From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755369AbaIDUWU (ORCPT ); Thu, 4 Sep 2014 16:22:20 -0400 Received: from terminus.zytor.com ([198.137.202.10]:37905 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755202AbaIDUWT (ORCPT ); Thu, 4 Sep 2014 16:22:19 -0400 Message-ID: <5408C9C4.1010705@zytor.com> Date: Thu, 04 Sep 2014 13:21:24 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 MIME-Version: 1.0 To: Henrique de Moraes Holschuh , Toshi Kani CC: tglx@linutronix.de, mingo@redhat.com, akpm@linuxfoundation.org, arnd@arndb.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, jgross@suse.com, stefan.bader@canonical.com, luto@amacapital.net, konrad.wilk@oracle.com Subject: Re: [PATCH 1/5] x86, mm, pat: Set WT to PA4 slot of PAT MSR References: <1409855739-8985-1-git-send-email-toshi.kani@hp.com> <1409855739-8985-2-git-send-email-toshi.kani@hp.com> <20140904201123.GA9116@khazad-dum.debian.net> In-Reply-To: <20140904201123.GA9116@khazad-dum.debian.net> 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 09/04/2014 01:11 PM, Henrique de Moraes Holschuh wrote: > > I am worried of uncharted territory, here. I'd actually advocate for not > enabling the upper four PAT entries on IA-32 at all, unless Windows 9X / XP > is using them as well. Is this a real concern, or am I being overly > cautious? > It is extremely unlikely that we'd have PAT issues in 32-bit mode and not in 64-bit mode on the same CPU. As far as I know, the current blacklist rule is very conservative due to lack of testing more than anything else. -hpa