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

Michael <[email protected]> Thu, 07 May 2026 11:59:01 +0100
Newsgroups	gmane.linux.gentoo.user
Message-ID	<14008215.uLZWGnKmhe@rogueboard>
On Wednesday, 6 May 2026 20:58:21 British Summer Time Dale wrote:
> 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.

According to GRUB manual[1] the GRUB_CMDLINE_LINUX should contain the 
common options you want your normal kernel to boot with.  The 
GRUB_CMDLINE_LINUX_DEFAULT includes additional options for your recovery 
kernel.  These will be appended by GRUB at the end of the normal 
GRUB_CMDLINE_LINUX list of options.

https://www.gnu.org/software/grub/manual/grub/grub.html
signature.asc (application/pgp-signature, 870 B)