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

From: Ken Moffat
Date: Fri Dec 09 2005 - 14:50:12 EST


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.

Ken
--
das eine Mal als Tragödie, das andere Mal als Farce