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Date: Thu, 18 Jan 2007 20:18:23 +0100
From: Olivier Houchard <mlfbsd@ci0.org>
To: ticso@cicely.de
Message-ID: <20070118191823.GB42638@ci0.org>
References: <20070111101528.GV80390@cicely12.cicely.de>
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Cc: Bernd Walter <ticso@cicely12.cicely.de>, freebsd-arm@freebsd.org
Subject: Re: memcpy limitation
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On Thu, Jan 11, 2007 at 11:15:28AM +0100, Bernd Walter wrote:
> I get a sigbus with the following:
> #0  0x00033158 in $a () at lcp.c:939
> 939           memcpy(&req, opt, sizeof req);
> (gdb) print req
> $1 = {hdr = {id = 0 '\0', len = 0 '\0'}, proto = 0, period = 0}
> (gdb) print &req
> $2 = (struct lqrreq *) 0xbfffe4a0
> (gdb) print opt
> $3 = (struct fsm_opt *) 0xbfffe5b6
> 
> Shouldn't memcpy work with any alignment?
> 

It certainly does. Would you have a simple test case which reproduce this ?
Or does it happen as soon as you try to do an unaligned copy ?
I'm quite confused on why it would happen, memcpy is shared between the kernel
and the userland, and in kernel I'm sure it does unaligned copies. 

Thanks,

Olivier