Messages in this thread | | | Date | Wed, 24 Nov 1999 13:34:54 +0100 | From | Jamie Lokier <> | Subject | Re: [patch] smp-2.3.29-B2, spinlocks, reboot |
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Robert Redelmeier wrote: > My understanding is that you don't have a chance of atomicity unless > the address is aligned [so it won't cross cache lines]. I've observed > gcc being very poor at alignment, inserting .align 2 when .align 4 would > have been better. And gas using the last given .align when there are > multiples. So movb is a good idea. Or is there something else?
The movb is a smaller instruction, that's all. There is no alignment problem -- spinlocks are always properly aligned.
If gcc is inserting .align 2 in ELF output, that should be because the object/structure only requires 2 byte alignment. I.e., the largest element is a short. .align 2 is perfectly normal in a.out output, where it means "align to 1<<2".
-- Jamie
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