Wink Saville’s Blog

Learned something new from TJ over at Codegen today, he solved a problem where we needed to have 32bit code linked with 64bit code but the linker wouldn’t do it. Apparently this use to work without doing anything, but with the latest linker (ld) code it doesn’t. TJ figured out all that needed to be done was use objcopy to convert the 32bit format to 64bit format:

objcopy -O elf64-x86_64 32bit.o 64bit.o

One other noteworthy element to determine the output formats that objcopy supports use objcopy –info or objcopy –help

wink@ic2d1:$ objcopy --info
BFD header file version (GNU Binutils for Ubuntu) 2.18

elf64-x86-64
 (header little endian, data little endian)
  i386
elf32-i386
 (header little endian, data little endian)
  i386
a.out-i386-linux
 (header little endian, data little endian)
  i386
efi-app-ia32
 (header little endian, data little endian)
  i386
efi-app-x86_64
 (header little endian, data little endian)
  i386
elf64-little
 (header little endian, data little endian)
  i386
elf64-big
 (header big endian, data big endian)
  i386
elf32-little
 (header little endian, data little endian)
  i386
elf32-big
 (header big endian, data big endian)
  i386
srec
 (header endianness unknown, data endianness unknown)
  i386
symbolsrec
 (header endianness unknown, data endianness unknown)
  i386
tekhex
 (header endianness unknown, data endianness unknown)
  i386
binary
 (header endianness unknown, data endianness unknown)
  i386
ihex
 (header endianness unknown, data endianness unknown)
  i386

               elf64-x86-64 elf32-i386 a.out-i386-linux efi-app-ia32
          i386 elf64-x86-64 elf32-i386 a.out-i386-linux efi-app-ia32

               efi-app-x86_64 elf64-little elf64-big elf32-little elf32-big
          i386 efi-app-x86_64 elf64-little elf64-big elf32-little elf32-big

               srec symbolsrec tekhex binary ihex
          i386 srec symbolsrec tekhex binary ihex