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earlykdump: Add a note of final_action option to avoid crash loop

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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 <k-hagio@ab.jp.nec.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Lianbo Jiang <lijiang@redhat.com>
Acked-by: Bhupesh Sharma <bhsharma@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Kairui Song <kasong@redhat.com>
This commit is contained in:
Kazuhito Hagio 2019-01-17 15:31:25 -05:00 committed by Kairui Song
parent 242da37c58
commit f022398ddb
1 changed files with 14 additions and 1 deletions
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15
early-kdump-howto.txt
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@ -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.