Messages in this thread | | | Date | Wed, 19 Jan 2011 11:18:57 -0500 | From | Mathieu Desnoyers <> | Subject | Re: Bug#609371: linux-image-2.6.37-trunk-sparc64: module scsi_mod: Unknown relocation: 36 |
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* Sam Ravnborg (sam@ravnborg.org) wrote: > > > > If my memory serves me correctly, I think "long long" is aligned on 4 bytes on > > ppc32, but on 8 bytes on x86_32 (yeah, that's weird). How about we create a > > #define __long_long_aligned __attribute__((__aligned__(__alignof__(long long)))) > > #define __u64_aligned __attribute__((__aligned__(__alignof__(long long)))) > > A bit shorter but maybe less obvious.
Yep, that would make sense.
I'm tempted to try creating
#defined __u64_packed_aligned __attribute__((__packed__, __aligned__(__alignof__(long long))))
in the hope that gcc sees this as a strict alignment requirement (including a max bound) rather than just a hint. From what I gather in my reading of
http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html
"The aligned attribute can only increase the alignment; but you can decrease it by specifying packed as well. See below."
gcc seems to support having both specified. I think this would provide the kind of alignment guarantees we really need here: both specifying the minimum _and_ maximum alignment.
Thoughts ?
Mathieu
> > Sam
-- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com
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