Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262764AbUCRRBh (ORCPT ); Thu, 18 Mar 2004 12:01:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262766AbUCRRBh (ORCPT ); Thu, 18 Mar 2004 12:01:37 -0500 Received: from chaos.analogic.com ([204.178.40.224]:19854 "EHLO chaos.analogic.com") by vger.kernel.org with ESMTP id S262764AbUCRRBe (ORCPT ); Thu, 18 Mar 2004 12:01:34 -0500 Date: Thu, 18 Mar 2004 11:59:55 -0500 (EST) From: "Richard B. Johnson" X-X-Sender: root@chaos Reply-To: root@chaos.analogic.com To: Justin Piszcz cc: linux-kernel@vger.kernel.org Subject: Re: Linux Kernel Microcode Question In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1630 Lines: 51 On Thu, 18 Mar 2004, Justin Piszcz wrote: [SNIPPED...] > > My question is, what are the advantages vs disadvantages in updating your > CPU's microcode? > > Is it worth it? Remember the CPU with the f00f bug? How about the FP unit bug? With ucode updates, those bugs can be fixed with zero overhead, just an additional second or two of boot-time. > > Does it matter what type of Intel CPU you have? > Of course, some don't have WCS (Writable control-store) and therefore can't be updated. > Do some CPU's benefit more than others for microcode updates? > Only the broken ones. > > Can anyone explain reasons to or not to update the CPU microcode? > "If it ain't broke, don't fix it.".... But there are some people who want the "latest and greatest" even though there is no performance change at all. When new CPUs hit the market there are some "immature features", i.e., BUGS. With a WCS, micro-code work-arounds can be provided so that the CPU doesn't have to be thrown away. If you use the wrong micro- code, perhaps the "latest and greatest", you may actually break the CPU because the work-arounds go away. Review the stuff on http://www.x86.org. Even though it's slanted far to the left, there is some good information there. Cheers, Dick Johnson Penguin : Linux version 2.4.24 on an i686 machine (797.90 BogoMips). Note 96.31% of all statistics are fiction. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/