Re: Binary format output

[Mike Frysinger <vapier at gentoo dot org>]

On Friday 14 July 2006 14:44, Victor Roman Archidona wrote:
> I compiled by hand GCC and binutils (2.17), and when I compile some
> file the output format is "UNIX - System V". I got this with
> `readelf -h program`.
>
> The problem is that I need the default binary output must be "UNIX -
> FreeBSD" and for now I can't fix it without help.

freebsd tweaks the stock bfd elf64 code to change the EI_OSABI to 
ELFOSABI_FREEBSD ... that way the default 'elf-x86-64' target on 
amd64/freebsd systems actually outputs freebsd objects

find attached a patch against cvs head to do this right (i think) ... note 
that ive never done any real bfd/gas hacking before, so this could be pretty 
wrong/incomplete ;)
-mike

Attachment: pgp00000.pgp
Description: PGP signature

--- bfd/config.bfd
+++ bfd/config.bfd
@@ -564,8 +564,8 @@ case "${targ}" in
     want64=true
     ;;
   x86_64-*-freebsd* | x86_64-*-kfreebsd*-gnu)
-    targ_defvec=bfd_elf64_x86_64_vec
-    targ_selvecs="bfd_elf32_i386_vec i386coff_vec bfd_efi_app_ia32_vec"
+    targ_defvec=bfd_elf64_x86_64_freebsd_vec
+    targ_selvecs="bfd_elf32_i386_freebsd_vec i386coff_vec bfd_efi_app_ia32_vec"
     want64=true
     ;;
   x86_64-*-netbsd* | x86_64-*-openbsd*)
--- bfd/configure.in
+++ bfd/configure.in
@@ -709,6 +709,7 @@ do
     bfd_elf64_tradbigmips_vec)	tb="$tb elf64-mips.lo elf64.lo elfxx-mips.lo elf-vxworks.lo elf32.lo $elf ecofflink.lo"; target_size=64 ;;
     bfd_elf64_tradlittlemips_vec) tb="$tb elf64-mips.lo elf64.lo elfxx-mips.lo elf-vxworks.lo elf32.lo $elf ecofflink.lo"; target_size=64 ;;
     bfd_elf64_x86_64_vec)	tb="$tb elf64-x86-64.lo elf64.lo $elf"; target_size=64 ;;
+    bfd_elf64_x86_64_freebsd_vec) tb="$tb elf64-x86-64.lo elf64.lo $elf"; target_size=64 ;;
     bfd_mmo_vec)		tb="$tb mmo.lo" target_size=64 ;;
     bfd_powerpc_pe_vec)         tb="$tb pe-ppc.lo peigen.lo cofflink.lo" ;;
     bfd_powerpc_pei_vec)        tb="$tb pei-ppc.lo peigen.lo cofflink.lo" ;;
--- bfd/elf64-x86-64.c
+++ bfd/elf64-x86-64.c
@@ -3710,3 +3710,33 @@ static const struct bfd_elf_special_sect
   elf64_x86_64_hash_symbol
 
 #include "elf64-target.h"
+
+/* FreeBSD support.  */
+
+#undef	TARGET_LITTLE_SYM
+#define	TARGET_LITTLE_SYM		bfd_elf64_x86_64_freebsd_vec
+#undef	TARGET_LITTLE_NAME
+#define	TARGET_LITTLE_NAME		"elf64-x86-64-freebsd"
+
+/* The kernel recognizes executables as valid only if they carry a
+   "FreeBSD" label in the ELF header.  So we put this label on all
+   executables and (for simplicity) also all other object files.  */
+
+static void
+elf_x86_64_post_process_headers (bfd *abfd,
+			         struct bfd_link_info *info ATTRIBUTE_UNUSED)
+{
+  Elf_Internal_Ehdr *i_ehdrp;
+
+  i_ehdrp = elf_elfheader (abfd);
+
+  /* Put an ABI label supported by FreeBSD >= 4.1.  */
+  i_ehdrp->e_ident[EI_OSABI] = ELFOSABI_FREEBSD;
+}
+
+#undef	elf_backend_post_process_headers
+#define	elf_backend_post_process_headers	elf_x86_64_post_process_headers
+#undef	elf64_bed
+#define	elf64_bed				elf64_x86_64_fbsd_bed
+
+#include "elf64-target.h"
--- bfd/targets.c
+++ bfd/targets.c
@@ -669,6 +669,7 @@ extern const bfd_target bfd_elf64_sparc_
 extern const bfd_target bfd_elf64_tradbigmips_vec;
 extern const bfd_target bfd_elf64_tradlittlemips_vec;
 extern const bfd_target bfd_elf64_x86_64_vec;
+extern const bfd_target bfd_elf64_x86_64_freebsd_vec;
 extern const bfd_target bfd_mmo_vec;
 extern const bfd_target bfd_powerpc_pe_vec;
 extern const bfd_target bfd_powerpc_pei_vec;
@@ -985,6 +986,7 @@ static const bfd_target * const _bfd_tar
 	&bfd_elf64_tradbigmips_vec,
 	&bfd_elf64_tradlittlemips_vec,
 	&bfd_elf64_x86_64_vec,
+	&bfd_elf64_x86_64_freebsd_vec,
 	&bfd_mmo_vec,
 #endif
 	&bfd_powerpc_pe_vec,
--- gas/config/tc-i386.c
+++ gas/config/tc-i386.c
@@ -5822,7 +5822,7 @@ md_parse_option (int c, char *arg)
 
 	list = bfd_target_list ();
 	for (l = list; *l != NULL; l++)
-	  if (strcmp (*l, "elf64-x86-64") == 0)
+	  if (strcmp (*l, ELF64_TARGET_FORMAT) == 0)
 	    {
 	      default_arch = "x86_64";
 	      break;
@@ -5978,7 +5978,7 @@ i386_target_format ()
 	    object_64bit = 1;
 	    use_rela_relocations = 1;
 	  }
-	return flag_code == CODE_64BIT ? "elf64-x86-64" : ELF_TARGET_FORMAT;
+	return flag_code == CODE_64BIT ? ELF64_TARGET_FORMAT : ELF_TARGET_FORMAT;
       }
 #endif
     default:
--- gas/config/tc-i386.h
+++ gas/config/tc-i386.h
@@ -55,6 +55,7 @@ extern unsigned long i386_mach (void);
 
 #ifdef TE_FreeBSD
 #define ELF_TARGET_FORMAT	"elf32-i386-freebsd"
+#define ELF64_TARGET_FORMAT	"elf64-x86-64-freebsd"
 #elif defined (TE_VXWORKS)
 #define ELF_TARGET_FORMAT	"elf32-i386-vxworks"
 #endif
@@ -63,6 +64,10 @@ extern unsigned long i386_mach (void);
 #define ELF_TARGET_FORMAT	"elf32-i386"
 #endif
 
+#ifndef ELF64_TARGET_FORMAT
+#define ELF64_TARGET_FORMAT	"elf64-x86-64"
+#endif
+
 #if ((defined (OBJ_MAYBE_COFF) && defined (OBJ_MAYBE_AOUT)) \
      || defined (OBJ_ELF) || defined (OBJ_MAYBE_ELF))
 extern const char *i386_target_format PARAMS ((void));