Why does the GRUB_CMDLINE_LINUX parameter in the /etc/default/grub file not override the kernel command line parameters in all BLS snippets after I execute the grub2-mkconfig command?

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Linux operating system issue

Why does the GRUB_CMDLINE_LINUX parameter in the /etc/default/grub file not override the kernel command line parameters in all BLS snippets after I execute the grub2-mkconfig command?

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Why does the GRUB_CMDLINE_LINUX parameter in the /etc/default/grub file not override the kernel command line parameters in all BLS snippets after I execute the grub2-mkconfig command?

Causes

This may occur because the value of the GRUB_ENABLE_BLSCFG parameter in the /etc/default/grub file of the CentOS operating system has been modified from the default value to true, which changes the default behavior of grub2-mkconfig.

warning

This change is due to an update in the configuration method of the crashkernel parameter by kexec-tools. Overriding the kernel command line in Boot Loader Specification (BLS) snippets will result in the loss of the crashkernel parameter and failure to start the kdump service. Learn more.

Solutions

You can add the --update-bls-cmdline option when you execute the grub2-mkconfig command. The system will update the kernel command line in the BLS snippets according to GRUB_CMDLINE_LINUX.

grub2-mkconfig -o </path/to/grub.cfg> --update-bls-cmdline

tip

Replace </path/to/grub.cfg> with the actual grub.cfg path.

You can also use the grubby command to modify the BLS code snippet for the specified kernel.

grubby --update-kernel </path/to/kernel> --args "<new args>"

Description

Replace </path/to/kernel> with the actual path to the kernel file. Replace <new args> with the actual kernel parameters.

If you want to modify kernel parameters in the CentOS Stream 9 operating system, we recommend that you use this method.

Last updated: 2026.04.13 16:50:03

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