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| author | Michael Tretter <m.tretter@pengutronix.de> | 2019-10-18 15:14:35 +0200 |
|---|---|---|
| committer | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2019-10-29 11:24:19 +0100 |
| commit | 09ee387e082f3bffe671d76356191e726132b6ef (patch) | |
| tree | 964be6bab2758d2a1aec3ef1ea7fa8206f5b7b97 | |
| parent | 228ae7ff11874493054b32879807d1392912a0ea (diff) | |
| download | systemd-09ee387e082f3bffe671d76356191e726132b6ef.tar.gz | |
boot-loader-spec: add devicetree-overlay key
Device tree overlays are a convenient way to patch device trees, e.g.,
add new devices to a device tree or enable/disable devices. This is
useful for non-discoverable but configurable hardware. Device tree
overlays are commonly used for displays on the Raspberry Pi or for
describing the content of FPGA bitstreams.
Add the devicetree-overlay key to boot loader specification entries to
allow boot loaders to apply overlays.
See #13537
| -rw-r--r-- | docs/BOOT_LOADER_SPECIFICATION.md | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/docs/BOOT_LOADER_SPECIFICATION.md b/docs/BOOT_LOADER_SPECIFICATION.md index 55a9fef4be..3bd300c24e 100644 --- a/docs/BOOT_LOADER_SPECIFICATION.md +++ b/docs/BOOT_LOADER_SPECIFICATION.md @@ -112,6 +112,12 @@ These configuration snippets shall be Unix-style text files (i.e. line separatio * `devicetree` refers to the binary device tree to use when executing the kernel. This also shall be a path relative to the `$BOOT` directory. This key is optional. Example: `6a9857a393724b7a981ebb5b8495b9ea/3.8.0-2.fc19.armv7hl/tegra20-paz00.dtb`. +* `devicetree-overlay` refers to a list of device tree overlays that should be +applied by the boot loader. Multiple overlays are separated by spaces and +applied in the same order as they are listed. This key is optional but depends +on the `devicetree` key. Example: +`/6a9857a393724b7a981ebb5b8495b9ea/overlays/overlay_A.dtbo +/6a9857a393724b7a981ebb5b8495b9ea/overlays/overlay_B.dtbo` * `architecture` refers to the architecture this entry is defined for. The argument should be an architecture identifier, using the architecture vocabulary defined by the EFI specification (i.e. `IA32`, `x64`, `IA64`, `ARM`, `AA64`, …). If specified and this does not match (case insensitively) the local system architecture this entry should be hidden. Each configuration drop-in snippet must include at least a `linux` or an `efi` key and is otherwise not valid. Here's an example for a complete drop-in file: |