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

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Message-ID: <20091112183718.GA1925@codemonkey.org.uk>
Date:	Thu, 12 Nov 2009 13:37:18 -0500
From:	Dave Jones <davej@...emonkey.org.uk>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] x86: fix confusing name of /proc/cpuinfo "ht" flag

On Thu, Nov 12, 2009 at 06:59:08PM +0100, Ingo Molnar wrote:
 > > It's an ABI.  Keep it stable, please.
 > 
 > That's generally true, but i'm not suggesting that: i'm suggesting to 
 > _clear_ the HT flag from the cpufeatures if there's only one sibling. 
 > It's meaningless in that case and as the link quoted by the original 
 > patch shows many people are confused by that.
 > 
 > I have such a box so i can test it. (but i dont expect any problems)

I agree that it's an ABI change, but any software depending on its current
state has to implement a fallback for the case where 'ht' isn't present anyway
unless there's some program that only runs on ht capable hardware, which
sounds just crazy.

The only potential for breakage that I can see is that code that is tuned
to be run in the HT case will stop running in cases where it shouldn't.
Which sounds like a positive thing to me.

	Dave

-- 
http://www.codemonkey.org.uk
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