Bug#295678: kernel-image packages with CONFIG_HIGHMEM64G=y enabled

[dann frazier <dannf@dannf.org>]

On Tue, 2005-08-09 at 11:29 +0200, Christian Hammers wrote:
> Hello
> 
> The problems is not Dell PowerEdge specific. My TYAN Tiger-i7320-S5350
> (standard dual xeon server from www.ipc2u.com) also reports only 3.5GB 
> after booting the Sarge 2.6 kernel :-( The BIOS reports full 4GB.
> So if it does not hurt anybody I suggest turning on 64GB support.

>From arch/i386/Kconfig:

    If more than 4 Gigabytes is used then answer "64GB" here. This
    selection turns Intel PAE (Physical Address Extension) mode on.
    PAE implements 3-level paging on IA32 processors. PAE is fully
    supported by Linux, PAE mode is implemented on all recent Intel
    processors (Pentium Pro and better). NOTE: If you say "64GB" here,
    then the kernel will not boot on CPUs that don't support PAE!

So it looks like this would hurt other users.  And, on machines that do
support PAE, I've seen benchmarks that demonstrate a significant
performance loss.  However, this was on a 2.4.25 kernel, not a recent
2.6, and I no longer have a link to those results - google might.

I think supporting these machines would mean adding an additional x86
kernel-image flavor.