diff --git a/doc/README.x86 b/doc/README.x86 index 22bfbab..fa49cb8 100644 --- a/doc/README.x86 +++ b/doc/README.x86 @@ -1160,27 +1160,10 @@ to load a 'u-boot-payload.efi', see below test logs on QEMU. 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 ----------