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

[Lee Revell <rlrevell@joe-job.com>]

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
arch/x86_64/kernel/entry.S:275: Error: cannot represent relocation type BFD_RELOC_X86_64_32S
arch/x86_64/kernel/entry.S:762: Error: cannot represent relocation type BFD_RELOC_X86_64_32S
arch/x86_64/kernel/entry.S:815: Error: cannot represent relocation type BFD_RELOC_X86_64_32S
arch/x86_64/kernel/entry.S:536: Error: cannot represent relocation type BFD_RELOC_64
arch/x86_64/kernel/entry.S:536: Error: cannot represent relocation type BFD_RELOC_64
arch/x86_64/kernel/entry.S:785: Error: cannot represent relocation type BFD_RELOC_64
arch/x86_64/kernel/entry.S:785: Error: cannot represent relocation type BFD_RELOC_64
make[1]: *** [arch/x86_64/kernel/entry.o] Error 1
make: *** [arch/x86_64/kernel] Error 2

Is this a known toolchain bug?

$ as --version
GNU assembler 2.16.1 Debian GNU/Linux

Lee