OverlayFS and its use in Yocto Project
summary
OverlayFS redirects writes from a read‑only root to an upper layer so configurations survive A/B updates while the device sees the original paths, but the upper layer must support xattrs and its workdir must live on the same filesystem. Yocto support comes via recipes like volatile-binds, an overlayfs class (systemd only) and overlayfs-etc for early /etc remounting. Online changes are undefined, NFS upper layers aren’t supported, kernel feature bits must be off for updates (bugfix landed in 5.15), and tools include overlayfs-progs, overlayfs-tools and xfstests.
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chapters (7)
- 0:00Start
- 0:55Partition layout of embedded device
- 2:05Application write access (part 3)
- 5:45Terminology
- 8:45Overlay FS file removal
- 9:31Overlay FS directory handling (part 2)
- 12:20Kernel configuration (part 2)
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