From: Andi Kleen <ak@muc.de>

Some x86-64 users were complaining that coredumps >2GB don't work.

This will enable large coredump for everybody.  Apparently the 32bit
gdb/binutils cannot handle them, but I hear the binutils people are working
on fixing that.  I doubt it will harm people - unreadable coredumps are not
worse than no coredump and it won't make any difference in space usage if
you get a 1.99GB or a 2.5GB coredump.  So just enable it unconditionally.
If it should be really a problem for 32bit the rlimit defaults in
resource.h could be changed.

For file systems that don't support O_LARGEFILE you should just get an
truncated coredumps for big address spaces.