I got a problem in linking when I moved my osdev to linux where it worked previously on gcc 3.5.* and binutils 2.18 (compiled to output x86_64-elf) running under cygwin.
Here are the infos:
gcc -v
Using built-in specs.
Target: i686-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.4.4-14ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.4 --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-targets=all --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=i686-linux-gnu --host=i686-linux-gnu --target=i686-linux-gnu
Thread model: posix
gcc version 4.4.5 (Ubuntu/Linaro 4.4.4-14ubuntu5)
ld -v
GNU ld (GNU Binutils for Ubuntu) 2.20.51-system.20100908
part of ld -help
....
ld: supported targets: elf32-i386 a.out-i386-linux pei-i386 elf32-little elf32-big elf64-x86-64 pei-x86-64 elf64-l1om elf64-little elf64-big plugin srec symbolsrec verilog tekhex binary ihex trad-core
....
void main(){
/**some code here**/
}
[bits 64]
global start
extern main
start:
call main
OUTPUT_FORMAT(elf64-x86-64);
offset = 0x1000000;
ENTRY(start);
SECTIONS{
. = offset;
.text : AT(ADDR(.text) - offset){
_code = .;
*(.text)
(.rodata)
. = ALIGN(4096);}
.data : AT(ADDR(.data) - offset){
_data = .;
*(.data)
. = ALIGN(4096);}
.bss : AT(ADDR(.bss) - offset){
_bss = .;
*(.bss)
*(COMMON)
. = ALIGN(4096);}
_end = .;
/DISCARD/ :
{*(.comment)}
}
nasm -f elf64 -o start.o start.asm
echo .
echo .
echo .
gcc -m64 -ffreestanding -nostdlib -mno-red-zone -mno-mmx -mno-sse -mno-sse2 -mno-sse3 -mno-3dnow -c -o main.o main.c
echo .
echo .
echo .
ld -nostdlib -nodefaultlibs -T link.ld -o out.elf start.o main.o
.
.
.
.
.
.
ld: i386:x86-64 architecture of input file 'start.o' is incompatible with i386 output
ld: i386:x86-64 architecture of input file 'main.o' is incompatible with i386 output
Try this:
LDEMULATION="elf_x86_64"
ld -nostdlib -nodefaultlibs -T link.ld -o out.elf start.o main.o