From f022398ddbd09f3147cd3a16379b56996cb15c54 Mon Sep 17 00:00:00 2001 From: Kazuhito Hagio Date: Thu, 17 Jan 2019 15:31:25 -0500 Subject: [PATCH] earlykdump: Add a note of final_action option to avoid crash loop Since early kdump is generally used for capturing vmcore when boot-time panic occurs, if a system always reboots after capturing vmcore, it can go into a crash loop. To avoid this issue, this patch add a note of 'final_action' option to the early kdump document. Signed-off-by: Kazuhito Hagio Cc: Dave Young Cc: Lianbo Jiang Acked-by: Bhupesh Sharma Acked-by: Dave Young Signed-off-by: Kairui Song --- early-kdump-howto.txt | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/early-kdump-howto.txt b/early-kdump-howto.txt index fe4f13f..9af0ef1 100644 --- a/early-kdump-howto.txt +++ b/early-kdump-howto.txt @@ -1,6 +1,7 @@ Early Kdump HOWTO Introduction +------------ Kdump service starts too late, so early crashes will have no chance to get kdump kernel booting, this will cause crash information to be lost. It is @@ -12,7 +13,8 @@ which is disabled by default. For the normal kdump service, it can check whether the early kdump has loaded the crash kernel and initramfs. It has no conflict with the early kdump. -How to configure early kdump: +How to configure early kdump +---------------------------- We assume if you're reading this document, you should already have kexec-tools installed. @@ -21,6 +23,16 @@ You can rebuild the initramfs with earlykdump support with below steps: 1. start kdump service to make sure kdump initramfs is created. # systemctl start kdump + NOTE: If a crash occurs during boot process, early kdump captures a vmcore + and reboot the system by default, so the system might go into crash loop. + You can avoid such a crash loop by adding the following settings, which + power off the system after dump capturing, to kdump.conf in advance: + + final_action poweroff + failure_action poweroff + + For the failure_action, you can choose anything other than "reboot". + 2. rebuild system initramfs with earlykdump support. # dracut --add earlykdump @@ -50,5 +62,6 @@ kdump kernel Mar 09 10:02:47 localhost.localdomain dracut-cmdline[189]: early-kdump is disabled. Limitation +---------- At present, early kdump doesn't support fadump.