doc: bootstd: Describe the optional extension_overlay_addr environment

Add extension_overlay_addr description to the list of environment
variables that can be useful during the standard boot.

Signed-off-by: Kory Maincent (TI.com) <kory.maincent@bootlin.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

diff --git a/doc/develop/bootstd/overview.rst b/doc/develop/bootstd/overview.rst
index f0d4203..397f6db 100644 (file)
--- a/doc/develop/bootstd/overview.rst
+++ b/doc/develop/bootstd/overview.rst
@@ -252,6 +252,9 @@ Various environment variables are used by standard boot. These allow the board
 to control where things are placed when booting the OS. You should ensure that
 your boards sets values for these.
 
+extension_overlay_addr (needed if extension is used)
+    Address at which to load the extension FDT overlays, e.g. 0x02000000
+
 fdtfile
     Name of the flattened device tree (FDT) file to load, e.g.
     "rockchip/rk3399-rockpro64.dtb"