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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 A9AE7C433FF for ; Tue, 13 Aug 2019 13:43:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8392520679 for ; Tue, 13 Aug 2019 13:43:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729261AbfHMNnS (ORCPT ); Tue, 13 Aug 2019 09:43:18 -0400 Received: from mx2.suse.de ([195.135.220.15]:58534 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728338AbfHMNnR (ORCPT ); Tue, 13 Aug 2019 09:43:17 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 6AF5EAD05; Tue, 13 Aug 2019 13:43:16 +0000 (UTC) Date: Tue, 13 Aug 2019 15:43:11 +0200 (CEST) From: Miroslav Benes To: Petr Mladek cc: Jiri Kosina , Josh Poimboeuf , Joe Lawrence , Kamalesh Babulal , Nicolai Stange , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 4/5] livepatch: Documentation of the new API for tracking system state changes In-Reply-To: <20190719074034.29761-5-pmladek@suse.com> Message-ID: References: <20190719074034.29761-1-pmladek@suse.com> <20190719074034.29761-5-pmladek@suse.com> User-Agent: Alpine 2.21 (LSU 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 19 Jul 2019, Petr Mladek wrote: > Documentation explaining the motivation, capabilities, and usage > of the new API for tracking system state changes. > > Signed-off-by: Petr Mladek > --- > Documentation/livepatch/index.rst | 1 + > Documentation/livepatch/system-state.rst | 167 +++++++++++++++++++++++++++++++ > 2 files changed, 168 insertions(+) > create mode 100644 Documentation/livepatch/system-state.rst > > diff --git a/Documentation/livepatch/index.rst b/Documentation/livepatch/index.rst > index edd291d51847..94bbbc2c8993 100644 > --- a/Documentation/livepatch/index.rst > +++ b/Documentation/livepatch/index.rst > @@ -9,6 +9,7 @@ Kernel Livepatching > > livepatch > callbacks > + system-state > cumulative-patches > module-elf-format > shadow-vars This is really a nitpick, but wouldn't it be better to move system-state to the end of the list, because it relies on the information from the other parts? > diff --git a/Documentation/livepatch/system-state.rst b/Documentation/livepatch/system-state.rst > new file mode 100644 > index 000000000000..f04ef2b9089a > --- /dev/null > +++ b/Documentation/livepatch/system-state.rst > @@ -0,0 +1,167 @@ > +==================== > +System State Changes > +==================== > + > +Some users are really reluctant to reboot a system. This brings the need > +to provide more livepatches and maintain some compatibility between them. > + > +Maintaining more livepatches is much easier with cumulative livepatches. > +Each new livepatch completely replaces any older one. It can keep, > +add, and even remove fixes. And it is typically safe to replace any version > +of the livepatch with any other one thanks to the atomic replace feature. > + > +The problems might come with shadow variables and callbacks. They might > +change the system behavior or state so that it is not longer safe to s/not longer/no longer/ (there are more instances of this in the patch). Miroslav