bug#2790: emacs 22.1.1 cannot open 5GB file on 64GB 64-bit Linux box

[Mike Coleman]

I'm trying to open a large (between 4GB and 5GB) file on a x86-64
Linux box that has 64GB of RAM.  I'm getting the error message
"Maximum buffer size exceeded".  I'm able to create 32GB strings in
Python on this box, so I don't believe it's a ulimit problem or
anything like that.

The contents of /proc/cpuinfo say that the CPU has 48 virtual bits.
I'm guessing that emacs uses maybe six bits or so for overhead, but
that doesn't seem like enough to be causing my problem.

Given the error message, it seems like emacs probably has an internal
idea of a maximum buffer size, but apropos doesn't turn up anything.

I'm sure this has been discussed and I've tried to find these
discussions, but I don't seem to be able to track down the current
thinking on this subject.

Is this a know limitation or a bug?  Can someone who knows provide a
quick summary?

Thanks,
Mike