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From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no>
To: Bruce Evans <brde@optusnet.com.au>
References: <200907081526.n68FQYDb055185@svn.freebsd.org>
	<20090709041145.G46111@delplex.bde.org>
Date: Thu, 09 Jul 2009 17:41:28 +0200
In-Reply-To: <20090709041145.G46111@delplex.bde.org> (Bruce Evans's message of
	"Thu, 9 Jul 2009 04:24:46 +1000 (EST)")
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Cc: svn-src-projects@freebsd.org, src-committers@freebsd.org,
	Rui Paulo <rpaulo@freebsd.org>
Subject: Re: svn commit: r195460 - projects/mesh11s/sys/net80211
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Bruce Evans <brde@optusnet.com.au> writes:
> Broken ABIs (e.g., arm?) may add padding at the end of structs,

Padding at the end of a struct is *required* to ensure proper alignment
of the next element in an array, e.g.

struct foo { int i; char c; } bar[2];

Assuming a four-byte alignment requirement for int, the compiler *must*
add three bytes of padding at the end of struct foo so bar[1].i is
correctly aligned.

cf. ISO/IEC 9899:1999 =C2=A76.7.2.1:

15 There may be unnamed padding at the end of a structure or union.

DES
--=20
Dag-Erling Sm=C3=B8rgrav - des@des.no