@@ -5,6 +5,52 @@ config SYS_ARCH
default "x86"
choice
+ prompt "Run U-Boot in 32/64-bit mode"
+ default X86_RUN_32BIT
+ help
+ U-Boot can be built as a 32-bit binary which runs in 32-bit mode
+ even on 64-bit machines. In this case SPL is not used, and U-Boot
+ runs directly from the reset vector (via 16-bit start-up).
+
+ Alternatively it can be run as a 64-bit binary, thus requiring a
+ 64-bit machine. In this case SPL runs in 32-bit mode (via 16-bit
+ start-up) then jumps to U-Boot in 64-bit mode.
+
+ For now, 32-bit mode is recommended, as 64-bit is still
+ experimental and is missing a lot of features.
+
+config X86_RUN_32BIT
+ bool "32-bit"
+ help
+ Build U-Boot as a 32-bit binary with no SPL. This is the currently
+ supported normal setup. U-Boot will stay in 32-bit mode even on
+ 64-bit machines. When booting a 64-bit kernel, U-Boot will switch
+ to 64-bit just before starting the kernel. Only the bottom 4GB of
+ memory can be accessed through normal means, although
+ arch_phys_memset() can be used for basic access to other memory.
+
+config X86_RUN_64BIT
+ bool "64-bit"
+ select X86_64
+ select SUPPORT_SPL
+ select SPL
+ select SPL_SEPARATE_BSS
+ help
+ Build U-Boot as a 64-bit binary with a 32-bit SPL. This is
+ experimental and many features are missing. U-Boot SPL starts up,
+ runs through the 16-bit and 32-bit init, then switches to 64-bit
+ mode and jumps to U-Boot proper.
+
+endchoice
+
+config X86_64
+ bool
+
+config SPL_X86_64
+ bool
+ depends on SPL
+
+choice
prompt "Mainboard vendor"
default VENDOR_EMULATION
Add a new CONFIG_X86_64 option which will eventually cause U-Boot to be built as a 64-bit application, with SPL doing the 16/32-bit init. Signed-off-by: Simon Glass <sjg@chromium.org> --- arch/x86/Kconfig | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+)