From b2075dbb15d7ae952aeb01331198f4dc45a7e46a Mon Sep 17 00:00:00 2001 From: Pavel Tatashin Date: Thu, 6 May 2021 18:04:41 -0700 Subject: [PATCH] kexec: dump kmessage before machine_kexec kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before machine_restart(), machine_halt(), and 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 ... [ 70.914592] psci: CPU3 killed (polled 0 ms) [ 70.915705] CPU4: shutdown [ 70.916643] psci: CPU4 killed (polled 4 ms) [ 70.917715] CPU5: shutdown [ 70.918725] psci: CPU5 killed (polled 0 ms) [ 70.919704] CPU6: shutdown [ 70.920726] psci: CPU6 killed (polled 4 ms) [ 70.921642] CPU7: shutdown [ 70.922650] psci: CPU7 killed (polled 0 ms) Link: https://lkml.kernel.org/r/20210319192326.146000-2-pasha.tatashin@soleen.com Signed-off-by: Pavel Tatashin Reviewed-by: Kees Cook Reviewed-by: Petr Mladek Reviewed-by: Bhupesh Sharma Acked-by: Baoquan He Reviewed-by: Tyler Hicks Cc: James Morris Cc: Sasha Levin Cc: Eric W. Biederman Cc: Anton Vorontsov Cc: Colin Cross Cc: Tony Luck Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/kexec_core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index f04d04d1b855..f099baee3578 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -37,6 +37,7 @@ #include #include #include +#include #include #include @@ -1179,6 +1180,7 @@ int kernel_kexec(void) machine_shutdown(); } + kmsg_dump(KMSG_DUMP_SHUTDOWN); machine_kexec(kexec_image); #ifdef CONFIG_KEXEC_JUMP -- 2.34.1