See README.u-boot_on_efi and README.uefi for details of EFI support in U-Boot.
-64-bit Support
---------------
-U-Boot supports booting a 64-bit kernel directly and is able to change to
-64-bit mode to do so. However, U-Boot itself is currently always built
-in 32-bit mode. Some access to the full memory range is provided with
-arch_phys_memset().
-
-The development work to make U-Boot itself run in 64-bit mode has not yet
-been attempted. The best approach would likely be to build a 32-bit SPL
-image for U-Boot, with CONFIG_SPL_BUILD. This could then handle the early CPU
-init in 16-bit and 32-bit mode, running the FSP and any other binaries that
-are needed. Then it could change to 64-bit model and jump to U-Boot proper.
-
-Given U-Boot's extensive 64-bit support this has not been a high priority,
-but it would be a nice addition.
-
TODO List
---------
- Audio
- Chrome OS verified boot
-- Building U-Boot to run in 64-bit mode
References
----------