Messages in this thread | | | Date | Fri, 04 Aug 2006 12:04:57 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [RFC][PATCH] A generic boolean |
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Jes Sorensen wrote: >> >> And what will break if you make that switch? > > If we are lucky, some binary only modules? :-) > > But you're right, it may just have to be documented as one of those > nasty issues to watch out for. >
What is really poisonous is structures which get padded when all the members are naturally aligned. Unfortunately gcc produces really crap code with __attribute__((packed)) on some architectures, so just using that isn't a good solution. On the other hand, non-AEABI ARM sometimes needs it!
For the lack of a __attribute__((nopad)) that would throw a warning or error on excessive padding, I fear that our best option is an __abi annotation which would enforce certain rules using sparse, and presumably provide __attribute__((packed)) on ARM:
- All padding must be explicit. - All members must be naturally aligned. - No unportable constructs, like non-int-sized bitfields.
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