From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 910A3C48BC2 for ; Sun, 27 Jun 2021 19:23:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 619A561C2F for ; Sun, 27 Jun 2021 19:23:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231484AbhF0TWg (ORCPT ); Sun, 27 Jun 2021 15:22:36 -0400 Received: from hosting.gsystem.sk ([212.5.213.30]:57208 "EHLO hosting.gsystem.sk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231447AbhF0TWf (ORCPT ); Sun, 27 Jun 2021 15:22:35 -0400 Received: from [192.168.0.2] (188-167-68-178.dynamic.chello.sk [188.167.68.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by hosting.gsystem.sk (Postfix) with ESMTPSA id 9A4607A027B; Sun, 27 Jun 2021 21:20:09 +0200 (CEST) From: Ondrej Zary To: Marcos Del Sol Vives Subject: Re: [PATCH v3] x86: add NOPL and CMOV emulation Date: Sun, 27 Jun 2021 21:20:06 +0200 User-Agent: KMail/1.9.10 Cc: x86@kernel.org, linux-kernel@vger.kernel.org References: <20210626130313.1283485-1-marcos@orca.pet> In-Reply-To: <20210626130313.1283485-1-marcos@orca.pet> X-KMail-QuotePrefix: > MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <202106272120.07140.linux@zary.sk> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Saturday 26 June 2021 15:03:14 Marcos Del Sol Vives wrote: > NOPL and CMOV are a set of instructions that were introduced to the > x86 architecture with the i686 ISA in 1995, first implemented in the > Intel Pentium Pro and Pentium II processors. > > While virtually all desktop and server systems are modern enough to > support these instructions, in the embedded market things are a little > bit different: DM&P is still manufacturing their i586-only Vortex86 > SoCs, and many embedded devices still in use are stuck on legacy SoCs > that either are i586-only (AMD Elan, AMD Geode GX1) or implement i686 > but lack the NOPL instructions (Transmeta devices, AMD Geode LX). > > This is a problem because most modern Linux distributions, such as > Debian and all its derivatives, have started compiling targeting i686, > leaving old embedded devices using binary distributions without an > easy upgrade path. > > This ultimately results in most of these embedded devices running > years old, insecure and obsolete installations, and this itself can be > seen on the DM&P's own supported OS page where the newest supported > desktop Linux distro is Ubuntu 18.04, already three years old. > > The emulation of these instructions thus allow upgrading to newer > distributions just by replacing the kernel, keeping all precompiled > binaries intact. Great, this would allow me to update my old Pentium 133 box from unsupported Debian 8 to 9, 10 and even the upcoming 11. -- Ondrej Zary