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Debugging kernel crashes using kdump
Memory must be reserved for the crash kernel during booting of the first kernel. `crashkernel=auto` is likely insufficient memory on Fedora CoreOS. It is recommended to start testing with 300M. Kernel arguments can be provided like this:
sudo rpm-ostree kargs --append='crashkernel=300M'
xref:kernel-args.adoc[More information] on how to modify kargs via `rpm-ostree`.
By default, the path in which the vmcore will be saved is `/var/crash`. It is also possible to write the dump over the network or to some other location on the local system by editing `/etc/kdump.conf`. For additional information, see https://www.mankier.com/5/kdump.conf[`kdump.conf(5)`] and the comments in `/etc/kdump.conf` and `/etc/sysconfig/kdump`.
Enable the kdump systemd service.
sudo systemctl enable kdump.service
Reboot your system.
sudo systemctl reboot
It is highly recommended to test the configuration after setting up the `kdump` service, with extra attention to the amount of memory reserved for the crash kernel. For information on how to test that kdump is properly armed and how to analyze the dump, refer to the https://fedoraproject.org/wiki/How_to_use_kdump_to_debug_kernel_crashes[kdump documentation for Fedora] and https://www.kernel.org/doc/html/latest/admin-guide/kdump/kdump.html[the Linux kernel documentation on kdump].