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+--- Thread: Enabling overlayfs/DTO (/showthread.php?tid=11829)
Enabling overlayfs/DTO - soupy - 10-14-2020
Hi,
I'm having some trouble enabling overlayfs on my board. It's running vanilla mainline Linux with just a couple patches for emmc.
I have configfs and overlayfs enabled, but the device-tree directory doesn't populate in /sys/kernel/config.
My understanding of overlayfs is a bit hazy, so I'm confused whether this device-tree directory is provided by a separate driver or patchset found in the ayufan kernel, or if it needs to be mounted manually. This guide that I was following shows that the directory is automatically found in /sys/kernel/config when it's mounted, again not sure if that feature is provided by the custom kernel they are using...
In terms of mounting, I am pretty confused by the documentation in https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt.
RE: Enabling overlayfs/DTO - sigmaris - 10-22-2020
"overlayfs" is different from support for device tree overlays; overlayfs is used to build up a filesystem from several overlayed layers, e.g. when building up a Docker container filesystem from layers in the image.
It sounds like what you are looking for is dynamic device tree overlay support configured via configfs. For that you need a patched kernel as the patches for this are not in mainline Linux. The patches are included in some kernel trees, e.g. the Raspberry Pi kernel and Ayufan's mainline kernel tree (the top three commits here: https://github.com/ayufan-rock64/linux-mainline-kernel/commits/771fbfe3488c43acfe9fd4be33b78c13afa0059c )