[PATCH 5/7] doc: move 'Reproducible builds'

[Heinrich Schuchardt]

Move the README section to the HTML documentation.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
---
 README                     | 11 -----------
 doc/build/index.rst        |  1 +
 doc/build/reproducible.rst | 25 +++++++++++++++++++++++++
 3 files changed, 26 insertions(+), 11 deletions(-)
 create mode 100644 doc/build/reproducible.rst

diff --git a/README b/README
index a969fc7a97..48db535556 100644
--- a/README
+++ b/README
@@ -1713,17 +1713,6 @@ This firmware often needs to be loaded during U-Boot booting.
 - CONFIG_SYS_MC_RSV_MEM_ALIGN
 	Define alignment of reserved memory MC requires
 
-Reproducible builds
--------------------
-
-In order to achieve reproducible builds, timestamps used in the U-Boot build
-process have to be set to a fixed value.
-
-This is done using the SOURCE_DATE_EPOCH environment variable.
-SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
-option for U-Boot or an environment variable in U-Boot.
-
-SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
 
 Building the Software:
 ======================
diff --git a/doc/build/index.rst b/doc/build/index.rst
index dc9cde4001..64e66491bd 100644
--- a/doc/build/index.rst
+++ b/doc/build/index.rst
@@ -9,6 +9,7 @@ Build U-Boot
    source
    gcc
    clang
+   reproducible
    docker
    tools
    buildman
diff --git a/doc/build/reproducible.rst b/doc/build/reproducible.rst
new file mode 100644
index 0000000000..5423080633
--- /dev/null
+++ b/doc/build/reproducible.rst
@@ -0,0 +1,25 @@
+Reproducible builds
+===================
+
+In order to achieve reproducible builds, timestamps used in the U-Boot build
+process have to be set to a fixed value.
+
+This is done using the SOURCE_DATE_EPOCH environment variable which specifies
+the number of seconds since 1970-01-01T00:00:00Z.
+
+Example
+-------
+
+To build the sandbox with 2023-01-01T00:00:00Z as timestamp we can use:
+
+.. code-block:: bash
+
+    make sandbox_defconfig
+    SOURCE_DATE_EPOCH=1672531200 make
+
+This date is shown when we launch U-Boot:
+
+.. code-block:: console
+
+    ./u-boot -T
+    U-Boot 2023.01 (Jan 01 2023 - 00:00:00 +0000)
-- 
2.38.1