Re: [PATCH] x86: avoid pointless fields of struct cpuinfo_x86

From: H. Peter Anvin
Date: Wed Apr 27 2011 - 21:07:46 EST


On 04/27/2011 08:07 AM, Jan Beulich wrote:
> Several of the flag fields of this structure are completely unused in
> certain (common) configurations. Don't pointlessly reserve space for
> them, and have truly flag-only fields consume a single bit only.
>
> Make functionality detection conditional upon (partly new) config
> options that are now also used to control the presence of those
> fields.

If you're going to make them bitflags, please use the features array we
already have. I do not think there is any point in compressing the
array if we're not doing something epicly wrong.

One thing I would like to see is to move the bug flags into an array
separate from the features array; the bug array should be OR'd together
(if there is a bug on any CPU, it is here) instead of AND'ed; or we
could just put them into the features array with negative logic (the
lack of a bug is a feature.)

That way we get to reuse all of our machinery.

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

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