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Tue, 26 Apr 2022 03:47:49 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 99F9E11C04A; Tue, 26 Apr 2022 03:47:49 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A583411C04C; Tue, 26 Apr 2022 03:47:47 +0000 (GMT) Received: from [9.43.122.72] (unknown [9.43.122.72]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 26 Apr 2022 03:47:47 +0000 (GMT) Message-ID: <3cbf4010-cbbc-e357-21a0-f50f829097b4@linux.ibm.com> Date: Tue, 26 Apr 2022 09:17:46 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [RFC v4 PATCH 2/5] powerpc/crash hp: introduce a new config option CRASH_HOTPLUG Content-Language: en-US To: Michael Ellerman , linuxppc-dev@ozlabs.org References: <20220411084357.157308-1-sourabhjain@linux.ibm.com> <20220411084357.157308-3-sourabhjain@linux.ibm.com> <874k2mfz5t.fsf@mpe.ellerman.id.au> From: Sourabh Jain In-Reply-To: <874k2mfz5t.fsf@mpe.ellerman.id.au> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: bovgfUgSzOxU88fBgSciTxOETVTezNET X-Proofpoint-GUID: 9KgeVuKikEnWq1gE99ZMzRzlpKKxe8GN X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-04-26_01,2022-04-25_03,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 suspectscore=0 phishscore=0 spamscore=0 impostorscore=0 malwarescore=0 clxscore=1015 adultscore=0 lowpriorityscore=0 mlxlogscore=999 bulkscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2204260021 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, eric.devolder@oracle.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 21/04/22 17:04, Michael Ellerman wrote: > Sourabh Jain writes: >> The option CRASH_HOTPLUG enables, in kernel update to kexec segments on >> hotplug events. >> >> All the updates needed on the capture kernel load path in the kernel for >> both kexec_load and kexec_file_load system will be kept under this config. >> >> Signed-off-by: Sourabh Jain >> Reviewed-by: Eric DeVolder >> --- >> arch/powerpc/Kconfig | 11 +++++++++++ >> 1 file changed, 11 insertions(+) >> >> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig >> index b779603978e1..777db33f75b5 100644 >> --- a/arch/powerpc/Kconfig >> +++ b/arch/powerpc/Kconfig >> @@ -623,6 +623,17 @@ config FA_DUMP >> If unsure, say "y". Only special kernels like petitboot may >> need to say "N" here. >> >> +config CRASH_HOTPLUG >> + bool "kernel updates of crash kexec segments" >> + depends on CRASH_DUMP && (HOTPLUG_CPU) && KEXEC_FILE >> + help >> + An efficient way to keep the capture kernel up-to-date with CPU >> + hotplug events. On CPU hotplug event the kexec segments of capture >> + kernel becomes stale and need to be updated with latest CPU data. >> + In this method the kernel performs minimal update to only relevant >> + kexec segments on CPU hotplug event, instead of triggering full >> + capture kernel reload from userspace using udev rule. > Why would a user ever want to turn this off? > > Seems to me we should just make it always behave this way, and not have > a CONFIG option at all. Yes, we don't need a new CONFIG option. Thanks for the suggestion. Thanks, Sourabh Jain From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sourabh Jain Date: Tue, 26 Apr 2022 09:17:46 +0530 Subject: [RFC v4 PATCH 2/5] powerpc/crash hp: introduce a new config option CRASH_HOTPLUG In-Reply-To: <874k2mfz5t.fsf@mpe.ellerman.id.au> References: <20220411084357.157308-1-sourabhjain@linux.ibm.com> <20220411084357.157308-3-sourabhjain@linux.ibm.com> <874k2mfz5t.fsf@mpe.ellerman.id.au> Message-ID: <3cbf4010-cbbc-e357-21a0-f50f829097b4@linux.ibm.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kexec@lists.infradead.org On 21/04/22 17:04, Michael Ellerman wrote: > Sourabh Jain writes: >> The option CRASH_HOTPLUG enables, in kernel update to kexec segments on >> hotplug events. >> >> All the updates needed on the capture kernel load path in the kernel for >> both kexec_load and kexec_file_load system will be kept under this config. >> >> Signed-off-by: Sourabh Jain >> Reviewed-by: Eric DeVolder >> --- >> arch/powerpc/Kconfig | 11 +++++++++++ >> 1 file changed, 11 insertions(+) >> >> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig >> index b779603978e1..777db33f75b5 100644 >> --- a/arch/powerpc/Kconfig >> +++ b/arch/powerpc/Kconfig >> @@ -623,6 +623,17 @@ config FA_DUMP >> If unsure, say "y". Only special kernels like petitboot may >> need to say "N" here. >> >> +config CRASH_HOTPLUG >> + bool "kernel updates of crash kexec segments" >> + depends on CRASH_DUMP && (HOTPLUG_CPU) && KEXEC_FILE >> + help >> + An efficient way to keep the capture kernel up-to-date with CPU >> + hotplug events. On CPU hotplug event the kexec segments of capture >> + kernel becomes stale and need to be updated with latest CPU data. >> + In this method the kernel performs minimal update to only relevant >> + kexec segments on CPU hotplug event, instead of triggering full >> + capture kernel reload from userspace using udev rule. > Why would a user ever want to turn this off? > > Seems to me we should just make it always behave this way, and not have > a CONFIG option at all. Yes, we don't need a new CONFIG option. Thanks for the suggestion. Thanks, Sourabh Jain