Re: [PATCH] kexec: dump kmessage before machine_kexec

From: Petr Mladek
Date: Mon Jun 08 2020 - 04:06:34 EST


On Fri 2020-06-05 15:46:42, Pavel Tatashin wrote:
> kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before
> machine_restart(), machine_halt(), machine_power_off(), the only one that
> is missing is machine_kexec().
>
> The dmesg output that it contains can be used to study the shutdown
> performance of both kernel and systemd during kexec reboot.
>
> Here is example of dmesg data collected after kexec:
>
> root@dplat-cp22:~# cat /sys/fs/pstore/dmesg-ramoops-0 | tail
> ...
> <6>[ 70.914592] psci: CPU3 killed (polled 0 ms)
> <5>[ 70.915705] CPU4: shutdown
> <6>[ 70.916643] psci: CPU4 killed (polled 4 ms)
> <5>[ 70.917715] CPU5: shutdown
> <6>[ 70.918725] psci: CPU5 killed (polled 0 ms)
> <5>[ 70.919704] CPU6: shutdown
> <6>[ 70.920726] psci: CPU6 killed (polled 4 ms)
> <5>[ 70.921642] CPU7: shutdown
> <6>[ 70.922650] psci: CPU7 killed (polled 0 ms)
>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>

Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>

Best Regards,
Petr