SAGE_FAT_BINARIES and SAGE_ATLAS_ARCH - compile for old processors

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Hi, I recently compiled a new version of the Sage Live CD. In older versions it was enough to set SAGE_FAT_BINARIES='yes' to create a binary with low requirements on processor instructions (like "sse2" instruction set).

In the newer versions I also used SAGE_ATLAS_ARCH='base' flag, but now I have a report that it is not working properly on an old pentium processor.

I read something in the sage-devel group that there might be some interference between those build flags. What is the present procedure to produce a true "fat" binary which should run on possibly the widest range of hardware (without having to grant to use modern hardware to full extend).

thanks