From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id BA0B17D089 for ; Wed, 5 Dec 2018 10:17:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727309AbeLEKRC (ORCPT ); Wed, 5 Dec 2018 05:17:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45960 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726889AbeLEKRC (ORCPT ); Wed, 5 Dec 2018 05:17:02 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B2D36307D84C; Wed, 5 Dec 2018 10:17:01 +0000 (UTC) Received: from dhcp-128-65.nay.redhat.com (ovpn-12-63.pek2.redhat.com [10.72.12.63]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1BC195FC05; Wed, 5 Dec 2018 10:16:56 +0000 (UTC) Date: Wed, 5 Dec 2018 18:16:53 +0800 From: Dave Young To: lijiang Cc: Borislav Petkov , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, akpm@linux-foundation.org, bhe@redhat.com, Jonathan Corbet , linux-doc@vger.kernel.org, Kazuhito Hagio Subject: Re: [PATCH 1/2 v2] kdump: add the vmcoreinfo documentation Message-ID: <20181205101653.GA6940@dhcp-128-65.nay.redhat.com> References: <20181202030839.29945-1-lijiang@redhat.com> <20181202030839.29945-2-lijiang@redhat.com> <20181203150809.GA4794@zn.tnic> <779dbae7-f6e2-e9e4-bdd0-0a9e6ec62487@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <779dbae7-f6e2-e9e4-bdd0-0a9e6ec62487@redhat.com> User-Agent: Mutt/1.9.5 (2018-04-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Wed, 05 Dec 2018 10:17:01 +0000 (UTC) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org > >> +init_uts_ns > >> +=========== > >> +This is the UTS namespace, which is used to isolate two specific elements > >> +of the system that relate to the uname system call. The UTS namespace is > >> +named after the data structure used to store information returned by the > >> +uname system call. > > > > Those non-obvious exports should also have a short explanation why > > they're part of VMCOREINFO. > > > >> + > >> +node_online_map > >> +=============== > >> +It is a macro definition, actually it is an arrary node_states[N_ONLINE], > >> +and it represents the set of online node in a system, one bit position > >> +per node number. > > > > Ditto. > > > > So yeah, people can find out what those things are but I think it is > > more important to state here *why* they're part of VMCOREINFO and how > > they're used and why they're exported. > > > > This is a good question. > > For these two *why*, it should be easy to understand. Because user-space tools > need to know basic information, such as the symbol values, field offset, structure > size, etc. Otherwise, these tools won't know how to analyze the memory of the crash > kernel. > > For the second question 'how they are used', we can get the answer from user-space > tools, such as makedumpfile, crash tools. Therefore, it may not need to explain any > more in kernel document. On the other hand, if we must put these contents into kernel > document, i have to say, that would be a hard task. It should be a good chance to learn how makedumpfile works :), Maybe it is hard to get *all* of them, but it would be good to dig and find the thing you can find then explain it. And leave those *unknown* part as FIXME or TODO, people can add description later. Added Kazu in cc as well.. Thanks Dave