Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752757AbaAQQX4 (ORCPT ); Fri, 17 Jan 2014 11:23:56 -0500 Received: from terminus.zytor.com ([198.137.202.10]:56776 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751354AbaAQQXx (ORCPT ); Fri, 17 Jan 2014 11:23:53 -0500 Message-ID: <52D958FC.9020700@zytor.com> Date: Fri, 17 Jan 2014 08:23:24 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Borislav Petkov , Henrique de Moraes Holschuh CC: Aravind Gopalakrishnan , X86 ML , LKML , Kim Naru , Sherry Hurwitz Subject: Re: [PATCH] x86, CPU, AMD: Add workaround for family 16h, erratum 793 References: <20140114114133.GA31473@khazad-dum.debian.net> <20140114115547.GA29887@pd.tnic> <52D55468.6000000@zytor.com> <20140114153534.GE29865@pd.tnic> <20140114162722.GF29865@pd.tnic> <52D59ACC.3090100@amd.com> <20140114203848.GP29865@pd.tnic> <52D81DB5.7000608@amd.com> <20140117002123.GA9165@khazad-dum.debian.net> <20140117101842.GB8715@pd.tnic> In-Reply-To: <20140117101842.GB8715@pd.tnic> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/17/2014 02:18 AM, Borislav Petkov wrote: > > We also cannot carry *every* erratum workaround in the kernel just > because people don't update firmware. Firmware is becoming ubiquitous, > sadly, and because of that, admins should provision for firmware > upgrades too. > > Besides, *even* if we put *all* errata fixes in the kernel, you'd need > to update it anyway and reboot. In this case, you can just as well > update your firmware instead, which involves that same reboot. > Actually I by and large disagree with that. There is a limit, of course, but when it comes to flipping an MSR in init code, the bar is pretty darn low. We have quirks for all kind of hardware, and this is just another example. What *is* important, though, is that the workaround is well commented so that when someone comes and wonders "WTF is this, and what constraints does it have on it" they can get back to the primary sources (errata documents, mailing list discussions, CVEs, etc.) without undue effort. The effort of a kernel update is much lower, especially since the kernel is generally automatically updated. It would be awesome if that was done for firmware, but in the absence of central distribution, arbitrary EOL sunsets, and a standard OS-driven firmware installer, it just isn't going to happen widely. Yes, that is a problem. -hpa -- 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/