Add kernel commandline args with dracut ... not showing up in /proc/cmdline

[pickle.dogcart]

I am trying to install the system76-driver package. At the end of install, this info/note is emitted:

   The System76 Driver package provides the following system services:  
  
       system76.service             System76 airplane-mode hotkey and LED support  
  
   (!) To use system76.service, you must add "ec_sys.write_support=1" to your kernel command line  

Since this is a new install using dracut, I figured that it would be as simple as:

[root@my-host dracut.conf.d]# cat /etc/dracut.conf.d/system76-kernel.conf 
# Needed for system76.service
# See: https://support.system76.com/articles/system76-software/
kernel_cmdline+=" ec_sys.write_support=1 "

[root@my-host dracut.conf.d]# dracut-rebuild

And then a reboot.

But after a reboot, I don’t see the command line in /proc/cmdline. I got curious and started looking into how dracut-rebuild worked:

[root@my-host dracut.conf.d]# cat $(which dracut-rebuild)
#!/usr/bin/env bash
#
# Rebuild all the initrds using dracut

# This finds the best token for systemd-boot
find_token() {
    if [[ -s /etc/kernel/entry-token ]] ; then
        cat /etc/kernel/entry-token
    elif [[ -s /etc/machine-id ]] ; then
        cat /etc/machine-id
    elif [[ $(grep "^IMAGE_ID=" /etc/os-release) ]] ; then
        grep "^IMAGE_ID=" /etc/os-release | awk -F"=" '{print $2}'
    elif [[ $(grep "^ID=" /etc/os-release) ]] ; then
        grep "^ID=" /etc/os-release | awk -F"=" '{print $2}'
    fi
}

[[ -f /etc/kernel-install-for-dracut.conf ]] && source /etc/kernel-install-for-dracut.conf
ESP=$(bootctl --print-esp-path)
TOKEN=$(find_token)
while read -r pkgbase; do
    kernelversion=$(basename "${pkgbase%/pkgbase}")
    kernelname=$(cat "${pkgbase}")
    INITRD_PATH="${ESP}/${TOKEN}/${kernelversion}"
    if [[ ! -d "$INITRD_PATH" ]] ; then
        echo 'Failed to build initrds, use "sudo reinstall-kernels" instead' 1>&2
        exit 1
    fi
    echo "Running dracut for ${kernelname}-${kernelversion}"
    [[ ${DRACUT_QUIET} == "true" ]] && DRACUT_EXTRA_PARAMS=" --quiet"
    dracut --force --hostonly --no-hostonly-cmdline${DRACUT_EXTRA_PARAMS} "${INITRD_PATH}/initrd" "${kernelversion}"
    [[ ${NO_DRACUT_FALLBACK} != "true" ]] && dracut --force --no-hostonly${DRACUT_EXTRA_PARAMS} "${INITRD_PATH}/initrd-fallback" "${kernelversion}"
done < <(find /usr/lib/modules -maxdepth 2 -type f -name pkgbase)

The docs offer seemingly conflicting details about the --hostonly and ``-no-hostonly-cmdline` options.

My question:

1. What do i need to do to add kernel commandline args?

[dalto]

@pickle.dogcart

What do i need to do to add kernel commandline args?

Edit /etc/kernel/cmdline and then run sudo reinstall-kernels

[ivanhoe]

Not that I have anything to tell - but…

There’s probably a difference between

@pickle.dogcart

"ec_sys.write_support=1"

And

@pickle.dogcart

kernel_cmdline+=" ec_sys.write_support=1 "

Maybe the syntax is correct, I can’t tell, but it caught my eye…

[pickle.dogcart]

@dalto

Edit /etc/kernel/cmdline and then run sudo reinstall-kernels

That did the trick! Just curious, WHY is the change done here and not via the dracut conf files?

[dalto]

@pickle.dogcart

WHY is the change done here and not via the dracut conf files?

Because we manage our kernel command lines via our bootloaders. As for why, I don’t think it was a conscious choice. It was the way it worked when we were using mkinitcpio and we continued to do it once we switched to dracut.

That being said, I am not sure there is a significant difference either way.