Red Hat Summit15.9. Enabling and disabling the kdump service
You can configure to enable or disable the kdump functionality on a specific kernel or on all installed kernels. You must routinely test the kdump functionality and validate its operates correctly.
Prerequisites
- You have root permissions on the system.
-
You have completed
kdumprequirements for configurations and targets. See Supported kdump configurations and targets. -
All configurations for installing
kdumpare set up as required.
Procedure
Enable the
kdumpservice formulti-user.target:# systemctl enable kdump.serviceStart the service in the current session:
# systemctl start kdump.serviceStop the
kdumpservice:# systemctl stop kdump.serviceDisable the
kdumpservice:# systemctl disable kdump.service
It is advisable to set kptr_restrict=1 as default. When kptr_restrict is set to (1) as default, the kdumpctl service loads the crash kernel regardless of Kernel Address Space Layout (KASLR) is enabled.
If kptr_restrict is not set to 1 and KASLR is enabled, the contents of /proc/kore file are generated as all zeros. The kdumpctl service fails to access the /proc/kcore file and load the crash kernel. The kexec-kdump-howto.txt file displays a warning message to set kptr_restrict=1. Verify for the following in the sysctl.conf file to ensure that kdumpctl service loads the crash kernel:
-
Kernel
kptr_restrict=1in thesysctl.conffile.
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