From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754914Ab2CJD1v (ORCPT ); Fri, 9 Mar 2012 22:27:51 -0500 Received: from mail-pz0-f46.google.com ([209.85.210.46]:34825 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752166Ab2CJD1t (ORCPT ); Fri, 9 Mar 2012 22:27:49 -0500 Message-ID: <4F5ACA2D.5000000@gmail.com> Date: Sat, 10 Mar 2012 11:27:41 +0800 From: Cong Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120216 Thunderbird/10.0.1 MIME-Version: 1.0 To: Dave Young CC: linux-kernel@vger.kernel.org, x86@kernel.org, linux@arm.linux.org.uk, vgoyal@redhat.com Subject: Re: [PATCH] kdump x86: fix total mem size calculation for reservation References: <20120309083009.GA14067@darkstar.nay.redhat.com> In-Reply-To: <20120309083009.GA14067@darkstar.nay.redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/09/2012 04:30 PM, Dave Young wrote: > crashkernel reservation need know the total memory size. Current get_total_mem > simply use max_pfn - min_low_pfn. It is wrong because it will including > memory holes in the middle. > > Especially for kvm guest with memory> 0xe0000000, there's below in qemu code: > qemu split memory as below: > if (ram_size>= 0xe0000000 ) { > above_4g_mem_size = ram_size - 0xe0000000; > below_4g_mem_size = 0xe0000000; > } else { > below_4g_mem_size = ram_size; > } > So for 4G mem guest, seabios will insert a 512M usable region beyond of 4G. > Thus in above case max_pfn - min_low_pfn will be more than original memsize. > > Fixing this issue by using memblock_phys_mem_size() to get the total memsize. > Makes sense for me! > -static inline unsigned long long get_total_mem(void) > -{ > - unsigned long long total; > - > - total = max_pfn - min_low_pfn; > - printk("hidave: memsize=%llu\n", memblock_phys_mem_size()); This debugging line does not exist... so this patch can't be applied.