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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 6D9DDCA9EB6 for ; Wed, 23 Oct 2019 07:43:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 35D802064A for ; Wed, 23 Oct 2019 07:43:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="cdEy3TTo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389990AbfJWHnX (ORCPT ); Wed, 23 Oct 2019 03:43:23 -0400 Received: from mail.skyhub.de ([5.9.137.197]:55148 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389298AbfJWHnW (ORCPT ); Wed, 23 Oct 2019 03:43:22 -0400 Received: from zn.tnic (p200300EC2F11E8005961F1FA34C94581.dip0.t-ipconnect.de [IPv6:2003:ec:2f11:e800:5961:f1fa:34c9:4581]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id A9B5D1EC0C97; Wed, 23 Oct 2019 09:43:21 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1571816601; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=jTCcCEyTWzLsA6PZt0F/iewZdpPjA6PgMOIuBrdzh3I=; b=cdEy3TToYVeoDXvYhfp+VeBQPjb9VRyyz6QpXjK783pWJfrUP0z4le2zjQGLZeomi4SP9v b+PUlvkkKoHXtvxtNGkCULnMrZJ5Hfpug6PA3jsOHLKTpSFaX2JLJIQOu7Sbo6B1Q3rUR3 00q04azm4SlI3Jp3T0JjVWpel658k+k= Date: Wed, 23 Oct 2019 09:43:16 +0200 From: Borislav Petkov To: lijiang Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, bhe@redhat.com, dyoung@redhat.com, jgross@suse.com, dhowells@redhat.com, Thomas.Lendacky@amd.com, ebiederm@xmission.com, vgoyal@redhat.com, kexec@lists.infradead.org Subject: Re: [PATCH 1/3 v4] x86/kdump: always reserve the low 1MiB when the crashkernel option is specified Message-ID: <20191023074316.GA16060@zn.tnic> References: <20191017094347.20327-1-lijiang@redhat.com> <20191017094347.20327-2-lijiang@redhat.com> <20191022083015.GB31700@zn.tnic> <0e657965-6f97-84ce-e51d-42d4978c4d88@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <0e657965-6f97-84ce-e51d-42d4978c4d88@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 23, 2019 at 01:23:33PM +0800, lijiang wrote: > Kdump kernel will reuse the first 640k region because the real mode > trampoline has to work in this area. When the vmcore is dumped, the > old memory in this area may be accessed, therefore, kernel has to > copy the contents of the first 640k area to a backup region so that > kdump kernel can read the old memory from the backup area of the > first 640k area, which is done in the purgatory(). That sounds better. :) -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette