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_HELO_NONE,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 E186AC282CE for ; Thu, 23 May 2019 03:15:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9DC9E2173C for ; Thu, 23 May 2019 03:15:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729655AbfEWDP6 (ORCPT ); Wed, 22 May 2019 23:15:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47484 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728734AbfEWDP5 (ORCPT ); Wed, 22 May 2019 23:15:57 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 55C983092650; Thu, 23 May 2019 03:15:52 +0000 (UTC) Received: from localhost (ovpn-12-100.pek2.redhat.com [10.72.12.100]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AF0AB19C4F; Thu, 23 May 2019 03:15:48 +0000 (UTC) Date: Thu, 23 May 2019 11:15:41 +0800 From: Baoquan He To: Dave Young Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@kernel.org, bp@alien8.de, hpa@zytor.com, kirill.shutemov@linux.intel.com, x86@kernel.org Subject: Re: [PATCH v4 3/3] x86/kdump/64: Change the upper limit of crashkernel reservation Message-ID: <20190523031541.GD3805@MiWiFi-R3L-srv> References: <20190509013644.1246-1-bhe@redhat.com> <20190509013644.1246-4-bhe@redhat.com> <20190522031133.GA31269@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190522031133.GA31269@dhcp-128-65.nay.redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Thu, 23 May 2019 03:15:57 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/22/19 at 11:11am, Dave Young wrote: > > /* > > - * Keep the crash kernel below this limit. On 32 bits earlier kernels > > - * would limit the kernel to the low 512 MiB due to mapping restrictions. > > + * Keep the crash kernel below this limit. > > + * > > + * On 32 bits earlier kernels would limit the kernel to the low > > + * 512 MiB due to mapping restrictions. > > + * > > + * On 64bit, old kexec-tools need to be under 896MiB. The later > > + * supports to put kernel above 4G, up to system RAM top. Here > > Above two lines are not reflected in code because we have removed > the 896M limitation, it would be better to drop the two lines to > avoid confusion. Missed these comments at bottom of mail. Yes, will remove these two lines. > > > + * kdump kernel need be restricted to be under 64TB, which is > > + * the upper limit of system RAM in 4-level paing mode. Since > > + * the kdump jumping could be from 5-level to 4-level, the jumping > > + * will fail if kernel is put above 64TB, and there's no way to > > + * detect the paging mode of the kernel which will be loaded for > > + * dumping during the 1st kernel bootup. > > */ > > #ifdef CONFIG_X86_32 > > # define CRASH_ADDR_LOW_MAX SZ_512M > > # define CRASH_ADDR_HIGH_MAX SZ_512M > > #else > > # define CRASH_ADDR_LOW_MAX SZ_4G > > -# define CRASH_ADDR_HIGH_MAX MAXMEM > > +# define CRASH_ADDR_HIGH_MAX (64UL << 40) > > Maybe add a new macro in sizes.h like SZ_64T I am fine, will add and use it here. Thanks.