Arch Linux

aleksF

Member

Registered: 2019-03-09

Posts: 19

Kdump set up correctly, but the dump capture kernel won't load.

Hi everyone,

I have a Kdump-headache!

I'm trying to troubleshoot some random kp's (blinking caps lock) on my DELL XPS 13 2 in 1 9310.

CPU: 11th Gen Intel® Core™ i7-1165G7 @ 2.80GHz × 8
Graphics: Mesa Intel® Xe Graphics (TGL GT2)
Current Kernel: Arch stock kernel 5.10.56-1-lts

I followed the arch wiki page about kdump.

1 - I checked that the stock Arch kernel has the right 3 config options required in the wiki with zcat /proc/config.gz

2 - I am running the LTS arch kernel (5.10), and using the stock Arch kernel as kdump kernel (5.13.12), hence my kdump.service looks like this:

[Unit]
Description=Load dump capture kernel
After=local-fs.target

[Service]
ExecStart=/usr/bin/kexec -p /boot/vmlinuz-linux --initrd=/boot/initramfs-linux-fallback.img --append="root=UUID=dada41bb-dfc1-4002-9edd-7f2af05fae87 systemd.unit=kdump-save.service irqpoll nr_cpus=1 reset_devices"
Type=oneshot

[Install]
WantedBy=multi-user.target

This has been enabled with systemctl.

3 - I checked this, and made sure the UUID of root is the same.

$ cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-linux-lts root=UUID=dada41bb-dfc1-4002-9edd-7f2af05fae87 rw crashkernel=512M i915.enable_psr=0

4 - And this

$ cat /sys/kernel/kexec_crash_loaded 
1

All looks good!
Yet if I cause a crash with:

echo c > /proc/sysrq-trigger

Nothing comes up. I have also set up kdump-save.service as per wiki, yet nothing happens. Computer stays frozen. Obviously, nothing appears after reboot in /var/crash or /proc/vmcore

What am I missing?

Also, if this topic is not approriate for Newbie corner, let me know and I will repost to a different section. I am a newbie with arch.

Last edited by aleksF (2021-08-19 18:50:53)

Gero

Member

Registered: 2016-06-26

Posts: 3

Re: Kdump set up correctly, but the dump capture kernel won't load.

Hi @aleksF,

You ever made any progress on this by chance?
As far as I can tell I've followed the exact same steps, all gathered from the Arch Wiki on kdump, with the same result: computer stays frozen after "echo c > /proc/sysrq-trigger", without ever booting the new kernel.

One additional thing I tested, using kexec -l with the exact same arguments, and then booting with kexec -e DOES work..

Ie:

kexec -l /boot/vmlinuz-linux --initrd=/boot/initramfs-linux-fallback.img --append="root=UUID=<my-uuid> single irqpoll nr_cpus=1 reset_devices"
kexec -e

does correctly boot me into single-user from current kernel.

Last edited by Gero (2022-01-01 21:53:36)