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Date:      Sat, 28 Feb 1998 12:48:44 +1030
From:      Greg Lehey <grog@lemis.com>
To:        Mike Smith <mike@smith.net.au>
Cc:        FreeBSD Hackers <hackers@FreeBSD.ORG>
Subject:   Re: Kernel debugging: what's going on here?
Message-ID:  <19980228124844.00033@freebie.lemis.com>
In-Reply-To: <199802280214.SAA00165@dingo.cdrom.com>; from Mike Smith on Fri, Feb 27, 1998 at 06:14:02PM -0800
References:  <19980228123253.24049@freebie.lemis.com> <199802280214.SAA00165@dingo.cdrom.com>

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On Fri, 27 February 1998 at 18:14:02 -0800, Mike Smith wrote:
>> On Fri, 27 February 1998 at 17:56:46 -0800, Mike Smith wrote:
>>> Yes, I noticed.  But rewriting the bp on the fly is not uncommon; quite
>>> a few device drivers do it, it wouldn't surprise me if it wasn't done
>>> elsewhere rather than cloning the original.
>>
>> Sure, all sorts of things modify the buffer header.  But you're still
>> missing the point: the processor is stopped here, it's in the
>> debugger.  No instructions were executed between the two views.  You
>> might just as well take a look at a dump.  Since when does the content
>> of memory differ depending on where you look at it from?
>
> Whoops.  OK, are we sure that "bp" points to the same type in both
> cases?

Not any more :-)  Somebody else replied first.

> And more importantly, that bp->b_vp is expected to be the same type?

Yes, it was.

> (Yes, this is *really* clutching at straws).  There's not much else
> short of a GDB bug that I can think of that would cause this.

Thanks.  I should have seen this myself, but sometimes you end up
looking in the wrong place.

Greg

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