[RFC] initoverlayfs - a scalable initial filesystem

[Eric Curtin]

On Sat, 9 Dec 2023 at 14:56, Andrei Borzenkov <arvidjaar at gmail.com> wrote:
>
> On 09.12.2023 17:42, Eric Curtin wrote:
> > On Sat, 9 Dec 2023 at 12:46, Luca Boccassi <bluca at debian.org> wrote:
> >>
> >> On Fri, 8 Dec 2023 at 19:00, Eric Curtin <ecurtin at redhat.com> wrote:
> >>>
> >>> We have been working on a new initial filesystem called initoverlayfs.
> >>> It is a new filesystem that provides a more scalable approach to
> >>> initial filesystems as opposed to just using initrds. We are writing
> >>> this RFC to the systemd and dracut mailing lists (feel free to forward
> >>> to UAPI group also) because although this solution works without
> >>> changing the code in these projects, it operates in the same area as
> >>> systemd, udev, dracut, etc. and uses these tools.
> >>
> >> It seems to me everything you described already exists? If you want to
> >> avoid having an initrd -> rootfs transition, you can already do that -
> >
> > You need a initrd -> rootfs transition for generic linux operating
> > systems right?
>
> No, you do not. Nothing stops you from running off initramfs (today you
> do not really have init*RAM Disk* - the content of initrd is unpacked
> into initramfs.

Apologies if I am misinterpreting this response, I use terms initrd
and initramfs
interchangeably (not technically correct, but it's common to do this). The
point is to avoid unpacking as much as possible, because in many initrds
the majority of the software need not be unpacked, but is designed to work
with throwaway initial filesystems.

>
> > Or else you start building all sorts of things directly
> > into the kernel which isn't really scalable.
> >
>
> See above.
>