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Date: Tue, 19 Nov 2002 21:42:42 +0000 (GMT)
From: Hugh Dickins <hugh@veritas.com>
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To: Steffen Persvold <sp@scali.com>
cc: linux-kernel@vger.kernel.org
Subject: Re: [BUG?] Xeon with HyperThreading and linux-2.4.20-rc2
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On Tue, 19 Nov 2002, Steffen Persvold wrote:
> 
> I've two boxes with Dual Xeons 1.8 GHz and HT option enabled in BIOS. When 
> I boot 2.4.20-rc2 with default arguments the kernel detects 4 processors and 
> also reports 4 processors in /proc/cpuinfo wiht the "ht" feature.
> 
> However, if I boot with the "noht" option (wich I believed turned off HT 
> and therefore only two processors should be available), the kernel still 
> detects 4 processors, _but_ now the "ht" feature in /proc/cpuinfo is not 
> there. Is this the intention of the "noht" option ?

No, the intention of the "noht" option is as you believed, and it used to
work that way.  I looked at latest sourcec, didn't see anything obviously
wrong.  Sorry, but I don't have a suitable HT machine to check at present.

> If so, are there any 
> options available to turn off HT support in the kernel completely, so that 
> I don't have to go into the BIOS to turn it off ?
> 
> If you want to I can provide the dmesg output and .config.
> 
> I think this issue is not just related to 2.4.20-rc2, but earlier kernels 
> aswell.

Could others check and report if 2.4.20-rc2 "noht" works for them or not?

Thanks,
Hugh

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