binman: Add support for sections
It is useful to be able to split an image into multiple sections,
each with its own size and position, for cases where a flash device has
read-only and read-write portions.
Add support for this.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/README b/tools/binman/README
index 196dda1..5ef1246 100644
--- a/tools/binman/README
+++ b/tools/binman/README
@@ -392,6 +392,45 @@
different name for each and specifying the type with the 'type' attribute.
+Sections and hiearchical images
+-------------------------------
+
+Sometimes it is convenient to split an image into several pieces, each of which
+contains its own set of binaries. An example is a flash device where part of
+the image is read-only and part is read-write. We can set up sections for each
+of these, and place binaries in them independently. The image is still produced
+as a single output file.
+
+This feature provides a way of creating hierarchical images. For example here
+is an example with two copies of U-Boot. One is read-only (ro), intended to be
+written only in the factory. Another is read-write (rw), so that it can be
+upgraded in the field. The sizes are fixed so that the ro/rw boundary is known
+and can be programmed:
+
+ binman {
+ section@0 {
+ read-only;
+ size = <0x100000>;
+ u-boot {
+ };
+ };
+ section@1 {
+ size = <0x100000>;
+ u-boot {
+ };
+ };
+ };
+
+This image could be placed into a SPI flash chip, with the protection boundary
+set at 1MB.
+
+A few special properties are provided for sections:
+
+read-only:
+ Indicates that this section is read-only. This has no impact on binman's
+ operation, but his property can be read at run time.
+
+
Special properties
------------------
@@ -586,8 +625,6 @@
- Allow easy building of images by specifying just the board name
- Produce a full Python binding for libfdt (for upstream)
- Add an option to decode an image into the constituent binaries
-- Suppoort hierarchical images (packing of binaries into another binary
- which is then placed in the image)
- Support building an image for a board (-b) more completely, with a
configurable build directory
- Consider making binman work with buildman, although if it is used in the