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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 3E257C43441 for ; Thu, 15 Nov 2018 05:59:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 102642087E for ; Thu, 15 Nov 2018 05:59:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 102642087E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728480AbeKOQF0 (ORCPT ); Thu, 15 Nov 2018 11:05:26 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35856 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726574AbeKOQF0 (ORCPT ); Thu, 15 Nov 2018 11:05:26 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2622E308426A; Thu, 15 Nov 2018 05:59:00 +0000 (UTC) Received: from dhcp-128-65.nay.redhat.com (ovpn-12-146.pek2.redhat.com [10.72.12.146]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 99D8C1019628; Thu, 15 Nov 2018 05:58:56 +0000 (UTC) Date: Thu, 15 Nov 2018 13:58:53 +0800 From: Dave Young To: lijiang Cc: Borislav Petkov , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org, bhe@redhat.com Subject: Re: [PATCH 1/2 v6] x86/kexec_file: add e820 entry in case e820 type string matches to io resource name Message-ID: <20181115055853.GA4445@dhcp-128-65.nay.redhat.com> References: <20181114072926.13312-1-lijiang@redhat.com> <20181114072926.13312-2-lijiang@redhat.com> <20181114112600.GD13926@zn.tnic> <9eb61523-7a08-24c4-ac15-050537bd9203@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9eb61523-7a08-24c4-ac15-050537bd9203@redhat.com> User-Agent: Mutt/1.9.5 (2018-04-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Thu, 15 Nov 2018 05:59:00 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/15/18 at 01:44pm, lijiang wrote: > 在 2018年11月14日 19:26, Borislav Petkov 写道: > > On Wed, Nov 14, 2018 at 03:29:25PM +0800, Lianbo Jiang wrote: > >> When load the kernel image and initramfs by kexec_file_load syscall, it can > >> not add exact e820 reserved type to kdump kernel e820 table. > >> > >> Kdump uses walk_iomem_res_desc() to iterate io resources, then adds matched > >> desc to e820 table for kdump kernel. But, when convert the e820 type into > >> the iores descriptors, several e820 types are converted to 'IORES_DES_NONE' > >> in this function e820_type_to_iores_desc(). So the walk_iomem_res_desc() > >> will get these unnecessary types(E820_TYPE_RAM/E820_TYPE_UNUSABLE/E820_TYPE > >> _KERN) when iterate io resources by the 'IORES_DES_NONE'. > >> > >> It needs filter out these redundant type(such as E820_TYPE_RAM/E820_TYPE_ > >> UNUSABLE/E820_TYPE_KERN) in order to add exact e820 reserved type to kdump > >> kernel e820 table. Thus it also needs an extra checking in memmap_entry_ > >> callback() to match the e820 type and resource name. > > > > Ok, it took me a while to parse what this is trying to say so let's > > start from the top: > > > > * What resource type do you do need in the second kernel? > > > > Thanks for your comment. > > The e820 reserved ranges need to be passed to the second kernel. > > > * The most important question: why? > > > > At present, the upstream kernel does not pass the e820 reserved ranges to the > second kernel, which might cause two problems: > > The first one is the MMCONFIG issue, the PCI MMCONFIG(extended mode) requires > the reserved region otherwise it falls back to legacy mode, which might lead to > the hot-plug device could not be recognized in kdump kernel. > > Another one is that the e820 reserved ranges do not setup in kdump kernel, which > could cause kdump can't work in some machines. To know more information, please > refer to the [PATCH 2/2 v6] patch log. > > > > * If it is the reserved resource, why aren't you adding > > IORES_DESC_RESERVED or so which to look for instead of this hacky string > > comparison? > > > > Adding the new descriptor 'IORES_DESC_RESERVED' is also a good solution. I will I was not sure if something else depends on IORES_DESC_NONE and if it is easy to split it and add IORES_DESC_RESERVED But if you can prove it is safe then it would be a better way. Thanks Dave