Re: i386 -> x86_64 cross compile failure (binutils bug?)

Lee Revell
2005-12-09T19:57:36Z

On Fri, 2005-12-09 at 19:50 +0000, Ken Moffat wrote:
> On Fri, 9 Dec 2005, Lee Revell wrote:
>
> > I'm trying to build an x66-64 kernel on a 32 bit system (Ubuntu 5.10).
> > I added -m64 to the CFLAGS as per the gcc docs. But the build fails
> > with:
> >
> > $ make ARCH=x86_64
> > [...]
> > CC init/initramfs.o
> > CC init/calibrate.o
> > LD init/built-in.o
> > CHK usr/initramfs_list
> > CC arch/x86_64/kernel/process.o
> > CC arch/x86_64/kernel/signal.o
> > AS arch/x86_64/kernel/entry.o
> > arch/x86_64/kernel/entry.S: Assembler messages:
> > arch/x86_64/kernel/entry.S:204: Error: cannot represent relocation type BFD_RELOC_X86_64_32S
>
> Unless ubuntu provides a biarch toolchain (and the fact gcc accepts
> '-m64' means nothing - use 'file' on init/built-in.o), you have to build
> a cross toolchain, (just binutils and gcc), put that on your path, and
> use
>
> make ARCH=x86_64 CROSS_COMPILE=x86_64-pc-linux-gnu-
>
> so that the build will use x86_64-pc-linux-gnu-as and friends. You
> should not need to mess with the CFLAGS.
>

$ file init/built-in.o
init/built-in.o: ELF 64-bit LSB relocatable, AMD x86-64, version 1
(SYSV), not stripped

>From man gcc, i386 section:

-m32
-m64
Generate code for a 32-bit or 64-bit environment. The 32-bit
environment sets int, long and pointer to 32
bits and generates code that runs on any i386 system. The
64-bit environment sets int to 32 bits and long
and pointer to 64 bits and generates code for AMD's x86-64
architecture.

Lee