Configuring kexec / kdump

English Hardware
#1

First off my question: How does a custom KDUMP-COMMANDLINE need to look like?

Ok, so here is my problem:

  • I’ve configured kexec (kexec-bootloader
    ) and set the reboot-target to kexec (ln -s /usr/lib/systemd/system/kexec.target /etc/systemd/system/reboot.target)

And this works, it restarts the system without even going into the bootloader.

BUT, I get a kernel-panic:

[INDENT=2][/INDENT]
VFS: Cannot open root device “UUID=04ff7457-c4af-44d3-b874-8baf961c22a4” or unknown-block(0,0): error -6
Please append a correct “root=” boot option; here are the available partitions:
…

As I understand it, kexec, or more specific kdump uses the “kdump_commandline” from the “sysconfig/kdump” configuration file and if that’s empty (default), then it uses and modifies “/proc/cmdline” to set its boot parameters.

I can get that kdump-commandline via “kexec-bootloader -D”, right?get_grubonce_and_reset_magic(): No /boot/grub/default.
GRUB Default: -1
Type : image
Name : openSUSE Leap 42.1
Image : /boot/vmlinuz-4.1.27-27-default
Initrd :
VGA : 0x31a
Append : ${extra_cmdline} video=1280x1024 resume=/dev/disk/by-uuid/84df30c8-2eab-4aa6-8b7b-6d6c94b07aeb showopts elevator=deadline
Root : UUID=04ff7457-c4af-44d3-b874-8baf961c22a4
Kexec call: kexec -l ‘/boot/vmlinuz-4.1.27-27-default’ --append='root=UUID=04ff7457-c4af-44d3-b874-8baf961c22a4 ${extra_cmdline} video=1280x1024 resume=/dev/disk/by-uuid/84df30c8-2eab-4aa6-8b7b-6d6c94b07aeb showopts elevator=deadline ’

So if I wanted/needed to change the root-parameter, I would need to add this line to “/etc/sysconfig/kdump”

kdump_commandline=“kexec -l ‘/boot/vmlinuz-4.1.27-27-default’ --append=‘root=/dev/sda2 ${extra_cmdline} video=1280x1024 resume=/dev/sda1 showopts elevator=deadline’”

But “man kdump” says the following:

If you manually create a command line, make sure to include:

  • · the root parameter,*
  • · any console parameters (for serial console),*
  • · irqpoll,*
  • · reset_devices,*
  • · elevator=deadline to save the memory footprint.*
    The last three parameters are special for kdump and should always be included, if you don’t have a good reason to exclude them.

So I somehow need to add “irqpoll, reset_devices” to the command.

Now, I couldn’t find anywhere, how this variable should be configured, or if this even works for kexec…

I’m stumped right now… I just cannot get kexec to reboot with “root=/dev/sda2”

#2

KDUMP_COMMANDLINE (all caps) in /etc/sysconfig/kdump should not contain the kexec command, only the command line parameters, like this:

KDUMP_COMMANDLINE="1 irqpoll maxcpus=1 reset_devices root=/dev/sda2 noresume vga=normal elevator=deadline i915.modeset=0 console=ttyS0,9600n8 console=ttyUSB0,9600n8 console=ttyUSB1,9600n8 console=tty0"

It is better to use KDUMP_COMMANDLINE_APPEND if possible, instead, e.g.,

KDUMP_COMMANDLINE_APPEND="root=/dev/sda2"

That will allow kdump to use its own options and interfere less in the process.

#3

True; forgot this when writing this post^^

Well, I just pretty much fooled around with whatever I could find on kexec/kdump, because of this stupid panic on reboot… And unfortunately your suggestion didn’t help in this regard :frowning:
Do you have any idea what could cause this error?

VFS: Cannot open root device "UUID=04ff7457-c4af-44d3-b874-8baf961c22a4" or unknown-block(0,0)