From owner-freebsd-alpha  Wed Feb 14 10:51:23 2001
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From: Andrew Gallatin <gallatin@cs.duke.edu>
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Date: Wed, 14 Feb 2001 13:50:36 -0500 (EST)
To: Peter.Blok@inter.NL.net
Cc: freebsd-alpha@FreeBSD.ORG
Subject: Re: unaligned access
In-Reply-To: <200102141536.QAA03471@altrade.nijmegen.inter.nl.net>
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Peter.Blok@inter.NL.net writes:
 > Hi,
 > 
 > I am trying to port mpd-netgraph to alpha, but i'm getting a lot of uac's. I am trying to use gdb, but I am not used to gdb. When I try to lookup the address it tells me it is outside the map.
 > 
 > Is it possible to make it core dump instead of this warning? It would be nice if you can say: run this command and core dump on uac.
 > 
 > Are tools available to determine in which function the uac takes place? I can make something myself with perl and nm, but if there is already something out there?
 > 
 > Which compiler options bring this up at compile time?
 > 
 > Peter

I don't know what mpd netgraph is.  Can you elaborate further?  Is the
kernel crashing, or is it a userland app?

If it is a userland app, try running uap -s prior to invoking gdb.
Then run gdb on the app.  You should get a SIGBUS at the PC of the
unaligned access.  If gdb misbehaves, try increasing the size of the 
heuristic-fence-post.  Eg:

(gdb) set heuristic-fence-post 0xffffffffffffffff 

Hope this helps,

Drew


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