From owner-freebsd-alpha  Sun Mar  4 17:10:15 2001
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Date: Sun, 4 Mar 2001 17:10:02 -0800 (PST)
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From: Matthew Jacob <mjacob@feral.com>
Subject: Re: alpha/25535: unaligned access crash on stq
Reply-To: Matthew Jacob <mjacob@feral.com>
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The following reply was made to PR alpha/25535; it has been noted by GNATS.

From: Matthew Jacob <mjacob@feral.com>
To: User Raymond <raymond@one.com.au>
Cc: freebsd-gnats-submit@FreeBSD.ORG
Subject: Re: alpha/25535: unaligned access crash on stq
Date: Sun, 4 Mar 2001 17:02:21 -0800 (PST)

 (let's keep the audit trail in the PR)
 
 On Mon, 5 Mar 2001, User Raymond wrote:
 
 > Subj: alpha/25535: unaligned access crash on stq
 > To:   mjacob@feral.com
 > From: raymond@one.com.au
 > 
 > 
 > > How is this a bug? If you try and access unaligned values you'll get
 > > unaligned traps.
 > 
 > Sorry - I didn't explain myself at all well did I?
 > 
 > The example was the only way I could force that to happen and I don't
 > know whether the OS is supposed to trap that and fix it on the fly.
 > 
 > The original is in a much larger piece of code that ends up with a structure
 > unalligned and I can't work out how to get around it.  I am porting the
 > code from the x86 platform and not having much luck.
 > 
 > Any pointers would be appreciated.
 > 
 > Ray Newman
 > 
 
 Pointers indeed! :-)
 
 farrago.feral.com > uname -a
 FreeBSD farrago.feral.com 4.2-STABLE FreeBSD 4.2-STABLE #6: Sun Mar  4
 13:33:54 PST 2001     mjacob@farrago.feral.com:/tstsys/compile/GPLUS  alpha
 farrago.feral.com > sysctl -a|grep alig
 vfs.nfs.realign_test: 20065
 vfs.nfs.realign_count: 0
 machdep.unaligned_print: 1
 machdep.unaligned_fix: 1
 machdep.unaligned_sigbus: 0
 
 
 If you set machdep.unaligned_fix to 0, it will stop fixups. The default is to
 do the fixup. If you set machdep.unaligned_print to 0, it won't print.
 
 You might consider how to get the structure aligned as it's much more than
 just alpha that has this issue.
 
 -matt
 
 

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