ARM: tegra: enable standard clock/reset APIs everywhere

[karo-tx-uboot.git] / doc / README.x86

diff --git a/doc/README.x86 b/doc/README.x86
index 4d50feb720f258685384049401e8f8411c6896cf..ba5bb99dcd1a7edb5ef0bd135d8b1451786c141f 100644 (file)
--- 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:
@@ -1020,24 +1024,54 @@ Features not supported so far (to make it a complete ACPI solution):
  * S3 (Suspend to RAM), S4 (Suspend to Disk).
 
 Features that are optional:
- * ACPI global NVS support. We may need it to simplify ASL code logic if
-   utilizing NVS variables. Most likely we will need this sooner or later.
  * Dynamic AML bytecodes insertion at run-time. We may need this to support
    SSDT table generation and DSDT fix up.
  * SMI support. Since U-Boot is a modern bootloader, we don't want to bring
    those legacy stuff into U-Boot. ACPI spec allows a system that does not
    support SMI (a legacy-free system).
 
-So far ACPI is enabled on BayTrail based boards. Testing was done by booting
+ACPI was initially enabled on BayTrail based boards. Testing was done by booting
 a pre-installed Ubuntu 14.04 from a SATA drive. Installing Ubuntu 14.04 and
 Windows 8.1/10 to a SATA drive and booting from there is also tested. Most
 devices seem to work correctly and the board can respond a reboot/shutdown
 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
 ----------