nullfs?

Posted Feb 13, 2026 20:21 UTC (Fri) by chexo4 (guest, #169500)
Parent article: The first half of the 7.0 merge window

I’m confused what the point of nullfs is. I thought most init scripts worked by doing pivot root already anyway, why would you need to clean up the initramfs in that case?

Are files from the previous rootfs present after a pivot??

nullfs?

Posted Feb 14, 2026 12:50 UTC (Sat) by zhalas (subscriber, #114013) [Link]

> I’m confused what the point of nullfs is. I thought most init scripts worked by doing pivot root already anyway, why would you need to clean up the initramfs in that case?

pivot_root does not work on rootfs, (see: https://man7.org/linux/man-pages/man2/pivot_root.2.html):

> EINVAL The current root is on the rootfs (initial ramfs) mount;
> see NOTES.

> The rootfs (initial ramfs) cannot be pivot_root()ed. The
> recommended method of changing the root filesystem in this case is
> to delete everything in rootfs, overmount rootfs with the new
> root, attach stdin/stdout/stderr to the new /dev/console, and exec
> the new init(1). Helper programs for this process exist; see
> switch_root(8).
```

see: https://man7.org/linux/man-pages/man2/pivot_root.2.html