Date: Sun, 12 Nov 2006 20:14:37 +0300 From: Ruslan Ermilov <ru@freebsd.org> To: Giorgos Keramidas <keramida@freebsd.org>, arm@freebsd.org, current@freebsd.org Subject: Re: [head tinderbox] failure on arm/arm Message-ID: <20061112171436.GF50349@rambler-co.ru> In-Reply-To: <20061112165904.GP6501@plum.flirble.org> References: <20061112133929.9194773068@freebsd-current.sentex.ca> <20061112140010.GA47660@rambler-co.ru> <20061112142710.GE91556@wombat.fafoe.narf.at> <20061112133929.9194773068@freebsd-current.sentex.ca> <20061112140010.GA47660@rambler-co.ru> <20061112144230.GC2331@kobe.laptop> <20061112145151.GC49703@rambler-co.ru> <20061112151150.GA2988@kobe.laptop> <20061112155723.GB50349@rambler-co.ru> <20061112165904.GP6501@plum.flirble.org>
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On Sun, Nov 12, 2006 at 04:59:04PM +0000, Nicholas Clark wrote:
> On Sun, Nov 12, 2006 at 06:57:23PM +0300, Ruslan Ermilov wrote:
> > So your sizeof() argument, well... I don't understand it and it
> > doesn't make things clearer at least to me. I still believe this
> > is bug in GCC that the alignment requirement is so high for a
> > "struct foo { char x; }" (there's no real reason for this!).
>=20
> It is no bug in GCC. ANSI C gives extreme flexibility for the compiler to
> align (or pad) structures. The assumptions in the code you presented are =
not
> portable. The problem tends to be that ARM is the only common platform th=
at
> does structure alignment this way, so tends to trip up a lot of code that
> has worked just fine in many other places.
>=20
> There is a lot more detail in
> http://netwinder.osuosl.org/users/b/brianbr/public_html/alignment.html
> including how gcc's __packed__ extention can be used to tell gcc to align
> structures in different ways.
>=20
Thanks! Item 2 at this URL has an answer to my question.
Cheers,
--=20
Ruslan Ermilov
ru@FreeBSD.org
FreeBSD committer
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