From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752793AbdECIud (ORCPT ); Wed, 3 May 2017 04:50:33 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:54812 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752385AbdECIuX (ORCPT ); Wed, 3 May 2017 04:50:23 -0400 Subject: Re: [PATCH v4 RFT 1/2] powerpc/fadump: reduce memory consumption for capture kernel To: Michal Suchanek , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Jonathan Corbet , Vlastimil Babka , Michal Hocko , linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20170502155611.6789-1-msuchanek@suse.de> <765ca86f-b6c5-190e-b3a9-91282e199baf@linux.vnet.ibm.com> From: Hari Bathini Date: Wed, 3 May 2017 14:19:19 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <765ca86f-b6c5-190e-b3a9-91282e199baf@linux.vnet.ibm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable x-cbid: 17050308-0004-0000-0000-000001FDB1A6 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17050308-0005-0000-0000-000009F297C4 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-03_07:,, 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=8.0.1-1703280000 definitions=main-1705030169 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 03 May 2017 12:43 PM, Hari Bathini wrote: > > > On Tuesday 02 May 2017 09:26 PM, Michal Suchanek wrote: >> With fadump (dump capture) kernel booting like a regular kernel, it >> almost >> needs the same amount of memory to boot as the production kernel, >> which is >> unwarranted for a dump capture kernel. But with no option to disable >> some >> of the unnecessary subsystems in fadump kernel, that much memory is >> wasted >> on fadump, depriving the production kernel of that memory. >> >> Introduce kernel parameter 'fadump_append=' that would take regular >> kernel >> parameters to be appended when fadump is active. >> This 'fadump_append=' parameter can be leveraged to pass parameters like >> nr_cpus=1, cgroup_disable=memory and numa=off, to disable unwarranted >> resources/subsystems. >> >> Also, ensure the log "Firmware-assisted dump is active" is printed early >> in the boot process to put the subsequent fadump messages in context. >> >> Suggested-by: Michael Ellerman >> Signed-off-by: Hari Bathini >> Signed-off-by: Michal Suchanek >> --- >> v4: >> - use space separated arguments instead of comma separated >> - do not append parameters when fadummp is disabled >> --- >> arch/powerpc/kernel/fadump.c | 27 ++++++++++++++++++++++++--- >> 1 file changed, 24 insertions(+), 3 deletions(-) >> >> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c >> index ebf2e9c..e0c728a 100644 >> --- a/arch/powerpc/kernel/fadump.c >> +++ b/arch/powerpc/kernel/fadump.c >> @@ -79,8 +79,10 @@ int __init early_init_dt_scan_fw_dump(unsigned >> long node, >> * dump data waiting for us. >> */ >> fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump", NULL); >> - if (fdm_active) >> + if (fdm_active) { >> + pr_info("Firmware-assisted dump is active.\n"); >> fw_dump.dump_active = 1; >> + } >> >> /* Get the sizes required to store dump data for the firmware >> provided >> * dump sections. >> @@ -263,8 +265,12 @@ int __init fadump_reserve_mem(void) >> { >> unsigned long base, size, memory_boundary; >> >> - if (!fw_dump.fadump_enabled) >> + if (!fw_dump.fadump_enabled) { >> + if (fw_dump.dump_active) >> + pr_warn("Firmware-assisted dump was active but kernel" >> + " booted with fadump disabled!\n"); >> return 0; >> + } >> >> if (!fw_dump.fadump_supported) { >> printk(KERN_INFO "Firmware-assisted dump is not supported on" >> @@ -304,7 +310,6 @@ int __init fadump_reserve_mem(void) >> memory_boundary = memblock_end_of_DRAM(); >> >> if (fw_dump.dump_active) { >> - printk(KERN_INFO "Firmware-assisted dump is active.\n"); >> /* >> * If last boot has crashed then reserve all the memory >> * above boot_memory_size so that we don't touch it until >> @@ -363,6 +368,22 @@ unsigned long __init >> arch_reserved_kernel_pages(void) >> return memblock_reserved_size() / PAGE_SIZE; >> } >> >> +/* Look for fadump_append= cmdline option. */ >> +static int __init early_fadump_append_param(char *p) >> +{ >> + if (!p) >> + return 1; >> + >> + if (fw_dump.fadump_enabled && fw_dump.dump_active) { >> + pr_info("enforcing additional parameters (%s) passed through " >> + "'fadump_append=' parameter\n", p); >> + parse_early_options(p); > > While testing this on a system with yaboot bootloader, it seems that > parsing > a parameter with syntax like fadump_append="nr_cpus numa=off" is not fadump_append="nr_cpus numa=off" should have read fadump_append="nr_cpus=1 numa=off". Nonetheless, considering different environments this is supposed to work, I was trying to convey comma-separated append list maybe better over space-separated one.. Thanks Hari