Re: perspectives on 32 bit vs 64 bit

[Adam Skutt <askutt@wnec.edu>]

Lennart Sorensen wrote:
> No 64GB max is the limit on inte's memory extensions on i386.  If linux
> limits it to less than that, I am not aware of it.  Of course I have
> never had a machine with that much memory either.
AFAIK, 16 GiB is still the practical limit due to the way/where the
page_mem array must be stored.  This was certainly the case in 2.4.

The only easy way around it is to remove the memory split entirely
(i.e., both userspace and kernelspace have 4G all the time), but this
carries a terrible performance hit as the entire TLB cache would be
flushed on context switch.

RH carried the patch in some of their enterprise kernels, at least in
the past.  I don't know if they still do for 2.6.

FWIW,
Adam