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Date:      Mon, 04 Feb 2002 07:08:29 +1100
From:      Peter Jeremy <peter.jeremy@alcatel.com.au>
To:        Volker Stolz <stolz@hyperion.informatik.rwth-aachen.de>
Cc:        alpha@FreeBSD.ORG
Subject:   Re: rpc.statd/SIOCGIFCONF revisited
Message-ID:  <20020204070828.B70935@gsmx07.alcatel.com.au>
In-Reply-To: <20020130224621.A14154@i2.informatik.rwth-aachen.de>; from stolz@hyperion.informatik.rwth-aachen.de on Wed, Jan 30, 2002 at 10:46:21PM %2B0100
References:  <20020130224621.A14154@i2.informatik.rwth-aachen.de>

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On Wed, Jan 30, 2002 at 10:46:21PM +0100, Volker Stolz wrote:
>Now the userland code in e.g. libc/rpc/get_myaddress.c memcpy tried
>now to access XX which obviusly isn't at an 8 byte aligned address.
>
>memcpy() *should* be able to copy this region. *But*:
>memcpy() gets optimized by gcc to use floating point registers
>(unless you specify -fno-builtin). These instructions can only work
>on double word aligned data :-/

This is a bug in gcc - memcpy() must be able to handle arbitrarily
aligned operands.

> Something similar happens when you use an assignment like foo = *bar.

This is reasonable.  bar must be correctly aligned unless you're doing
something unportable.

Peter

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