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authorJulius Werner <jwerner@chromium.org>2019-07-24 19:37:56 -0700
committerTom Rini <trini@konsulko.com>2019-07-29 09:32:08 -0400
commit18cfa612a9f80249062297befbca7dfa90264622 (patch)
treec9db0147d292b255f8f499afdc75d21a2713b593 /doc
parentb1307f884a913f52a201491053b6d221c4204f60 (diff)
downloadu-boot-18cfa612a9f80249062297befbca7dfa90264622.tar.gz
fit: Support compat string property in configuration node
This patch adds support for an optional optimization to compatible string matching where the compatible string property from the root node of the kernel FDT can be copied into the configuration node of the FIT image. This is most useful when using compressed FDTs or when using FDT overlays, where the traditional extraction of the compatible string from the kernel FDT itself is not easily possible. Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'doc')
-rw-r--r--doc/uImage.FIT/kernel_fdts_compressed.its73
-rw-r--r--doc/uImage.FIT/source_file_format.txt7
2 files changed, 80 insertions, 0 deletions
diff --git a/doc/uImage.FIT/kernel_fdts_compressed.its b/doc/uImage.FIT/kernel_fdts_compressed.its
new file mode 100644
index 0000000000..8f81106efc
--- /dev/null
+++ b/doc/uImage.FIT/kernel_fdts_compressed.its
@@ -0,0 +1,73 @@
+/*
+ * U-Boot uImage source file with a kernel and multiple compressed FDT blobs.
+ * Since the FDTs are compressed, configurations must provide a compatible
+ * string to match directly.
+ */
+
+/dts-v1/;
+
+/ {
+ description = "Image with single Linux kernel and compressed FDT blobs";
+ #address-cells = <1>;
+
+ images {
+ kernel {
+ description = "Vanilla Linux kernel";
+ data = /incbin/("./vmlinux.bin.gz");
+ type = "kernel";
+ arch = "ppc";
+ os = "linux";
+ compression = "gzip";
+ load = <00000000>;
+ entry = <00000000>;
+ hash-1 {
+ algo = "crc32";
+ };
+ hash-2 {
+ algo = "sha1";
+ };
+ };
+ fdt@1 {
+ description = "Flattened Device Tree blob 1";
+ data = /incbin/("./myboard-var1.dtb");
+ type = "flat_dt";
+ arch = "ppc";
+ compression = "gzip";
+ hash-1 {
+ algo = "crc32";
+ };
+ hash-2 {
+ algo = "sha1";
+ };
+ };
+ fdt@2 {
+ description = "Flattened Device Tree blob 2";
+ data = /incbin/("./myboard-var2.dtb");
+ type = "flat_dt";
+ arch = "ppc";
+ compression = "lzma";
+ hash-1 {
+ algo = "crc32";
+ };
+ hash-2 {
+ algo = "sha1";
+ };
+ };
+ };
+
+ configurations {
+ default = "conf@1";
+ conf@1 {
+ description = "Boot Linux kernel with FDT blob 1";
+ kernel = "kernel";
+ fdt = "fdt@1";
+ compatible = "myvendor,myboard-variant1";
+ };
+ conf@2 {
+ description = "Boot Linux kernel with FDT blob 2";
+ kernel = "kernel";
+ fdt = "fdt@2";
+ compatible = "myvendor,myboard-variant2";
+ };
+ };
+};
diff --git a/doc/uImage.FIT/source_file_format.txt b/doc/uImage.FIT/source_file_format.txt
index d701b9bb76..f8e27ed34e 100644
--- a/doc/uImage.FIT/source_file_format.txt
+++ b/doc/uImage.FIT/source_file_format.txt
@@ -240,6 +240,7 @@ o config-1
|- fdt = "fdt sub-node unit-name" [, "fdt overlay sub-node unit-name", ...]
|- fpga = "fpga sub-node unit-name"
|- loadables = "loadables sub-node unit-name"
+ |- compatible = "vendor,board-style device tree compatible string"
Mandatory properties:
@@ -263,6 +264,12 @@ o config-1
of strings. U-Boot will load each binary at its given start-address and
may optionaly invoke additional post-processing steps on this binary based
on its component image node type.
+ - compatible : The root compatible string of the U-Boot device tree that
+ this configuration shall automatically match when CONFIG_FIT_BEST_MATCH is
+ enabled. If this property is not provided, the compatible string will be
+ extracted from the fdt blob instead. This is only possible if the fdt is
+ not compressed, so images with compressed fdts that want to use compatible
+ string matching must always provide this property.
The FDT blob is required to properly boot FDT based kernel, so the minimal
configuration for 2.6 FDT kernel is (kernel, fdt) pair.