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

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Hi,

I've tested the GRUB upgrade path on a live system using the live ebuild
and found no issues with them.

I also did the same with a fresh install and enjoyed a much easier time
installing.

I think my only recommendation after trying this, is that we order the
steps the same way the handbook presents these options.
I'm not sure if it's important, I just think it will help quickly find the right
steps.

So the new ordering would go GRUB, systemd-boot, refied and other.

No opinions on dealing with UKI positions.

Thanks for doing this!

immolo

On Sat, 2 May 2026 at 13:59, Nowa Ammerlaan <nowa@gentoo.org> wrote:
>
> On 02/05/2026 14:52, Nowa Ammerlaan wrote:
> > Hi Team,
> >
> > This is the first draft of a news item to accompany the next release of
> > sys-kernel/dracut (111) which will change the default value of the
> > hostonly_cmdline setting. I have tried to keep a logical flow from the
> > specific to the general which I hope will help users find which specific
> > instructions are relevant for them. There might still be room for
> > improvement here though, this is a rather complicated one because of the
> > large variation in setups. Anyway, let me know what you think.
> >
> > Best regards,
> > Nowa
> >
> Sorry, I messed up the copy-paste somehow, here's the proper version:
>
> Title: Dracut changed default for hostonly_cmdline setting
> Author: Nowa Ammerlaan <nowa@gentoo.org>
> 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.
>
> User Action Required (all users)
> ====================
>
> When upgrading to Dracut version 111, a sanity check should be
> performed to ensure that kernel parameters required to boot
> successfully are still present in the kernel command line. When in
> doubt, ensure a system rescue CD or USB is close at hand. More
> specific instructions for various setups follow below, ordered from
> the specific to the more general.
>
> As always, do not hesitate to use our support channels to ask for
> clarification or assistance.
>
> User Action Required (Systemd GPT Auto Generator)
> ====================
>
> Systems that utilise the Systemd GPT Auto Generator mechanism to
> automatically detect and find the root partition at boot should not
> require any manual intervention. Though, before rebooting, users
> should verify that the GPT Auto Generator is actually being used and
> is working properly. To do so, check that /dev/gpt-auto-root currently
> exists and points to your root partition. For example:
>
> ls -l /dev/gpt-auto-root
>
> Should produce an output similar to the below if /dev/nvme0n1p1 is the
> root partition:
>
> lrwxrwxrwx 1 root root 4 May  2 10:33 /dev/gpt-auto-root -> nvme0n1p1
>
> If this is not the case then proceed with the instructions below that
> best match the setup to ensure that the root partition is set on the
> kernel command line using an alternative method.
>
> User Action Required (Generic Unified Kernel Image: "generic-uki")
> ====================
>
> Users booting with the generic Unified Kernel Image (USE=generic-uki)
> functionality provided by the distribution kernels (dist-kernel) do
> not have to take any action as the hostonly_cmdline is already
> disabled in these builds:
> - sys-kernel/vanilla-kernel[generic-uki]
> - sys-kernel/gentoo-kernel[generic-uki]
> - sys-kernel/gentoo-kernel-bin[generic-uki]
>
> User Action Required (Unified Kernel Image with Secure Boot)
> ====================
>
> Booting a Unified Kernel Image (UKI) with Secure Boot enabled is a
> special case because in this situation the kernel command line
> supplied by the bootloader or the firmware is ignored and the built-in
> UKI command line, along with the parameters embedded in the initramfs,
> take precedence. The instructions below are also relevant if no
> kernel command line is set by the bootloader or the firmware.
>
> An easy way to check the built-in kernel command line of an UKI is to
> use the lsinitrd tool provided by sys-kernel/dracut. For example:
>
> lsinitrd /efi/EFI/Linux/gentoo-x.y.z-gentoo-dist.efi
>
> This command will produce an output that could contain for example:
>
> <snip>
> Command line:
> quiet
> splash
> root=PARTUUID=7ae430c6-07e8-3b4e-a796-b2a28706b3fb
> <snip>
> dracut cmdline:
> ro
>
> Showing that the built-in kernel command line for this UKI contains
> "quiet", "splash" and sets the root partition to the partition that
