Re: [PATCH] x86: Remove readq()/writeq() on 32-bit

From: H. Peter Anvin
Date: Wed May 13 2009 - 17:06:58 EST


Jeff Garzik wrote:
>
> Roland's patch was acked, apparently, _in spite of_ the commonly
> accepted readq() definition already being in use!
>
> Thusfar, I see two things:
>
> (1) years of history has shown that non-atomic readq/writeq on 32-bit
> platforms has been sufficient, based on testing and experience. In
> fact, in niu's case, a common readq/writeq would have PREVENTED a bug.
>
> (2) unspecified fears continue to linger about non-atomicity
>
> We should not base decisions on fear, particularly when the weight of
> evidence and experience points in the other direction.
>

I have personally dealt with at least one device who'd want to opt out
of a standard readq/writeq (it's not in-tree because it never shipped,
unfortunately.) Doing the opt-in headers seems like a reasonable thing
to do to me, but perhaps I'm just being overly paranoid.

-hpa

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