From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751977Ab3EAQvj (ORCPT ); Wed, 1 May 2013 12:51:39 -0400 Received: from mga01.intel.com ([192.55.52.88]:2403 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751082Ab3EAQvd (ORCPT ); Wed, 1 May 2013 12:51:33 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,590,1363158000"; d="scan'208";a="330756065" From: Andi Kleen To: "Theodore Ts'o" Cc: Borislav Petkov , Andy Lutomirski , linux-kernel@vger.kernel.org, x86@kernel.org, Andrew Lutomirski , "H. Peter Anvin" Subject: Re: [PATCH v5] x86: Enable fast strings on Intel if BIOS hasn't already References: <3cdeaedaa41e258e8aa9ca83d79a936e0b9462bc.1367385613.git.luto@amacapital.net> <20130501113352.GA29571@pd.tnic> <20130501163404.GA6286@thunk.org> Date: Wed, 01 May 2013 09:51:32 -0700 In-Reply-To: <20130501163404.GA6286@thunk.org> (Theodore Ts'o's message of "Wed, 1 May 2013 12:34:04 -0400") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Theodore Ts'o writes: > > In fact, there is the question of whether we should be checking to see > if the CPU stepping is one of the ones with the bug, and if so, to > have Linux disable fast strings even if the BIOS didn't, instead of > blindly enabling fast strings.... Crossing pages with different memory attributes shouldn't happen in normal operation. I wouldn't be too concerned about that one. I would suggest to leave the bit alone. There may be valid reasons on the system to either set or not set it, which the kernel doesn't necessarily know. -Andi -- ak@linux.intel.com -- Speaking for myself only