[U-Boot] bootm, Linux, and device trees

I maintain a U-Boot port for some custom ASICs (Intel Axxia network processors). I've been basing this on v2015.10 for some time. I just rebased to the latest (v2016.07-67-gb8e5997), and though I can get to the U-Boot prompt, Linux no longer boots. As U-Boot seems to require a device tree now, I

[U-Boot] mkimage and load addresses beyond 4 Gb

At present, the load address and entry point are both "unsigned int". I'm porting to aarch64, and will run the SPL at 0x803100. mkimage truncates this to 0x3100. Are there any plans to support a load address and entry point larger than 32 bits? ___