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##################################################################################
## ##
## BUILDING HELLOWORLD.EFI WIH GNU-EFI ##
## ##
##################################################################################
#################################################################################
# SUMMARY #
#################################################################################
Minimal working example:
hello.c
---------------------------------------------------------------------------------
#include <efi.h>
#include <efilib.h>
EFI_STATUS
EFIAPI
efi_main (EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable) {
InitializeLib(ImageHandle, SystemTable);
Print(L"Hello, world!\n");
return EFI_SUCCESS;
}
Makefile
--------------------------------------------------------------------------------
ARCH = $(shell uname -m | sed s,i[3456789]86,ia32,)
OBJS = hello.o
TARGET = hello.efi
EFIINC = /usr/include/efi
EFFINCS = -I$(EFIINC) -I$(EFIINC)/$(ARCH) -I$(EFIINC)/protocol
EFILIB = /usr/lib
EFI_CRT_OBJS = $(EFILIB)/crt0-efi-$(ARCH).o
EFI_LDS = $(EFILIB)/elf_$(ARCH)_efi.lds
CFLAGS = $(EFFINCS) -fno-stack-protector -fpic \
-fshort-wchar -mno-red-zone -Wall
ifeq ($(ARCH),x86_64)
CFLAGS += -DEFI_FUNCTION_WRAPPER
endif
LDFLAGS = -nostdlib -znocombreloc -T $(EFI_LDS) -shared \
-Bsymbolic -L $(EFILIB) $(EFI_CRT_OBJS)
all: $(TARGET)
hello.so: $(OBJS)
ld $(LDFLAGS) $(OBJS) -o $@ -lefi -lgnuefi
%.efi: %.so
objcopy -j .text -j .sdata -j .data -j .dynamic \
-j .dynsym -j .rel -j .rela -j .reloc \
--target=efi-app-$(ARCH) $^ $@
#################################################################################
# https://wiki.osdev.org/GNU-EFI #
#################################################################################
GNU-EFI is a very lightweight developing environment to create UEFI applications.
It is a set of libraries and headers for compiling UEFI applications with a
system's native GCC.
You can use host native compiler, then convert resulting ELF into UEFI-compatible
PE.
OR
Use GCC Cross-Compiler generating PE directly.
*********************************************************************************
* $ git clone https://git.code.sf.net/p/gnu-efi/code gnu-efi *
* $ cd gnu-efi *
* $ make *
*********************************************************************************
This should create
* crt0-efi-x86_64.o:
A CRT0 (C runtime initialization code) that will call the
"efi_main" function
* libgnuefi.a:
A library containing a single function (_relocate)
that is used by the CRT0
* (optional) libefi.a:
A library containing convenience functions like CRC computation, string
length calculation, and easy text printing
HEADERS can be used from:
* /usr/include/efi (updated to the latest)
* from EDK2 package
* Or from gnu-efi/inc
LINKER SCRIPT:
* gnu-efi/gnuefi/elf_x86_64_efi.lds
OR
* /usr/lib/elf_x86_64_efi.lds
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