From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755209Ab0IHVFX (ORCPT ); Wed, 8 Sep 2010 17:05:23 -0400 Received: from terminus.zytor.com ([198.137.202.10]:53203 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754359Ab0IHVFR (ORCPT ); Wed, 8 Sep 2010 17:05:17 -0400 Message-ID: <4C87FA80.9080100@zytor.com> Date: Wed, 08 Sep 2010 14:05:04 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.8) Gecko/20100806 Fedora/3.1.2-1.fc13 Thunderbird/3.1.2 MIME-Version: 1.0 To: Alan Cox CC: Nick Lowe , Hans-Peter Jansen , linux-kernel@vger.kernel.org Subject: Re: AMD Geode NOPL emulation for kernel 2.6.36-rc2 References: <55BC9463-95B9-4034-AA1E-55042D6E9354@gmail.com> <201009081115.15544.hpj@urpla.net> <20100908185605.55671889@lxorguk.ukuu.org.uk> <20100908200715.2e56d0be@lxorguk.ukuu.org.uk> <20100908221144.73066e2d@lxorguk.ukuu.org.uk> In-Reply-To: <20100908221144.73066e2d@lxorguk.ukuu.org.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/08/2010 02:11 PM, Alan Cox wrote: > > Getting the stuff right in the current kernel makes it easier to backport > and fix and do tidily. It's not as if NOPL is complicated to emulate. The execution phase is easy ;) The parsing phase is rather hard. This is part of why I would much rather see a single x86 interpreter in the kernel, and the one single interpreter that we need anyway is the one in KVM. I haven't looked at what it would take to generalize it to also support trap and emulate of arbitrary instructions (not just NOPL and CMOV and so on), but x86 is subtle and quick to anger, and doing it wrong can trivially introduce security holes. -hpa