Arch Linux

Felixoid

Member

Registered: 2012-05-23

Posts: 30

The `kexec -p` doesn't work

Hello dear colleagues.

I've set up the kdump according to the wiki page, and tested it as both

kexec /boot/vmlinuz-linux .....

and

kexec -l /boot/vmlinuz-linux ... && kexec -e

, and it works.

But when I catch a kernel panic, the host just hangs, and nothing moves. And when I test is as the following script, it hangs forever as well:

> sudo cat /root/crash.sh
sync
echo 1 > /proc/sys/kernel/sysrq
echo c > /proc/sysrq-trigger
> sudo bash -x /root/crash.sh
+ sync

here's my systemd service file for the kdump and kernel parameters:

> cat /etc/systemd/system/kdump.service
[Unit]
Description=Load the kdump kernel
After=local-fs.target

[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/usr/bin/kexec -p /boot/vmlinuz-linux --initrd=/boot/initramfs-linux.img --append="cryptdevice=UUID=82302b8c-9628-4fab-b728-b414ed6fe596:cLVM root=/dev/cLVM/root amd_pstate=active irqpoll nr_cpus=1 reset_devices systemd.mask=kdump.service"
ExecStop=/usr/bin/kexec -p -u

[Install]
WantedBy=multi-user.target

> cat /etc/kernel/cmdline
cryptdevice=UUID=82302b8c-9628-4fab-b728-b414ed6fe596:cLVM root=/dev/cLVM/root amd_pstate=active systemd.journald.forward_to_console=1 console=tty1 pause_on_oops=15 crashkernel=7500M

I know that `crashkernel=7500M` is a bit too much, but set it just out of curiosity if it would help at all.

Additional info:
I use the standard `core/linux` package, and here's my mkinitcpio and sbctl config:

> grep -v '^#' /etc/mkinitcpio.conf
MODULES=(radeon)

BINARIES=()

FILES=()

HOOKS=(base udev autodetect microcode keyboard keymap modconf kms block encrypt lvm2 filesystems fsck)

# I use sbctl to build UEFI bundle
> cat /var/lib/sbctl/bundles.json
{
    "/boot/EFI/Linux/arch-linux.efi": {
        "output": "/boot/EFI/Linux/arch-linux.efi",
        "intel_microcode": "",
        "amd_microcode": "/boot/amd-ucode.img",
        "kernel_image": "/boot/vmlinuz-linux",
        "initramfs": "/boot/initramfs-linux.img",
        "cmdline": "/etc/kernel/cmdline",
        "splash": "/usr/share/systemd/bootctl/splash-arch.bmp",
        "os_release": "/usr/lib/os-release",
        "efi_stub": "/usr/lib/systemd/boot/efi/linuxx64.efi.stub",
        "esp": "/boot"
    }
}

Last edited by Felixoid (2025-01-16 21:01:42)

Felixoid

Member

Registered: 2012-05-23

Posts: 30

Re: The `kexec -p` doesn't work

And even more. Without `kexec -p` being executed, if I just run the `sudo bash -x /root/crash.sh`, my screen just hangs, and I can't see the kernel messages.

Despite if I run it in plasma 6 graphic session (launched from sddm), or from tty3.

Felixoid

Member

Registered: 2012-05-23

Posts: 30

Re: The `kexec -p` doesn't work

after I added `amdgpu.dcdebugmask=0x10` to the /etc/kernel/cmdline, the laptop didn't hang, but rebooted instantly. Probably, it was a very bad idea