x86: Add a way to call 32-bit code from 64-bit mode
The procedure to drop from 64-bit mode to 32-bit is a bit messy. Add a
function to take care of it. It requires identity-mapped pages and that
the calling code is running below 4GB.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/cpu/Makefile b/arch/x86/cpu/Makefile
index 5e058c0..e797925 100644
--- a/arch/x86/cpu/Makefile
+++ b/arch/x86/cpu/Makefile
@@ -12,6 +12,12 @@
obj-$(CONFIG_X86_RESET_VECTOR) += resetvec.o start16.o
obj-y += interrupts.o cpu.o cpu_x86.o call64.o
+AFLAGS_REMOVE_call32.o := -mregparm=3 \
+ $(if $(CONFIG_EFI_STUB_64BIT),-march=i386 -m32)
+AFLAGS_call32.o := -fpic -fshort-wchar
+
+extra-y += call32.o
+
obj-$(CONFIG_INTEL_BAYTRAIL) += baytrail/
obj-$(CONFIG_SYS_COREBOOT) += coreboot/
obj-$(CONFIG_EFI_APP) += efi/