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Date: Tue, 12 Feb 2013 09:35:12 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Linus Torvalds <torvalds@linux-foundation.org>
CC: "H.J. Lu" <hjl.tools@gmail.com>, Ingo Molnar <mingo@kernel.org>,
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Subject: Re: [tip:x86/mm] x86, mm: Use a bitfield to mask nuisance get_user()
 warnings
References: <20130209110031.GA17833@n2100.arm.linux.org.uk> <tip-b390784dc1649f6e6c5e66e5f53c21e715ccf39b@git.kernel.org> <CA+55aFxaUUMQuw3bgLbZLARp05eM19E_qTXBYePPk9mvEsSp=g@mail.gmail.com> <5119C34B.70207@zytor.com> <CAMe9rOrTLGJvO+Z8kCG3gmOuW-Yq2Ex9WMfJZ5wmZcbz+zm94Q@mail.gmail.com> <CA+55aFwMr8pDfj+wuv=-tUFqZQOhnqkwC7tVq-S=4MGGWiqz1A@mail.gmail.com> <511A7892.4020407@zytor.com> <CA+55aFz=OnntmRvi6geuL7ccC6ncwQ7NvURDcwu87BkpS3H0TQ@mail.gmail.com>
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On 02/12/2013 09:32 AM, Linus Torvalds wrote:
> On Tue, Feb 12, 2013 at 9:14 AM, H. Peter Anvin <hpa@zytor.com> wrote:
>>
>> No, I think what he is talking about it this bit:
>
> Ok, I agree that the bitfield code actually looks cleaner.
>
> That said, maybe gcc has an easier time using a few odd builtins and
> magic typeof's. But at least the bitfield trick looks half-way
> portable..
>

On the other hand, it still uses two gcc extensions: long long bitfields 
and typeof.

I'll see what kind of code we get with the macro.

	-hpa


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