efi: Add support for loading U-Boot through an EFI stub
It is useful to be able to load U-Boot onto a board even if is it already
running EFI. This can allow access to the U-Boot command interface, flexible
booting options and easier development.
The easiest way to do this is to build U-Boot as a binary blob and have an
EFI stub copy it into RAM. Add support for this feature, targeting 32-bit
initially.
Also add a way to detect when U-Boot has been loaded via a stub. This goes
in common.h since it needs to be widely available so that we avoid redoing
initialisation that should be skipped.
Signed-off-by: Simon Glass <sjg@chromium.org>
Improvements to how the payload is built:
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/Makefile b/Makefile
index 620c18f..752ee0d 100644
--- a/Makefile
+++ b/Makefile
@@ -755,6 +755,7 @@
endif
ALL-$(CONFIG_REMAKE_ELF) += u-boot.elf
ALL-$(CONFIG_EFI_APP) += u-boot-app.efi
+ALL-$(CONFIG_EFI_STUB) += u-boot-payload.efi
ifneq ($(BUILD_ROM),)
ALL-$(CONFIG_X86_RESET_VECTOR) += u-boot.rom
@@ -790,6 +791,9 @@
quiet_cmd_zobjcopy = OBJCOPY $@
cmd_zobjcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
+quiet_cmd_efipayload = OBJCOPY $@
+cmd_efipayload = $(OBJCOPY) -I binary -O $(EFIPAYLOAD_BFDTARGET) -B $(EFIPAYLOAD_BFDARCH) $< $@
+
quiet_cmd_mkimage = MKIMAGE $@
cmd_mkimage = $(objtree)/tools/mkimage $(MKIMAGEFLAGS_$(@F)) -d $< $@ \
$(if $(KBUILD_VERBOSE:1=), >/dev/null)
@@ -1087,6 +1091,26 @@
u-boot-app.efi: u-boot FORCE
$(call if_changed,zobjcopy)
+u-boot-dtb.bin.o: u-boot-dtb.bin FORCE
+ $(call if_changed,efipayload)
+
+u-boot-payload.lds: $(LDSCRIPT_EFI) FORCE
+ $(call if_changed_dep,cpp_lds)
+
+# Rule to link the EFI payload which contains a stub and a U-Boot binary
+quiet_cmd_u-boot_payload ?= LD $@
+ cmd_u-boot_payload ?= $(LD) $(LDFLAGS_EFI_PAYLOAD) -o $@ \
+ -T u-boot-payload.lds \
+ lib/efi/efi.o lib/efi/efi_stub.o u-boot-dtb.bin.o \
+ $(addprefix arch/$(ARCH)/lib/efi/,$(EFISTUB))
+
+u-boot-payload: u-boot-dtb.bin.o u-boot-payload.lds FORCE
+ $(call if_changed,u-boot_payload)
+
+OBJCOPYFLAGS_u-boot-payload.efi := $(OBJCOPYFLAGS_EFI)
+u-boot-payload.efi: u-boot-payload FORCE
+ $(call if_changed,zobjcopy)
+
u-boot-img.bin: spl/u-boot-spl.bin u-boot.img FORCE
$(call if_changed,cat)