From owner-freebsd-stable@FreeBSD.ORG Sun Nov 13 23:39:20 2005 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4626C16A41F for ; Sun, 13 Nov 2005 23:39:20 +0000 (GMT) (envelope-from dwhite@gumbysoft.com) Received: from carver.gumbysoft.com (carver.gumbysoft.com [66.220.23.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5499243D49 for ; Sun, 13 Nov 2005 23:39:19 +0000 (GMT) (envelope-from dwhite@gumbysoft.com) Received: by carver.gumbysoft.com (Postfix, from userid 1000) id 38B2372DD4; Sun, 13 Nov 2005 15:39:19 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by carver.gumbysoft.com (Postfix) with ESMTP id 341EA72DCB; Sun, 13 Nov 2005 15:39:19 -0800 (PST) Date: Sun, 13 Nov 2005 15:39:19 -0800 (PST) From: Doug White To: kama In-Reply-To: <20051111204659.F8860@ns1.as.pvp.se> Message-ID: <20051113153531.B7337@carver.gumbysoft.com> References: <20051111204659.F8860@ns1.as.pvp.se> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: freebsd-stable@freebsd.org Subject: Re: Hyperthreading issues. X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 13 Nov 2005 23:39:20 -0000 On Fri, 11 Nov 2005, kama wrote: > Just upgraded from 5.4 to 6.0 and hyperthreading stoped working. > Everything looks ok, but it doesn't use two of the logical CPU's. This is disabled by default due to a information-leak vulnerability across the hyperthreaded cores. The details from the release notes: Because of an information disclosure vulnerability on processors using Hyper-Threading Technology (HTT), the machdep.hyperthreading_allowed sysctl variable has been added. It defaults to 1 (HTT enabled) on FreeBSD CURRENT, and 0 (HTT disabled) on the 4-STABLE and 5-STABLE development branches and supported security fix branches. More information can be found in security advisory FreeBSD-SA-05:09.htt. [MERGED] If you don't care about this, add machdep.hyperthreading_allowed="1" to /boot/loader.conf and reboot. > One other thing is when I try to switch off hyperthreading in BIOS, it > will hang at bootup when it are settling the scsi drives. After awhile it > will give me scsi timeouts. This only happens when I have two cpu enabled > and hyperthreading off. If I disable one cpu w ht off it will boot wo > problems, or two cpus w ht. But booting with ht + two cpu's gives me the > other problem. Sounds like the BIOS is not rerouting the interrupts correctly. Check for a BIOS update. -- Doug White | FreeBSD: The Power to Serve dwhite@gumbysoft.com | www.FreeBSD.org