Where to get u-boot?
git://git.denx.de/u-boot.git
Which platform to use in u-boot?
vexpress_ca9x4
Build uboot:
>make CROSS_COMPILE="your cross compile tool chain path" vexpress_ca9x4_defconfig
>make CROSS_COMPILE="your cross compile tool chain path"
your cross compile tool chain path may like: /opt/gcc-linaro-5.3-2016.02-x86_64_arm-linux-gnueabi/bin/arm-linux-gnueabi-
Run uboot in QEMU:
>qemu-system-arm -M vexpress-a9 -nographic -m 512 -kernel u-boot
You should see the u-boot get run.