From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sourabh Jain Date: Tue, 26 Apr 2022 09:40:29 +0530 Subject: [RFC v4 PATCH 2/5] powerpc/crash hp: introduce a new config option CRASH_HOTPLUG In-Reply-To: <35ccca7c-07c2-1fc4-70da-2cc581ba818a@oracle.com> References: <20220411084357.157308-1-sourabhjain@linux.ibm.com> <20220411084357.157308-3-sourabhjain@linux.ibm.com> <874k2mfz5t.fsf@mpe.ellerman.id.au> <35ccca7c-07c2-1fc4-70da-2cc581ba818a@oracle.com> Message-ID: <9bf9eccf-d689-463d-0af2-5b3c65da4aef@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 20:59, Eric DeVolder wrote: > > > On 4/21/22 06:34, 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. > > Sourabh, > > Borislav Petkov also requested I remove the config option, which will > be the > case in upcoming v8. > > Where I was using CONFIG_CRASH_HOTPLUG, I've replaced it with the > CONFIG_HOTPLUG_CPU || CONFIG_MEMORY_HOTPLUG. Yes good idea. Even Michael suggested there is no need for new CONFIG option. I will also remove CRASH_HOTPLUG config in the next version. Thanks, Sourabh Jain