CODEWITHSUNDEEP
squashfsinitramfs
c_spk
c_spk

Reputation: 179

OverlayFS as root FS: should I mount --move upper/lower/workdir to new root?

I work on an embedded system which boots from a SquashFS image located on a UBIFS formatted SPI flash. I added OverlayFS over / (root) support so that we can change all the files around but get them reset after reboot. All the OverlayFS magic is performed in initramfs. When setting up all the mountpoints, I mount --move /run and the UBIFS flash partition. I want to know whether I should mount --move the upper/lower/workdir of the OverlayFS to the new root too before switch_root. It does seem to work without it, but once in a while I get spontaneous reboots and a bus error on a manual reboot.

Upvotes: 0

Views: 2170

Answers (1)

oliver
oliver

Reputation: 811

What tools do you have in your initramfs? Why not use busybox's switch_root or klibc's run-init, which does all the needed moving (from what I gather [0] [1])?

So to answer your question, by using the right tool, you not need to worry about using mount --move at all. If you insist however on manually doing it, do what these tools do.

[0] http://man7.org/linux/man-pages/man8/switch_root.8.html

[1] https://git.busybox.net/busybox/tree/klibc-utils/run-init.c

Upvotes: 0

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