diff options
Diffstat (limited to 'doc/README.x86')
| -rw-r--r-- | doc/README.x86 | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/doc/README.x86 b/doc/README.x86 index 7d694b1..ba5bb99 100644 --- a/doc/README.x86 +++ b/doc/README.x86 @@ -314,6 +314,10 @@ Offset Description Controlling config Overall ROM image size is controlled by CONFIG_ROM_SIZE. +Note that the debug version of the FSP is bigger in size. If this version +is used, CONFIG_FSP_ADDR needs to be configured to 0xfffb0000 instead of +the default value 0xfffc0000. + --- Intel Galileo instructions for bare mode: @@ -1035,10 +1039,39 @@ command from the OS. For other platform boards, ACPI support status can be checked by examining their board defconfig files to see if CONFIG_GENERATE_ACPI_TABLE is set to y. +EFI Support +----------- +U-Boot supports booting as a 32-bit or 64-bit EFI payload, e.g. with UEFI. +This is enabled with CONFIG_EFI_STUB. U-Boot can also run as an EFI +application, with CONFIG_EFI_APP. The CONFIG_EFI_LOADER option, where U-Booot +provides an EFI environment to the kernel (i.e. replaces UEFI completely but +provides the same EFI run-time services) is not currently supported on x86. + +See README.efi 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. It also supports (with CONFIG_EFI_STUB) booting from +both 32-bit and 64-bit UEFI. 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 +- Support for CONFIG_EFI_LOADER +- Building U-Boot to run in 64-bit mode References ---------- |