linux-kernel - Re: [PATCH RFC] x86: fix confusing name of /proc/cpuinfo "ht" flag

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Message-ID: <4AFBB45A.9000606@zytor.com>
Date:	Wed, 11 Nov 2009 23:08:10 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Dave Jones <davej@...emonkey.org.uk>
Subject: Re: [PATCH RFC] x86: fix confusing name of /proc/cpuinfo "ht" flag

On 11/11/2009 10:59 PM, Ingo Molnar wrote:
> 
> * Bartlomiej Zolnierkiewicz <bzolnier@...il.com> wrote:
> 
>> "ht" flag indicates only ability to detect siblings not HT presence 
>> itself.
>>
>> Inspired by:
>> http://www.codemonkey.org.uk/2009/11/10/common-hyperthreading-misconception/
> 
> i think instead of changing 'ht' to 'ht_detect', it would be even more 
> intuitive to only expose the 'ht' flag if the ht-detect capability is 
> there _and_ if the number of siblings is 2 or more.
> 
> That way we dont change it - we just 'hide' the 'ht' string on the 
> category of systems that can enumerate HT via the CPUID but dont 
> actually have HyperThreading.
> 

/proc/cpuinfo is a user-space visible ABI.  Changing it is bad chicken.

	-hpa

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

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