| Howto use the configfs overlay interface. |
| |
| A device-tree configfs entry is created in /config/device-tree/overlays |
| and and it is manipulated using standard file system I/O. |
| Note that this is a debug level interface, for use by developers and |
| not necessarily something accessed by normal users due to the |
| security implications of having direct access to the kernel's device tree. |
| |
| * To create an overlay you mkdir the directory: |
| |
| # mkdir /config/device-tree/overlays/foo |
| |
| * Either you echo the overlay firmware file to the path property file. |
| |
| # echo foo.dtbo >/config/device-tree/overlays/foo/path |
| |
| * Or you cat the contents of the overlay to the dtbo file |
| |
| # cat foo.dtbo >/config/device-tree/overlays/foo/dtbo |
| |
| The overlay file will be applied, and devices will be created/destroyed |
| as required. |
| |
| To remove it simply rmdir the directory. |
| |
| # rmdir /config/device-tree/overlays/foo |
| |
| The rationale for the dual interface (firmware & direct copy) is that each is |
| better suited to different use patterns. The firmware interface is what's |
| intended to be used by hardware managers in the kernel, while the copy interface |
| make sense for developers (since it avoids problems with namespaces). |
