how to use CONFIG_KEXEC_JUMP options?

[Gioh Kim]

Hello,

"echo c > /proc/sysrq-trigger" generates the kernel dump but it reboots the
system.
I'd like to generate kernel dump without system reboot.

I found the CONFIG_KEXEC_JUMP option that described as "it is possible to
jump to the kdump kernel and generate kernel dump, and come back to the
operating kernel".
So I enabled CONFIG_KEXEC_JUMP option but I cannot figure out how to come
back to the operating kernel.

For example, I did following sequences after reading kexec manual page.

1. kexec --load=/boot/vmlinuz --initrd=/boot/initrd --reuse-cmdline
2. kexec -e
3. now kdump kernel is running
4. kexec --load-jump-back-helper --entry=<ADDRESS>
5. kexec -e

I can jump to kdump kernel with step 1 and step 2.
kexec manual says I need an entry address.
I don't know what address I should use.

Does anybody know how to use CONFIG_KEXEC_JUMP options and kexec to jump
between kdump kernel and operating kernel?


-- 

Best regards,
Gioh Kim
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