From ac93c4534fab65e2cb9ee18164c98d247eea844f Mon Sep 17 00:00:00 2001 From: Kaustabh Chakraborty Date: Tue, 3 Feb 2026 18:38:44 +0530 Subject: doc: board: samsung: exynos-mobile: add DEVICE_TREE make flag in build Since there is only one internal device tree allowed in U-Boot, the DEVICE_TREE flag is required for building images for various devices. Document it in the build guide. Signed-off-by: Kaustabh Chakraborty Signed-off-by: Minkyu Kang --- doc/board/samsung/exynos-mobile.rst | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'doc') diff --git a/doc/board/samsung/exynos-mobile.rst b/doc/board/samsung/exynos-mobile.rst index 37718af1fea..d0173b1f8cb 100644 --- a/doc/board/samsung/exynos-mobile.rst +++ b/doc/board/samsung/exynos-mobile.rst @@ -25,12 +25,13 @@ If a cross-compiler is required, install it and set it up like so: export CROSS_COMPILE=aarch64-linux-gnu- -Then, run the following commands to build U-Boot: +Then, run the following commands to build U-Boot (replace ```` with the +upstream DTB path for the target device): .. prompt:: bash $ make O=.output exynos-mobile_defconfig - make O=.output -j$(nproc) + make DEVICE_TREE= O=.output -j$(nproc) If successful, the U-Boot binary will be present in ``.output/u-boot.bin``. -- cgit v1.2.3 From be1b1cd641f058a19d2ec5e1ab3bb4d81a3e1e78 Mon Sep 17 00:00:00 2001 From: Kaustabh Chakraborty Date: Tue, 3 Feb 2026 18:38:45 +0530 Subject: doc: board: samsung: exynos-mobile: use u-boot-nodtb.bin for packaging process U-Boot for this board is programmed to use the external DTB if an internal device tree is not available. This makes it safe to build boot images using the non-DTB U-Boot binary, while taking up less space. Reflect this change in documentation. Signed-off-by: Kaustabh Chakraborty Signed-off-by: Minkyu Kang --- doc/board/samsung/exynos-mobile/exynos7870.rst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'doc') diff --git a/doc/board/samsung/exynos-mobile/exynos7870.rst b/doc/board/samsung/exynos-mobile/exynos7870.rst index bbd857580b8..37562e272b4 100644 --- a/doc/board/samsung/exynos-mobile/exynos7870.rst +++ b/doc/board/samsung/exynos-mobile/exynos7870.rst @@ -53,7 +53,7 @@ Finally, use ``mkbootimg`` by osm0sis [3]_ to generate the boot image: .. prompt:: bash $ mkbootimg -o u-boot.img \ - --kernel .output/u-boot.bin \ + --kernel .output/u-boot-nodtb.bin \ --dt stub-dt.img Offsets are not provided to ``mkbootimg`` as S-BOOT ignores them. -- cgit v1.2.3 From 11198fa347390eb449c2a0939f5f00cf510fe285 Mon Sep 17 00:00:00 2001 From: Kaustabh Chakraborty Date: Tue, 3 Feb 2026 18:38:49 +0530 Subject: doc: board: samsung: exynos-mobile: remove requirement of stub device tree Flashing U-Boot for Exynos 7870 requires creating a stub device tree, where certain properties and nodes are defined which are populated by the previous bootloader in the phones. Since these properties are now available in the U-Boot device tree, it's now possible to use the same blob generated by U-Boot in place of the stub, when creating boot images. Update the build documentation to reflect the same. Signed-off-by: Kaustabh Chakraborty Signed-off-by: Minkyu Kang --- doc/board/samsung/exynos-mobile/exynos7870.rst | 40 ++------------------------ 1 file changed, 3 insertions(+), 37 deletions(-) (limited to 'doc') diff --git a/doc/board/samsung/exynos-mobile/exynos7870.rst b/doc/board/samsung/exynos-mobile/exynos7870.rst index 37562e272b4..702b21244eb 100644 --- a/doc/board/samsung/exynos-mobile/exynos7870.rst +++ b/doc/board/samsung/exynos-mobile/exynos7870.rst @@ -6,47 +6,13 @@ Samsung Exynos 7870 Boards Preparation ----------- -Create the following device tree (named ``stub.dts``) -.. code-block:: devicetree - - /dts-v1/; - - / { - compatible = "samsung,exynos7870"; - #address-cells = <2>; - #size-cells = <1>; - - model_info-chip = <7870>; - model_info-hw_rev = <0>; - model_info-hw_rev_end = <255>; - - chosen { - }; - - memory@80000000 { - device_type = "memory"; - reg = <0x0 0x80000000 0x0>; - }; - - memory@100000000 { - device_type = "memory"; - reg = <0x1 0x00000000 0x0>; - }; - }; - -The chosen node and memory ranges are populated by S-BOOT. A certain device -model may have multiple variants, with differing amounts of RAM and storage. The -RAM capacity information is graciously provided by S-BOOT's device tree -overlays. - -Compile it to a device tree blob, then pack it in the QCDT format [1]_ using -``dtbTool-exynos`` [2]_ by issuing the following commands: +Pack the device tree blob in the QCDT format [1]_ using ``dtbTool-exynos`` [2]_ +by issuing the following commands: .. prompt:: bash $ - dtc -I dts -O dtb -o stub.dtb stub.dts - dtbTool-exynos -o stub-dt.img stub.dtb + dtbTool-exynos -o stub-dt.img .output/u-boot.dtb Finally, use ``mkbootimg`` by osm0sis [3]_ to generate the boot image: -- cgit v1.2.3