how to enable -m64 on x86-linux for building ATLAS

Andrew Haley aph@redhat.com
Thu Apr 3 10:27:00 GMT 2008


Dennis Wassel wrote:

> I've been trying to compile the ATLAS library on an 32-bit Linux
> system with my self-compiled gcc 4.3.0, but this fails.
> It boils down to the ATLAS config utility noticing that I have a
> 64-bit processor and trying to compile some low-level stuff with -m64,
> which doesn't work because I have not compiled in 64-bit support. [I
> could force 32-bit mode, but I feel that 64-bit mode surely improves
> performance, which is what ATLAS is for in the first place]
> 
> Ok, so I try and recompile gcc, telling it that I do indeed have a
> 64-bit processor, and it "profiledbootstrap"s itself merrily, until at
> some point ld whines that it cannot find a compatible libc.
> 
> Fine. I'm now going to try to build a 64-bit glibc (and worry where to
> put it later, because I'm not root), and possible the full-fledged
> binutils toolchain and so on, but now I feel this
> chicken-and-egg-problem creeping up to me - wouldn't I need 64-bit
> support in my compiler to create the corresponding glibc?
> 
> D'oh!
> 
> Any pointers, docs or howtos anyone? Much appreciated!

In the 64-bit Linux system we have a backwards compatibility mode that
allows us to run 32-bit applications.  We don't have a corresponding
64-bit mode on 32-bit systems.

Andrew.



More information about the Gcc-help mailing list