From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751830AbcF0HAB (ORCPT ); Mon, 27 Jun 2016 03:00:01 -0400 Received: from verein.lst.de ([213.95.11.211]:43226 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750870AbcF0HAA (ORCPT ); Mon, 27 Jun 2016 03:00:00 -0400 Date: Mon, 27 Jun 2016 08:59:49 +0200 From: Torsten Duwe To: Pavel Machek Cc: Jiri Kosina , Miroslav Benes , Josh Poimboeuf , matz@suse.de, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Disable non-ABI-compliant optimisations for live patching Message-ID: <20160627065949.GA3399@lst.de> References: <20160622142441.GA31609@lst.de> <20160622151911.7dgacgsgbcjopopz@treble> <20160623100550.GB31609@lst.de> <20160626223956.GD21026@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160626223956.GD21026@amd> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 27, 2016 at 12:39:56AM +0200, Pavel Machek wrote: > Would it be possible to document which kind of guarantees live > patching needs from compiler? Sure, here you go, all required guarantees: Stick to the ABI. > I always assumed that whoever is preparing the patch does manual > investigation to see what needs to be changed and how, but apparantly > that's not the case, so documentation would be good. See above for the documentation. Imagine each architecture had a whole hand-optimised assembler kernel. That would give some performance improvement, right? Same issue here, only much smaller. It's ultimate performance vs. maintainability. HTH, Torsten