From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric DeVolder Date: Thu, 21 Apr 2022 10:29:44 -0500 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: <35ccca7c-07c2-1fc4-70da-2cc581ba818a@oracle.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kexec@lists.infradead.org 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. Eric > > cheers >