Hi jjac705,
In the building bootloader document, you will need to start with download and setup the toolchain first. example as below:
Depends on your requirement, you can build U-boot first without the Linux kernel to have the system boot up.
Download and setup the toolchain required for Cyclone V SoC and Arria 10 SoC:
wget https://developer.arm.com/-/media/Files/downloads/gnu/11.2-2022.02/binrel/gcc-arm-11.2-2022.02-x86_64-arm-none-linux-gnueabihf.tar.xz
tar xf gcc-arm-11.2-2022.02-x86_64-arm-none-linux-gnueabihf.tar.xz
rm gcc-arm-11.2-2022.02-x86_64-arm-none-linux-gnueabihf.tar.xz
export PATH=`pwd`/gcc-arm-11.2-2022.02-x86_64-arm-none-linux-gnueabihf/bin:$PATH
Thanks.
Regards,
Aik Eu