fdt: Add support for a separate device tree (CONFIG_OF_SEPARATE)
This adds support for an FDT to be build as a separate binary file called
u-boot.dtb. This can be concatenated with the U-Boot binary to provide a
device tree located at run-time by U-Boot. The Makefile is modified to
provide this file in u-boot-dtb.bin.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/README b/README
index 094869c..558f011 100644
--- a/README
+++ b/README
@@ -824,8 +824,8 @@
experimental and only available on a few boards. The device
tree is available in the global data as gd->fdt_blob.
- U-Boot needs to get its device tree from somewhere. At present
- the only way is to embed it in the image with CONFIG_OF_EMBED.
+ U-Boot needs to get its device tree from somewhere. This can
+ be done using one of the two options below:
CONFIG_OF_EMBED
If this variable is defined, U-Boot will embed a device tree
@@ -834,6 +834,18 @@
is then picked up in board_init_f() and made available through
the global data structure as gd->blob.
+ CONFIG_OF_SEPARATE
+ If this variable is defined, U-Boot will build a device tree
+ binary. It will be called u-boot.dtb. Architecture-specific
+ code will locate it at run-time. Generally this works by:
+
+ cat u-boot.bin u-boot.dtb >image.bin
+
+ and in fact, U-Boot does this for you, creating a file called
+ u-boot-dtb.bin which is useful in the common case. You can
+ still use the individual files if you need something more
+ exotic.
+
- Watchdog:
CONFIG_WATCHDOG
If this variable is defined, it enables watchdog