How to pass kernel command line parameters from Dracut

[Archie1]

In my related post about Dracut, it was mentioned that the key kernel_cmdline cannot be used by dracut in EOS. This is because while building the EOS initramfs the command used is
/usr/bin/dracut --force --hostonly --no-hostonly-cmdline /boot/initramfs-linux-lts.img

Here the main option is –no-hostonly-cmdline. According to dracut documentation this option implies that

Do not store kernel command line arguments needed in the initramfs. Ensures that dracut modules are not allowed to generate and store host-specific initrd arguments in the etc/cmdline.d directory inside the generated initrd.

This implies that if I wanted to pass the following parameters rd.luks=0 rd.lvm=0 rd.md=0 rd.dm=0 I cannot do it using a configuration file inside the directory /etc/dracut.conf.d/. So the question is then how do I pass these options to dracut?

I am trying to pass this information so as to speed up the boot time. As per the documentation of dracut, link given above,

Speeding up the Boot Process

If you want to speed up the boot process, you can specify as much information for dracut on the kernel command as possible. For example, you can tell dracut, that you root partition is not on a LVM volume or not on a raid partition, or that it lives inside a specific crypto LUKS encrypted volume. By default, dracut searches everywhere. A typical dracut kernel command line for a plain primary or logical partition would contain:

rd.luks=0 rd.lvm=0 rd.md=0 rd.dm=0

This turns off every automatic assembly of LVM, MD raids, DM raids and crypto LUKS.

I also had a look at the forum post from about 1-2 years ago where this was discussed, but it seems that there have been some changes done which now prevent the key kernel_cmdline from being used.

I would not want to change the existing hooks of EOS present in the directory /usr/lib/dracut/dracut.conf.d/.

All help and clarifications on this would be appreciated.

[mbod]

@Archie1

This implies that if I wanted to pass the following parameters rd.luks=0 rd.lvm=0 rd.md=0 rd.dm=0 I cannot do it using a configuration file inside the directory /etc/dracut.conf.d/. So the question is then how do I pass these options to dracut?

dracut uses the kernel commandline from here: /etc/kernel/cmdline
Just put your options in that file and do a reinstall-kernels But dont be disappointed. The boot speedup is insignificant.

[Archie1]

@mbod

@Archie1

This implies that if I wanted to pass the following parameters rd.luks=0 rd.lvm=0 rd.md=0 rd.dm=0 I cannot do it using a configuration file inside the directory /etc/dracut.conf.d/. So the question is then how do I pass these options to dracut?

dracut uses the kernel commandline from here: /etc/kernel/cmdline
Just put your options in that file and do a reinstall-kernels But dont be disappointed. The boot speedup is insignificant.

Thanks @mbod. The file /etc/kernel/cmdline does not exist on my system. Please see the output given below for more details.

$ ls -al /etc/kernel/cmdline
ls: cannot access '/etc/kernel/cmdline': No such file or directory
$ 
$ ls -alpF /etc/kernel/
total 20
drwxr-xr-x  3 root root  4096 Feb  8  2025 ./
drwxr-xr-x 99 root root 12288 Sep  9 11:52 ../
drwxr-xr-x  2 root root  4096 Jan 13  2025 install.d/
$

I am using GRUB2 for my boot loader and not systemd-boot.

[mbod]

@Archie1

I am using GRUB2 for my boot loader and not systemd-boot.

In that case you should add kernel parameters to /etc/default/grub

Add kernel parameter to dracut

I try to add iomem=relaxed as kernel parameters. I tried adding it to /etc/dracut.conf.d/cmdline.conf as kernel_cmdline=“iomem=relaxed” and than tried every combination of: dracut -force dracut --regenerate-all --force reinstall-kernel but the parameter will not work. Manually adding it at boot time works… What am i missing?

[Archie1]

Will Kernel understand the parameters, rd.luks=0 rd.lvm=0 rd.md=0 rd.dm=0 passed on from GRUB configuration? I was under the impression that these were for the initramfs only.

[mbod]

No, it is kernel commandline parameters.

This is what you just posted here:

@Archie1

A typical dracut kernel command line for a plain primary or logical partition would contain:

rd.luks=0 rd.lvm=0 rd.md=0 rd.dm=0