Date: Sat, 24 Nov 2007 18:28:22 +0000
From: Luciano Rocha <strange@nsk.no-ip.org>
To: Pierre Ossman <drzeus-list@drzeus.cx>
Cc: Daniel Drake <dsd@gentoo.org>, linux-kernel@vger.kernel.org,
       davem@davemloft.net, kune@deine-taler.de, johannes@sipsolutions.net
Subject: Re: [RFC] Documentation about unaligned memory access
Message-ID: <20071124182822.GB17654@bit.office.eurotux.com>
Mail-Followup-To: Luciano Rocha <strange@nsk.no-ip.org>,
	Pierre Ossman <drzeus-list@drzeus.cx>,
	Daniel Drake <dsd@gentoo.org>, linux-kernel@vger.kernel.org,
	davem@davemloft.net, kune@deine-taler.de, johannes@sipsolutions.net
References: <20071123001554.12F8B9D4A1F@zog.reactivated.net> <20071124143441.41657307@poseidon.drzeus.cx> <20071124155052.GA15440@bit.office.eurotux.com> <20071124171931.699aa1ff@poseidon.drzeus.cx> <20071124172236.GA16944@bit.office.eurotux.com> <20071124183525.13c41374@poseidon.drzeus.cx>
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On Sat, Nov 24, 2007 at 06:35:25PM +0100, Pierre Ossman wrote:
> On Sat, 24 Nov 2007 17:22:36 +0000
> Luciano Rocha <strange@nsk.no-ip.org> wrote:
>=20
> > On Sat, Nov 24, 2007 at 05:19:31PM +0100, Pierre Ossman wrote:
> > > It most certainly does not. gcc will assume that an int* has int alig=
nment. memcpy() is a builtin, which gcc can translate to pretty much anythi=
ng. And C specifies that a pointer to foo, will point to a real object of t=
ype foo, so gcc can't be blamed for the unsafe typecasts. I have tested thi=
s the hard way, so this is not just speculation.
> >=20
> > Yes, on *int and other assumed aligned pointers, gcc uses its internal
> > version.
> >=20
> > However, my point is that those pointers, unless speaking of packed
> > structures, can safely be assumed aligned, while char*/void* can't.
> >=20
>=20
> I get the sensation we're violently in agreement here, just misunderstand=
ing each other. :)

That's it. :)

Sorry for the noise,...

--=20
lfr
0/0

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