	...

I'm currently re-cvsupping/recompiling a completly fresh tree to reproduce
this to make shure it is really this single printf. Also i will try out
something to make shure it is not a timing problem somewhere.

>         I recall a long time ago a bit of code that had calls to a function
> that did nothing, the comment was that it prevented an MSC optimiser bug from
> screwing things up.

Oh oh ... 

I would really appreciate it if someone else would have a look at this.

hellmuth
-- 
Hellmuth Michaelis                                    Tel   +49 40 55 97 47-70
HCS Hanseatischer Computerservice GmbH                Fax   +49 40 55 97 47-77
Oldesloer Strasse 97-99                               Mail  hm [at] hcs.de
D-22457 Hamburg                                       WWW   http://www.hcs.de


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