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This is the Wiki for the U-Boot on Renesas R-Car Gen2 SoCs and boards . Refer to the R-Car page for information about Renesas' R-Car SoC family.

Supported boards

As of U-Boot 2018.05-rc2, the following boards are supported including DM and DT:

Supported boards in U-Boot 2018.05-rc2
Board U-Boot defconfig Update procedure
R8A7790 H2 Stout stout_defconfig Updating U-Boot on Gen2
R8A7791 M2-W Porter porter_defconfig Updating U-Boot on Gen2
R8A7794 E2 Silk silk_defconfig Updating U-Boot on Gen2

Building U-Boot manually

Building U-Boot can be done manually by using the U-Boot sources.


  • ARM cross-compiler is mandatory to build U-Boot.

ARM cross-compiler

Debian and Ubuntu includes an ARM cross-compiler in its standard package feed. You can install it as follows:

apt-get install gcc-arm-linux-gnueabi

Other distributions likely also provide ARM cross-compilers. Consult distro-specific documentation for details.

Obtain U-Boot sources

The preferred method of obtaining U-Boot sources is through git VCS, using git protocol:

git clone git://git.denx.de/u-boot.git

or via HTTP:

git clone http://git.denx.de/u-boot.git

Finally, check out the version of U-Boot that will be used for the build:

cd u-boot
git checkout -b my_working_branch v2018.05-rc2

U-Boot git hosting also provides snapshots.

Prepare build environment

Before building U-Boot for R-Car Gen2 system, the following environment variables need to be configured:

export ARCH=arm
export CROSS_COMPILE=arm-linux-gnueabi-

The later variable must match the prefix of the Aarch64 cross-toolchain installed on your system, the example above is valid for Debian and Ubuntu,

Build U-Boot

The U-Boot sources must be configured for a particular supported platform. List of supported platforms and matching U-Boot defconfigs is available at supported boards.

make y_defconfig

for example to configure U-Boot sources for R8A7791 M2-W Porter board:

make porter_defconfig

Once configured, U-Boot sources can be compiled to produce u-boot.img and u-boot-spl.srec:


To speed up build process, -jN option can be passed to make to start multiple jobs at the same time, this is beneficial especially on SMP systems. The following example starts up to (number of CPUs in a system + 1) jobs, which is the recommended amount:

make -j`expr \`nproc\` + 1`

Flashing U-Boot

Each platform has a slightly different process for updating the content of the flash. The list of supported boards contains links to instructions for updating each supported board.

Generic Gen2 platform

The H2 Stout, M2-W Porter, E2 Silk boards use U-Boot SPL to replace the SPI LOADER since U-Boot v2018.05-rc. This changes the flash layout!

As of U-Boot 2018.05-rc2, the flash layout is as follows:

Flash layout in U-Boot 2018.05-rc2
Offset Size Usage
0x00000 0x40000 U-Boot SPL up to 0x10000 (BootROM size limit), remaining 0x30000 unused (SF erase block is 0x40000 big)
0x40000 0x40000 UNUSED, was SPI LOADER metadata
0x80000 0x40000 UNUSED
0xc0000 0x40000 U-Boot environment
0x100000 0x40000 UNUSED
0x140000 0x80000 U-Boot uImage

1) Build u-boot.img and u-boot-spl.bin as instructed above.

2) Install u-boot.img to SPI NOR at offset 0x140000, for example from already running U-Boot:

  => tftp 0x50000000
  => sf probe
  => sf erase 0x140000 0x80000
  => sf write 0x50000000 0x140000 ${filesize}

3) Install u-boot-spl.bin to SPI NOR at offset 0x0, for example from already running U-Boot:

  => tftp 0x50000000
  => sf probe
  => sf erase 0x0 0x40000
  => sf write 0x50000000 0x0 ${filesize}

After power-cycling the board, U-Boot SPL will come up and load U-Boot from SPI NOR.

Known issues