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DateSat, 21 Jan 2006 12:05:53 +0100
FromHarald Welte <>
SubjectRe: Iptables error
On Fri, Jan 20, 2006 at 11:46:13AM -0800, David S. Miller wrote:

> Your struct won't be 8-byte aligned either as far as I can tell on
> x86_64.

According to my tests, the struct is 8-byte-aligned on x86_64, and
that's how I'd like it to be.

Please don't ask me why it happens, I know that the alignment constraint
of a u64 on x86_64 is only 4. But at least gcc-3.3.6 and gcc-4.0.3
(debian) result in __alignof__ of that test structure (and a 'u_int64_t
alone') to 8 bytes.

When it comes to these things, I can only do trial+error.

Maybe it's because __alignof__ returns the recommended alignment, not
the required alignment.

> We need to use the aligned_u64 thing if you want that.

That should make sure that we always get what we want, yes.

--
- Harald Welte <laforge@netfilter.org> http://netfilter.org/
============================================================================
"Fragmentation is like classful addressing -- an interesting early
architectural error that shows how much experimentation was going
on while IP was being designed." -- Paul Vixie[unhandled content-type:application/pgp-signature]
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