1. Production of tool chain

1.1 Tools

　　Software tool: crosstool-ng

　　Download address: git clone https://github.com/crosstool-ng/crosstool-ng

　　The crosstool-ng environment requires libncurse5-dev 

　　sudo apt-get install libncurse5-dev

　　Install autoconf: sudo apt-get install autoconf

　　Enter the crosstool-ng directory, execute ./bootstrap, and generate the configure execution file

　　Check the installation environment. If any errors are reported, install the software: ./configure --prefix=`pwd`/crosstool　

　　The required software is:

　　sudo apt-get install gperf bison flex texinfo help2man gawk

　　Execute the command make to execute the command:

　　make install

　　export PATH="${PATH}:`pwd`/crosstool/bin"

1.2 Start production

1.2.1 Create target folder

　　Create three folders in the root directory:

　　mkdir src x-tools crosstool

1.2.2 Environment

　　Enter the crosstool directory: cd ~/.crosstool

　　Execution: ct-ng list-samples

　　Select arm-unknown-linux-gnueabi as the template for the cross-compilation tool chain

　　Execute the command: ct-ng show-arm-unknown-linux-gnueabi to view the configuration required to compile the cross-compilation tool chain

　　Download gcc 6.3.0: wget http://ftp.gnu.org/gnu/gcc/gcc-6.3.0/gcc-6.3.0.tar.gz

　　Execute command: ct-ng arm-unknown-linux-gnueabi

　　Execute command: ct-ng menuconfig

　　Select Target options

　　           *** Target optimisations ***
           (armv4t) Architecture level: instruction set architecture, exynos4412 is armv7-a architecture, -march=name
           (arm920t) Emit assembly for CPU: CPU core type, -mcpu=name
           () Tune for CPU : Optimization of CPU, please check the chip manual for details, -mtune=name

　　The latest version of crosstool-ng only needs to select the first and second projects.

　　Select toolchain options:

　　u-boot 2016.01 does not support GCC6, so the GCC version needs to be changed to between GCC5.0 and GCC6.0.

　　Save and exit.

1.2.3 Compilation

　　Execute command: ct-ng build

　　Compiled successfully:

　　Create environment variables:

　　vim .bashrc, add the following line

　　PATH=~/x-tools/arm-s3c2440a-linux-gnueabihf/bin:$PATH/

　　Execute source .bashrc

 　　Execute arm-s3c2440a-linux-gnueabi-gcc -v

　　u-boot 2016.01 does not support GCC6, so the GCC version needs to be changed to between GCC5.0 and GCC6.0.

2. Establish u-boot working directory

　　Download u-boot_2016.01 version and unzip u-boot.

2.1 Board directory modification

2.1.1 Create jz2440 board

　　View the files in the ../board/samsung/ directory:

　　In this version, 2440 has been deprecated. Therefore, smdk2410 is selected as the template to create 2440 u-boot.

2.1.2 jz2440 file name modification

　　Modify file name:

2.1.3 Kconfig modification

　　Modify the Kconfig and Makefile files and change smdk2410 inside to jz2440, as follows:

　　Kconfig file:

2.1.4 Makefile modification

2.2 Modify header file

　　Add content to the header file:

　　Add support for S3C2440

　　Find the file containing the header file smdk2410.h:

　　Nothing needs to be modified

2.3 Modify configuration file　

　　The current new version of u-boot is the same as the Linux source code. Make menuconfig is executed for configuration, so there must be jz2440 configuration in the configs directory.

　　Configuration in the config directory:

2.5 Modify the configuration file under arch/arm

　　arch/arm/Kconfig, which adds support for jz2440

2.6 Modify rch/arm/include/asm/mach-types.h

3. Configure .config and compile u-boot

3.1 configuration.config

　　Execute command: make jz2440_defconfig

　　Execute command: make menuconfig

　　Select the target_select item in ARM architecture, and then select jz2440:

　　Configure the command line prompt of u-boot:

　　Save and exit configuration.

3.2 Compilation

　　Compiled successfully:

4. Compilation errors

4.1 Not enough room for program headers

　　arm-2440-linux-gnueabi-ld.bfd: u-boot: Not enough room for program headers, try linking with -N
　　arm-2440-linux-gnueabi-ld.bfd: final link failed: Bad value
　　make: *** [Makefile:1193: u-boot] Error 1

 　　Solution: https://www.mail-archive.com/u-boot@lists.denx.de/msg235861.html

　　Add the following lines to the Makefile in the root directory: