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Bug 137344

Summary:	Cannot disable hyperthreading on x86_64 platform
Product:	Red Hat Enterprise Linux 3	Reporter:	David Lehman <dlehman>
Component:	kernel	Assignee:	Jim Paradis <jparadis>
Status:	CLOSED ERRATA	QA Contact:	Brian Brock <bbrock>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	3.0	CC:	agrajag, peterm, petrides, riel, tao
Target Milestone:	---
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	RHSA-2006-0144	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2006-03-15 15:44:25 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	168424

Description David Lehman 2004-10-27 17:27:56 UTC

Description of problem:
x86_64 doesn't support disabling hyperthreading via the 'noht' kernel
option. This means that the only way to disable hyperthreading via
kernel arguments is with "acpi=off", which is known to break/disable
quite a few things and thus is not a viable alternative

Version-Release number of selected component (if applicable):
kernel-2.4.21-20.EL

How reproducible:
Always

Steps to Reproduce:
1. Boot x86_64 kernel with "noht" parameter
2. 
3.
  
Actual results:
Hyperthreading is still enabled

Expected results:
Hyperthreading is disabled

Additional info:

Comment 1 Jim Paradis 2004-10-29 05:17:49 UTC

*** Bug 137101 has been marked as a duplicate of this bug. ***

Comment 3 Jim Paradis 2004-12-03 17:26:57 UTC

It should be pretty straightforward to duplicate what we do on the x86
side, modulo some differences in ACPI handling.  I see this as
perfectly doable in the U5 timeframe.

Comment 6 Eric Hagberg 2005-04-27 21:23:07 UTC

So it should be getting fixed in U5?

Comment 7 Jim Paradis 2005-04-27 21:52:22 UTC

No, this didn't make U5.  I'm testing the patch now that should be slated for U6.

Comment 16 Ernie Petrides 2005-10-20 05:42:12 UTC

A fix for this problem has just been committed to the RHEL3 U7
patch pool this evening (in kernel version 2.4.21-37.6.EL).

Comment 21 Red Hat Bugzilla 2006-03-15 15:44:25 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2006-0144.html