Fwd: [gentoo-dev] New News Item: 2026-xx-yy-dracut-hostonly-cmdline

On Sat, 2 May 2026 at 13:59, Nowa Ammerlaan <[email protected]> wrote:
> Title: Dracut changed default for hostonly_cmdline setting
> Author: Nowa Ammerlaan <[email protected]>
> Posted: 2026-xx-yy
> Revision: 1
> News-Item-Format: 2.0
> Display-If-Installed: >=sys-kernel/dracut-111
>
> Dracut is an initramfs generation tool. It may be invoked via the
> installkernel mechanism or manually after building custom kernels.
>
> What changed?
> ====================
>
> In version 111 of sys-kernel/dracut the default for the
> hostonly_cmdline setting changed from enabled to disabled. When
> enabled, this setting causes Dracut to attempt to detect which
> parameters are required on the kernel command line to boot the system.
> Examples are the root= parameter or parameters controlling partition
> decryption. These parameters are then included in the generated
> initramfs and appended to the kernel command line during boot.
>
> Why has this setting been changed
> ====================
>
> When enabled, Dracut's hostonly_cmdline setting may use the kernel
> command line of the running kernel (/proc/cmdline) to construct the
> kernel command line that will be embedded in the initramfs. This can
> cause problems when Dracut is being executed from a live or rescue
> environment. In such cases an incorrect root= could be included in the
> embedded kernel command line which could lead to boot failure.
>
> To prevent this behaviour from causing such unpleasant surprises, a
> check was added to sys-kernel/installkernel to detect whether the
> kernel was being installed from chroot and if Dracut was configured
> to include an embedded kernel command line (hostonly_cmdline=yes).
> While this check prevents boot failures, it also has the unfortunate
> side effect of creating a hard error that is triggered by default on
> new Gentoo installs. This has proven to be a significant stumbling
> block that new users often trip over. For this reason it was decided
> to disable the hostonly_cmdline setting in Gentoo's default settings
> for Dracut.
>
> <<<SNIP>>>
> User Action Required (GRUB)
> ====================
>
> Users booting with GRUB should compare the GRUB_CMDLINE_LINUX and
> GRUB_CMDLINE_LINUX_DEFAULT settings in /etc/default/grub against the
> kernel command line embedded in the initramfs or
> Unified Kernel Image (UKI). The lsinitrd utility provided by
> sys-kernel/dracut can be used for this purpose. For example, in the
> case of a plain initramfs:
>
> lsinitrd /boot/initramfs-x.y.z-gentoo-dist.img
>
> Or, in the case of an Unified Kernel Image:
> lsinitrd /boot/vmlinuz-x.y.z-gentoo-dist.efi
>
> The final lines of the output of these commands show which kernel
> parameters are embedded in the Dracut initramfs. For example:
>
> dracut cmdline:
> ro
>
> If kernel parameters that are essential for successfully booting
> the system (such as root=) are present in the "dracut cmdline"
> section but not in /etc/default/grub then user intervention is
> required. In that case please adjust the GRUB_CMDLINE_LINUX or
> GRUB_CMDLINE_LINUX_DEFAULT settings in /etc/default/grub to include
> the missing kernel parameters. After adjustments don't forget to
> update the grub.cfg. For example:
>
> grub-mkconfig -o /boot/grub/grub.cfg
>
> Note that when Secure Boot is enabled the grub.cfg might reside in a
> different directory, for example: /efi/EFI/Gentoo/grub.cfg.

Howdy,

I get that they making a change because when booting from a CD/USB 
stick/whatever, it detects the wrong thing and applies the wrong 
setting.  Sounds like a good idea to change that since this likely 
happens a lot.  However, I get lost on the settings for 
GRUB_CMDLINE_LINUX* of which there are two.  One with a DEFAULT on the 
end as well.  This is my current setting.



root@Gentoo-1 / # cat /etc/default/grub | grep  GRUB_CMDLINE_LINUX
GRUB_CMDLINE_LINUX="video=efifb:on nvidia_drm.modeset=1 
nvidia-drm.fbdev=1 ibt=off"
#GRUB_CMDLINE_LINUX_DEFAULT=""
root@Gentoo-1 / #



I've never needed to enable the DEFAULT one so it is commented out.  
Should I uncomment that line?  Should I put in that it is the same as 
the other setting?  Leave it as is?

Also, for the dracut cmdline command, I get this.



root@Gentoo-1 / # dracut cmdline
dracut[E]: i18n_vars not set!  Please set up i18n_vars in configuration 
file.
root@Gentoo-1 / #


If I read the news item corrent, that isn't right.  It should spit out 
something like this:  video=efifb:on nvidia_drm.modeset=1 
nvidia-drm.fbdev=1 ibt=off or just ro like in the news item.  Am I 
understanding this right?  Am I wrong on this?  No idea on the i18n 
thingy.  o_O

Thanks.

Dale

:-)  :-)

P. S.  Heads up users.  This change is coming and if you use Grub, you 
better check yours.  It says it could cause your system not to boot.  I 
tend to run default settings here and I bet a LOT of others do as well.