• [gentoo-dev] 2025-xx-yy-dracut-hostonly: new news item

    From Nowa Ammerlaan@21:1/5 to All on Fri Jan 24 19:50:02 2025
    To be published whenever the next version of Dracut is released and
    pushed into ::gentoo.

    Upstream has changed the default setting for hostonly in the
    kernel-install hook. I do not expect huge problems, but there might be
    some weirdness on more unusual systems. I do anticipate some confusion
    since the default has only changed in the kernel installation hooks, and
    not when Dracut is invoked directly. I hope that this situation will be resolved in the future, in the meantime this news item should help
    clarify what is going on.

    Enabling hostonly was already our (and upstreams) recommendation on the
    wiki.

    Please let me know if the below is clear.

    See-also: https://github.com/dracut-ng/dracut-ng/pull/1158

    Best regards,
    Nowa


    Title: Dracut changed default for hostonly setting
    Author: Nowa Ammerlaan <nowa@gentoo.org>
    Posted: 2025-xx-yy
    Revision: 1
    News-Item-Format: 2.0
    Display-If-Installed: sys-kernel/installkernel[dracut]

    Dracut is an initramfs generation tool. It may be invoked via the
    installkernel mechanism in order to automatically generate a new
    initramfs when the kernel is installed. If you are reading this then sys-kernel/installkernel is configured to use Dracut and the below is
    relevant for you.

    What changed?
    ====================

    Starting with version 106 of sys-kernel/dracut the default for the
    "hostonly" setting has changed from disabled to enabled when Dracut is
    invoked via installkernel[1].

    "hostonly" is a setting for Dracut that controls how much is included
    in the generated initramfs image. When it is disabled Dracut aims to
    generate an initramfs image that is bootable on any hardware. On the
    other hand, when this setting is enabled, Dracut aims to generate an
    initramfs image containing only what is needed to boot the current
    system. The advantage is a significantly smaller initramfs images,
    but this comes with the cost of losing portability.

    Example: When the "hostonly" setting is disabled, Dracut's drm module
    will cause all GPU drivers to be included in the initramfs. When it is
    enabled, only the drivers for GPUs that are currently present in the
    system are included in the initramfs.

    Enabling the "hostonly" setting was and is our recommendation for most
    use cases. This however was not the default behaviour in versions
    prior to 106.

    Note, the default value for the "hostonly" setting has changed only
    when Dracut is invoked via installkernel. Disabled remains the default behaviour when Dracut is invoked directly.

    User Action Required
    ====================

    If your system is already configured to enable "hostonly" setting via /etc/dracut.conf.d/ then effectively nothing has changed for you.

    However, if Dracut has previously not been configured to enable the
    "hostonly" setting, then starting with version 106 the behaviour of
    Dracut will change for you. Though we do not expect major problems, we recommend ensuring a backup booting option remains available before
    rebooting the system after the first kernel upgrade following the
    upgrade of Dracut. This is usually the case unless the old kernels are
    manually removed by the user.

    If you do experience a booting problem with the "hostonly" enabled
    initramfs images, then please report this problem to Dracut[2].

    The "hostonly" setting may be disabled via /etc/dracut.conf.d/
    configuration snippets. For example:

    echo "hostonly=no" >> /etc/dracut.conf.d/95-no-hostonly.conf


    [1] https://github.com/dracut-ng/dracut-ng/pull/1158
    [2] https://github.com/dracut-ng/dracut-ng/issues

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