[systemd-devel] Exploring Minimal Systemd in Initramfs for Faster Boot

[Mantas Mikulėnas]

On Mon, Sep 23, 2024 at 12:33 PM <Dharma.B at microchip.com> wrote:

> Hi Team,
>
> I'm exploring the possibility of splitting the systemd binary to
> optimize boot time before and after switching to the root filesystem.
>
> I’m aware that the systemd binary is quite large and may not fit in the
> initramfs, but is it feasible to have a minimal version of systemd that
> can invoke essential services and continue tracking them after
> transitioning to the main root filesystem?
>

Unless I missed any recent changes, transitioning to the main root
filesystem always involves launching the main systemd executable anew from
rootfs (even if the initramfs was already running systemd). It's fine if a
minimal initramfs-systemd execs a larger rootfs-systemd during the
transition as long as their versions are compatible – though I am not sure
if there is actually any state handed over between them in the first place;
IIRC normally none of the initramfs services are expected to survive the
transition.

-- 
Mantas Mikulėnas
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