From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751615AbdFZJrx (ORCPT ); Mon, 26 Jun 2017 05:47:53 -0400 Received: from mail-wm0-f53.google.com ([74.125.82.53]:33146 "EHLO mail-wm0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751391AbdFZJrm (ORCPT ); Mon, 26 Jun 2017 05:47:42 -0400 Date: Mon, 26 Jun 2017 11:47:38 +0200 From: Ingo Molnar To: Baoquan He Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , "H. Peter Anvin" Subject: Re: [PATCH] x86/boot/KASLR: Skip relocation handling in no kaslr case Message-ID: <20170626094737.d2pzetkhe2sorn6m@gmail.com> References: <1498314309-18502-1-git-send-email-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1498314309-18502-1-git-send-email-bhe@redhat.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Baoquan He wrote: > Kdump kernel will reset to firmware after crash is trigered when > crashkernel=xxM,high is added to kernel command line. Kexec has the > same phenomenon. This only happened on system with kaslr code > compiled in and kernel option 'nokaslr'is added. Both of them works > well when kaslr is enabled. > > When crashkernel high is set or kexec case, kexec/kdump kernel will be > put above 4G. Since we assign the original loading address of kernel to > virt_addr as initial value, the virt_addr will be larger than 1G if kaslr > is disabled, it exceeds the kernel mapping size which is only 1G. Then > it will cause relocation handling error in handle_relocations(). So instead of whacking yet another kexec mole, how could we turn this into a more debuggable warning (either during build or during the failed bootup) instead of a crash and reset (triple fault?) back to the BIOS screen? If kexec/kdump wants to do crazy things they should at least be _debuggable_ in a straightforward manner. Thanks, Ingo