> has the partition UUID "7ae430c6-07e8-3b4e-a796-b2a28706b3fb".
> Additionally, the kernel command line embedded in the initramfs
> contains "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 the "Command line" section then user intervention
> is required. In that case please adjust the configuration of the
> UKI generator to include the appropriate kernel parameters in the
> built-in UKI command line.
>
> If Ukify (sys-apps/systemd[ukify] or sys-apps/systemd-utils[ukify])
> is generating the UKI then adjust the "Cmdline=" setting in
> /etc/kernel/uki.conf. If that setting is not present in the uki.conf
> then adjust the kernel command line in /etc/kernel/cmdline.
>
> If Dracut itself is generating the UKI then please set or adjust the
> "kernel_cmdline=" setting in a dracut configuration file in
> /etc/dracut.conf.d/.
>
> If unsure which tool is generating the UKI then please inspect the
> current value of "uki_generator" in /usr/lib/kernel/install.conf and
> /etc/kernel/cmdline.
>
> User Action Required (systemd-boot)
> ====================
>
> Users booting with systemd-boot should compare the contents of
> /etc/kernel/cmdline against the kernel command line embedded in the
> initramfs or Unified Kernel Image (UKI). If Unified Kernel Images are
> used and the /etc/kernel/cmdline file is empty or missing then no
> kernel command line is set by systemd-boot, in this case please refer
> to the "Unified Kernel Image with Secure Boot" section above, even if
> Secure Boot is not enabled.
>
> The lsinitrd utility provided by sys-kernel/dracut can be used to
> inspect the kernel parameters embedded in an initramfs or UKI. For
> example, in the case of a plain initramfs:
>
> lsinitrd /efi/gentoo/x.y.z-gentoo-dist/initrd
>
> Or, in the case of an Unified Kernel Image:
> lsinitrd /efi/EFI/Linux/gentoo-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/kernel/cmdline then user intervention is
> required. In that case please adjust /etc/kernel/cmdline to include
> the missing kernel parameters.
>
> 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.
>
> User Action Required (rEFInd)
> ====================
>
> Users booting with rEFInd should compare kernel command line set
> in the refind_linux.conf file against the kernel command line embedded
> in the initramfs or Unified Kernel Image (UKI). The refind_linux.conf
> configuration file usually resides in /boot but may also be found
> elsewhere. If Unified Kernel Images are used and the refind_linux.conf
> configuration file is empty or missing then no kernel command line is
> set by rEFInd, in this case please refer to the "Unified Kernel Image
> with Secure Boot" section above, even if Secure Boot is not enabled.
>
> The lsinitrd utility provided by sys-kernel/dracut can be used to
> inspect the kernel parameters embedded in an initramfs or UKI. 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 the refind_linux.conf then user intervention is
> required. In that case please adjust refind_linux.conf to include the
> missing kernel parameters.
>
> User Action Required (other/general)
> ====================
>
> For other setups please refer to the wiki page or manual of your
> bootloader and find where the kernel command line is set. Then
> compare this setting with the kernel parameters embedded in the
> initramfs. If essential parameters are present in the later but not in
> the former, then please move those parameters to your bootloader's
> configuration. When Unified Kernel Images are used then also consider
> the built-in UKI command line set by the UKI generator. Note that when
> Secure Boot is disabled, the bootloader may override the built-in UKI
> command line. However, when Secure Boot is enabled then any parameters
> set by the bootloader are ignored and the built-in UKI command line is
> always used.
>
> See Also
> ====================
>
> [1] https://github.com/dracut-ng/dracut-ng/pull/2399
> [2] https://bugs.gentoo.org/971572
>
>

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Re: [gentoo-dev] New News Item: 2026-xx-yy-dracut-hostonly-cmdline Nowa Ammerlaan <nowa@gentoo.org> - 2026-05-02 15:00 +0200
  Re: [gentoo-dev] New News Item: 2026-xx-yy-dracut-hostonly-cmdline Immolo <immoloism@googlemail.com> - 2026-05-06 20:50 +0200
  Re: [gentoo-dev] New News Item: 2026-xx-yy-dracut-hostonly-cmdline Sam James <sam@gentoo.org> - 2026-05-07 02:30 +0200

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