doc: sl-mx8mm: Add CROSS_COMPILE to U-Boot make call and improve comment

Add the CROSS_COMPILE flag as we assume we build in a cross environment.
Also improve the comment about copying the binary to SD card.

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>

diff --git a/doc/board/kontron/sl-mx8mm.rst b/doc/board/kontron/sl-mx8mm.rst
index 8b29cbba67b4a25811870dc252080b323c122dbe..702db60fe388182cb30e9ca8dc9f5c2f3d3dd2d5 100644 (file)
--- a/doc/board/kontron/sl-mx8mm.rst
+++ b/doc/board/kontron/sl-mx8mm.rst
@@ -81,9 +81,9 @@ Build U-Boot
 .. code-block:: bash
 
    $ make kontron-sl-mx8mm_defconfig
-   $ make
+   $ make CROSS_COMPILE=aarch64-linux-gnu-
 
-Burn the flash.bin to SD card at an offset of 33 KiB:
+Copy the flash.bin to SD card at an offset of 33 KiB:
 
 .. code-block:: bash