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Mon, 24 Apr 2023 09:57:24 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E3E0020043; Mon, 24 Apr 2023 09:57:23 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7812720040; Mon, 24 Apr 2023 09:57:23 +0000 (GMT) Received: from [9.101.4.33] (unknown [9.101.4.33]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 24 Apr 2023 09:57:23 +0000 (GMT) Message-ID: Date: Mon, 24 Apr 2023 11:57:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH v10 2/5] powerpc/crash: introduce a new config option CRASH_HOTPLUG Content-Language: en-US To: Sourabh Jain , linuxppc-dev@ozlabs.org, mpe@ellerman.id.au References: <20230423105213.70795-1-sourabhjain@linux.ibm.com> <20230423105213.70795-3-sourabhjain@linux.ibm.com> From: Laurent Dufour In-Reply-To: <20230423105213.70795-3-sourabhjain@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: NDkCLv3pGtdOiEcp1kXvT9kb1eOM7p4K X-Proofpoint-ORIG-GUID: lZ7L_SLh0YoaPcepW8meMTOM5sMdzIX_ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-04-24_06,2023-04-21_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 adultscore=0 mlxlogscore=999 clxscore=1011 mlxscore=0 priorityscore=1501 impostorscore=0 spamscore=0 malwarescore=0 bulkscore=0 phishscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2303200000 definitions=main-2304240085 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230424_025740_477868_69E4AFE9 X-CRM114-Status: GOOD ( 33.69 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: bhe@redhat.com, kexec@lists.infradead.org, Laurent Dufour , eric.devolder@oracle.com, hbathini@linux.ibm.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 23/04/2023 12:52:10, Sourabh Jain wrote: > Due to CPU/Memory hot plug/unplug or online/offline events the system > resources changes. A similar change should reflect in the loaded kdump > kernel kexec segments that describes the state of the CPU and memory of > the running kernel. > > If the kdump kernel kexec segments are not updated after the CPU/Memory > hot plug/unplug or online/offline events and kdump kernel tries to > collect the dump with the stale system resource data then this might > lead to dump collection failure or an inaccurate dump collection. > > The current method to keep the kdump kernel kexec segments up to date is > by reloading the complete kdump kernel whenever a CPU/Memory hot > plug/unplug or online/offline event is observed in userspace. Reloading > the kdump kernel for every CPU/Memory hot plug/unplug or online/offline > event is inefficient and creates a large window where the kdump service > is not available. It can be improved by doing in-kernel updates to only > necessary kdump kernel kexec segments which describe CPU and Memory > resources of the running kernel to the kdump kernel. > > The kernel changes related to in-kernel updates to the kdump kernel > kexec segments are kept under the CRASH_HOTPLUG config option. > > Later in the series, a powerpc crash hotplug handler is introduced to > update the kdump kernel kexec segments on CPU/Memory hotplug events. > This arch-specific handler is triggered from a generic crash handler > that registers with the CPU/Memory add/remove notifiers. > > The CRASH_HOTPLUG config option is enabled by default. > > Signed-off-by: Sourabh Jain > Reviewed-by: Laurent Dufour I can't remember having sent a review-by on that patch earlier. Anyway, I can't find any issue with that one, so replace with: Reviewed-by: Laurent Dufour > --- > arch/powerpc/Kconfig | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index a6c4407d3ec83..ac0dc0ffe89b4 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -681,6 +681,18 @@ config CRASH_DUMP > The same kernel binary can be used as production kernel and dump > capture kernel. > > +config CRASH_HOTPLUG > + bool "In-kernel update to kdump kernel on system configuration changes" > + default y > + depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG) > + help > + Quick and efficient mechanism to update the kdump kernel in the > + event of CPU/Memory hot plug/unplug or online/offline events. This > + approach does the in-kernel update to only necessary kexec segment > + instead of unload-reload entire kdump kernel from userspace. > + > + If unsure, say Y. > + > config FA_DUMP > bool "Firmware-assisted dump" > depends on PPC64 && (PPC_RTAS || PPC_POWERNV) _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec