Re: atomic64_t proposal

From: Andi Kleen (ak@suse.de)
Date: Tue Aug 27 2002 - 14:58:45 EST


Dean Nelson <dcn@sgi.com> writes:

> I'm proposing the creation of an atomic64_t variable, which is a 64-bit
> version of atomic_t, and the usage of the __typeof__ keyword in macro versions
> of the atomic operations to enable them to operate on either type (atomic_t and
> atomic64_t).
>
> I submitted the following patch to David Mosberger to be considered for
> inclusion in the IA-64 linux kernel. He suggested that I bring the topic up
> on this list so that the other 64-bit platform maintainers can commment.

Wouldn't it be much cleaner to just define atomic64_add/sub/read etc. ?
That would make the macros much nicer.

On x86-64 it would be fine this way.

Is it supposed to only work on 64bit or do you plan to supply it for 32
bit too? If no, I don't see how drivers etc. should ever use it. linux
is supposed to have a common kernel api.
If yes, the implementation on 32bit could be a problem. e.g. some
archs need space in there for spinlocks, so it would be needed to limit
the usable range.

-Andi
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