[RFC v3 PATCH 2/5] powerpc/crash hp: introduce a new config option CRASH_HOTPLUG

[Eric DeVolder]

On 3/21/22 03:04, Sourabh Jain wrote:
> 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 <sourabhjain at linux.ibm.com>

Reviewed-by: Eric DeVolder <eric.devolder at oracle.com>

> ---
>   arch/powerpc/Kconfig | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index b779603978e1..b816339ef8c7 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 hotplug event (CPU/memory) the kexec segments
> +	  of capture kernel becomes stale and need to be updated with latest
> +	  CPU and memory regions. In this method the kernel performs minimal
> +	  update to only relevant kexec segments on CPU hotplug event, instead
> +	  of triggering full capture reload from userspace using udev rule.
> +
>   config PRESERVE_FA_DUMP
>   	bool "Preserve Firmware-assisted dump"
>   	depends on PPC64 && PPC_POWERNV && !FA_DUMP
>