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Tue, 14 Mar 2023 05:17:58 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B47B22004D; Tue, 14 Mar 2023 05:17:58 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 19BF820063; Tue, 14 Mar 2023 05:17:57 +0000 (GMT) Received: from [9.43.46.246] (unknown [9.43.46.246]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 14 Mar 2023 05:17:56 +0000 (GMT) Message-ID: <9fdde88b-13e7-bf3e-d417-5479a60acb6a@linux.ibm.com> Date: Tue, 14 Mar 2023 10:47:56 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v9 2/6] powerpc/crash: introduce a new config option CRASH_HOTPLUG Content-Language: en-US To: Eric DeVolder , linuxppc-dev@ozlabs.org, mpe@ellerman.id.au References: <20230312181154.278900-1-sourabhjain@linux.ibm.com> <20230312181154.278900-3-sourabhjain@linux.ibm.com> <0269c298-d53c-7ad7-c718-3dbc1e225d0d@oracle.com> From: Sourabh Jain In-Reply-To: <0269c298-d53c-7ad7-c718-3dbc1e225d0d@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: DIr4LSZphKBCPpVXY24IvfRd6lF0k8US X-Proofpoint-ORIG-GUID: OE5sumqNusd_JMJYzIhOSB3zVxFcF7m8 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=2023-03-13_13,2023-03-13_03,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 mlxscore=0 clxscore=1015 malwarescore=0 suspectscore=0 impostorscore=0 adultscore=0 mlxlogscore=999 spamscore=0 bulkscore=0 lowpriorityscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2303140044 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: ldufour@linux.ibm.com, kexec@lists.infradead.org, hbathini@linux.ibm.com, bhe@redhat.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 13/03/23 21:16, Eric DeVolder wrote: > > > On 3/12/23 13:11, Sourabh Jain wrote: >> Due to CPU/Memory hotplug events the system resources changes. A similar >> change should reflect in the loaded kdump kernel image that describes >> the state of the CPU and memory of the running kernel. >> >> If the kdump kernel image is not updated after the CPU or Memory hotplug >> events and it tries to collect the dump with the stale system resource >> data this might lead to dump collection failure or an inaccurate dump >> collection. >> >> The current method to keep the kdump kernel up to date is by triggering >> reload (i.e unload and load) the entire kdump kernel image whenever a >> CPU or Memory hotplug event is observed by udev in the userspace. >> Reloading the complete kdump kernel image is an expensive task. It can >> be easily avoided by doing the in-kernel updates to specific kdump >> kernel image components which are responsible for describing CPU and >> Memory resources of the running kernel to the kdump kernel. >> >> The kernel changes related to in-kernel update to the kdump kernel image >> on CPU/Memory hotplug events are kept under the CRASH_HOTPLUG config >> option. >> >> Later in the series, a powerpc crash hotplug handler is introduced to >> update the kdump kernel image on CPU/Memory hotplug events. This arch >> specific handler is trigger from a generic crash handler that registers >> with the CPU and memory notifiers. >> >> The CRASH_HOTPLUG config option is enabled by default. >> >> Signed-off-by: Sourabh Jain >> --- >>   arch/powerpc/Kconfig | 12 ++++++++++++ >>   1 file changed, 12 insertions(+) >> >> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig >> index a6c4407d3ec83..2f45b3f5175cb 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 "Update crash capture system on CPU/Memory hotplug event" > Fwiw, online/offline changes also flow through this infrastructure... > eric Yes I will update the CONFIG summary and commit message to convey the same. Thanks for the review. Thanks, Sourabh Jain