From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) by kanga.kvack.org (Postfix) with ESMTP id C0AA46B0036 for ; Thu, 4 Sep 2014 19:19:40 -0400 (EDT) Received: by mail-pa0-f44.google.com with SMTP id rd3so20848881pab.17 for ; Thu, 04 Sep 2014 16:19:40 -0700 (PDT) Received: from out1-smtp.messagingengine.com (out1-smtp.messagingengine.com. [66.111.4.25]) by mx.google.com with ESMTPS id ad7si584373pbd.81.2014.09.04.16.19.38 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Sep 2014 16:19:39 -0700 (PDT) Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by gateway2.nyi.internal (Postfix) with ESMTP id B31D220825 for ; Thu, 4 Sep 2014 19:19:35 -0400 (EDT) Date: Thu, 4 Sep 2014 20:19:23 -0300 From: Henrique de Moraes Holschuh Subject: Re: [PATCH 1/5] x86, mm, pat: Set WT to PA4 slot of PAT MSR Message-ID: <20140904231923.GA15320@khazad-dum.debian.net> 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> <5408C9C4.1010705@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5408C9C4.1010705@zytor.com> Sender: owner-linux-mm@kvack.org List-ID: To: "H. Peter Anvin" Cc: Toshi Kani , 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 On Thu, 04 Sep 2014, H. Peter Anvin wrote: > 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. Sure, but is it really a good idea to enable this on the *old* non-64-bit capable processors (note: I don't mean x86-64 processors operating in 32-bit mode) ? > As far as I know, the current blacklist rule is very conservative due to > lack of testing more than anything else. I was told that much in 2009 when I asked why cpuid 0x6d8 was blacklisted from using PAT :-) -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org