I should have been more specific. I'm migrating an existing 32-bit OS kernel to be 64-bit, ia32e mode, i.e. x86_64. I have my own libs but the result is a kernel that is a standalone executable. I probably want to build the binutils too, its not that much extra work and I'll know for sure what I've got if I do that. The development machine is an ia32 pc running fc8. The target will be a standalone kernel running in ia32e mode. It sounds like x86_64-pc-linux will probably work for me. What I really want is for the resulting cross tools, gcc, gas, ld, etc. to be 64-bit only. Will that be the case with this build or will I still need to use -m64 in my compile steps? Thanks, FM -----Original Message----- From: gcc-help-owner@xxxxxxxxxxx [mailto:gcc-help-owner@xxxxxxxxxxx] On Behalf Of Brian Dessent Sent: Thursday, February 14, 2008 6:32 PM To: Frank W. Miller Cc: gcc-help@xxxxxxxxxxx Subject: Re: Building a cross compiler for x86_64 "Frank W. Miller" wrote: > I've determined that my gcc build does not support the -w64 compile > option. (I'm running FC8 and its not compiled in by default apparently) I'm assuming you mean -m64 here. > So, I need to build a cross compiler. I have binutils-2.18 and Not necessarily. The gcc i386 backend is bi-arch, meaning that it targets both ia32 and x86_64 from a single backend. So you can simply build a 32 bit gcc that also supports 64 bit. This would not necessarily be a cross compiler, but you of course wouldn't be able to run the resulting binary on the host. To make this work, you first need to install a 64 bit libc however. This means headers, libs, crt*.o, etc. You should be able to do this through your distro. Once you have that you can configure with --enable-targets=all and you should get a 32 bit gcc with -m64. You can still go the cross route but it's more work, you'd need to first create a sysroot containing full 32 and 64 bit libc-devel's, then configure with --target=x86_64-pc-linux --with-sysroot=whatever. Brian
