2

I tried to compile uefi code using gnu-efi. But I don't understand how to compile my uefi application code.

I get gnu-efi 3.0.2, decompress and type make && make install. I write hello world code:

#include <efi.h>
#include <efilib.h>

EFI_STATUS efi_main (EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable) {
    InitializeLib(ImageHandle, SystemTable);
    Print(L"Hello, world!\n");

    return EFI_SUCCESS;
}

My OS is Ubuntu 15.04.

Jonathon Reinhart
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The coffee 17th cup
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2 Answers2

6

  1. Include the gnu-efi files

    #include <efi.h> 
#include <efilib.h>

    it looks like your includes where removed by SO

  2. create the make file;

If you were building a "Hello, World" program for Linux in a Linux environment, you could compile it without a Makefile. Building the program in Linux for EFI, though, is essentially a cross-compilation operation. As such, it necessitates using unusual compilation and linker options, as well as a post-linking operation to convert the program into a form that the EFI will accept. Although you could type all the relevant commands by hand, a Makefile helps a lot.

ARCH            = $(shell uname -m | sed s,i[3456789]86,ia32,)

OBJS            = main.o
TARGET          = hello.efi

EFIINC          = /usr/include/efi
EFIINCS         = -I$(EFIINC) -I$(EFIINC)/$(ARCH) -I$(EFIINC)/protocol
LIB             = /usr/lib64
EFILIB          = /usr/lib64/gnuefi
EFI_CRT_OBJS    = $(EFILIB)/crt0-efi-$(ARCH).o
EFI_LDS         = $(EFILIB)/elf_$(ARCH)_efi.lds

CFLAGS          = $(EFIINCS) -fno-stack-protector -fpic \
          -fshort-wchar -mno-red-zone -Wall 
ifeq ($(ARCH),x86_64)
  CFLAGS += -DEFI_FUNCTION_WRAPPER
endif

LDFLAGS         = -nostdlib -znocombreloc -T $(EFI_LDS) -shared \
          -Bsymbolic -L $(EFILIB) -L $(LIB) $(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) $^ $@

reference:

http://www.rodsbooks.com/efi-programming/hello.html

Pat
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  • @Thecoffee17thcup can you let me know how can i build that in Ubuntu ? I keep having "fatal error: efi.h: No such file or directory" – Sam Mar 09 '17 at 09:06
  • that's an easy one. your compiler cannot see `efi.h`, check your `make` file; `EFIINC = /usr/include/efi` should point the required gnu-efi header files. – Pat Mar 09 '17 at 11:05
  • What `-fpic` for? – 0andriy Oct 08 '18 at 16:42
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    Position Independent Code read https://wiki.gentoo.org/wiki/Project:AMD64/Fixing_-fPIC_Errors_Guide#What_is_PIC.3F – Pat Oct 09 '18 at 15:43
4

In Ubuntu 18.04, these two lines:

LIB             = /usr/lib64

EFILIB          = /usr/lib64/gnuefi

need to be changed to:

LIB             = /usr/lib

EFILIB          = /usr/lib
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