From owner-freebsd-current@FreeBSD.ORG Fri Sep 16 14:13:01 2011 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7C8A5106566C; Fri, 16 Sep 2011 14:13:01 +0000 (UTC) (envelope-from aboyer@averesystems.com) Received: from zimbra.averesystems.com (75-149-8-245-Pennsylvania.hfc.comcastbusiness.net [75.149.8.245]) by mx1.freebsd.org (Postfix) with ESMTP id 49C2B8FC0C; Fri, 16 Sep 2011 14:13:01 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by zimbra.averesystems.com (Postfix) with ESMTP id EE0AE8BC025; Fri, 16 Sep 2011 10:15:40 -0400 (EDT) X-Virus-Scanned: amavisd-new at averesystems.com Received: from zimbra.averesystems.com ([127.0.0.1]) by localhost (zimbra.averesystems.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id IljzxD1KS5yf; Fri, 16 Sep 2011 10:15:39 -0400 (EDT) Received: from riven.arriad.com (fw.arriad.com [10.0.0.16]) by zimbra.averesystems.com (Postfix) with ESMTPSA id F3BAD8BC024; Fri, 16 Sep 2011 10:15:38 -0400 (EDT) Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=us-ascii From: Andrew Boyer In-Reply-To: <201109160807.04617.jhb@freebsd.org> Date: Fri, 16 Sep 2011 10:12:57 -0400 Content-Transfer-Encoding: quoted-printable Message-Id: <8C685A3B-F7E3-4F4B-87D4-56B8E9CE9FC1@averesystems.com> References: <2C3C4570-C5F9-42F5-AA81-900151590DB8@averesystems.com> <4E7106DE.40707@FreeBSD.org> <70B018CB-4658-45DD-929E-A953B299E737@averesystems.com> <201109160807.04617.jhb@freebsd.org> To: John Baldwin X-Mailer: Apple Mail (2.1084) Cc: freebsd-current@freebsd.org, Andriy Gapon Subject: Re: Identification of HTT cores on newer (CPUID leaf 11) Intel processors X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Sep 2011 14:13:01 -0000 On Sep 16, 2011, at 8:07 AM, John Baldwin wrote: > I think the "right" way for an admin to disable HTT is to disable it = in the > BIOS so that it doesn't show up in the MADT. Back when we were doing = the > MPTABLE_FORCE_HTT hack having a separate tunable made sense (and it = possibly > made some limited sense if you were worried about the vulnerability on = running > machines). However, at this point I think the tunable should just go = away and > admins should configure HTT on or off in the BIOS like they would for = any > other OS. >=20 > --=20 > John Baldwin To do it this way (leave SMT enabled in the BIOS but disabled in the OS) = makes it easier to release a future upgrade to take advantage of those = cores. Once systems are distributed to customer sites it becomes very = difficult to do BIOS maintenance. -Andrew -------------------------------------------------- Andrew Boyer aboyer@averesystems.com