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  1. Bug #1918085
  2. Comment #7

Comment 7 for bug 1918085

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Dmitry-a-durnev (dmitry-a-durnev) wrote (last edit ):

I see the same message in 22.04.3:

[ 0.049372] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-5.15.0-91-generic root=UUID=... ro quiet splash crashkernel=512M-:192M vt.handoff=7
[ 0.049461] Unknown kernel command line parameters "splash BOOT_IMAGE=/boot/vmlinuz-5.15.0-91-generic", will be passed to user space.

But, for me (16 GB RAM) changing to crashkernel=192M-:512M not fixes anything. It just increases kexec_crash_size to 512 MB which is too much and not makes crash dump appear(for me it is still missing). The message about "unknown ...parameters" is not relevant itself, could be ignored?

"crashkernel=512M-:192M" is correct by itself (is NOT a syntax or any error) and means: for RAM size more than 512M reserve 192M for crashkernel,

see dmesg (example for the case of :192M-:512M):

Reserving 512MB of memory at 2096MB for crashkernel (System RAM: 16323MB)

Syntax is correct: "512M-:192M" is <range>:<size>, where range=start-[end]:

  'start' is inclusive and 'end' is exclusive

512M is 'start', [end] is optional and not specified

192M is size. Read the docs:

https://ubuntu.com/server/docs/kernel-crash-dump