From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752063AbcHHIQL (ORCPT ); Mon, 8 Aug 2016 04:16:11 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:10651 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751670AbcHHIQJ (ORCPT ); Mon, 8 Aug 2016 04:16:09 -0400 X-IBM-Helo: d28dlp01.in.ibm.com X-IBM-MailFrom: hbathini@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org Subject: Re: [RESEND][PATCH v2 2/2] powerpc/fadump: parse fadump reserve memory size based on memory range To: Michael Ellerman , rusty@rustcorp.com.au, ebiederm@xmission.com, vgoyal@redhat.com, linuxppc-dev References: <147025270324.29229.8322429758761407397.stgit@hbathini.in.ibm.com> <147025281599.29229.9962999599360876220.stgit@hbathini.in.ibm.com> <87h9b0g953.fsf@concordia.ellerman.id.au> Cc: Mahesh J Salgaonkar , kexec@lists.infradead.org, lkml , Ananth N Mavinakayanahalli From: Hari Bathini Date: Mon, 8 Aug 2016 13:45:50 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16080808-0012-0000-0000-000002DC3961 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16080808-0013-0000-0000-00000E322018 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-08-08_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1608080099 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday 05 August 2016 12:23 AM, Hari Bathini wrote: > > On Thursday 04 August 2016 03:15 PM, Michael Ellerman wrote: >> Hari Bathini writes: >> ... >>> /** >>> * fadump_calculate_reserve_size(): reserve variable boot area 5% >>> of System RAM >>> * >>> @@ -212,12 +262,17 @@ static inline unsigned long >>> fadump_calculate_reserve_size(void) >>> { >>> unsigned long size; >>> + /* sets fw_dump.reserve_bootvar */ >>> + parse_fadump_reserve_mem(); >>> + >>> /* >>> * Check if the size is specified through fadump_reserve_mem= >>> cmdline >>> * option. If yes, then use that. >>> */ >>> if (fw_dump.reserve_bootvar) >>> return fw_dump.reserve_bootvar; >>> + else >>> + printk(KERN_INFO "fadump: calculating default boot size\n"); >>> /* divide by 20 to get 5% of value */ >>> size = memblock_end_of_DRAM() / 20; >> The code already knows how to reserve 5% based on the size of the >> machine's >> memory, as long as no commandline parameter is passed. So why can't we >> just use that logic? > > Hi Michael, > > That is the default value reserved but not a good enough value for > every case. It is a bit difficult to come up with a robust formula > that works for every case as new kernel changes could make the > values obsolete. But it won't be all that difficult to find values that > work for different memory ranges for a given kernel version. > Passing that as range based input with "fadump_reserve_mem" > parameter would work for every memory configuration on a > given system, which is what this patch is trying to provide.. > Hi Michael, You want me to add this to the changelog on respin? Thanks Hari > Thanks > Hari > > >> cheers >> >