I'm not an SME expert, and I've never run more than 4G in a SME box. I want that out there first-hand...
However, I have seen first-hand how PAE (which is what we're talking about w/ the HUGEMEM kernels) can cause problems with other architectures (*cough* Windows). Keep in mind that PAE is a hack, quite similar to the ol' HIMEM on MS-DOS, where page tables have to be swapped around to access different areas of memory. Also, on *any* 32bit system, most applications will not be able to access more than 3G (or sometimes 4G if compiled for it) no matter how much memory you have.
A couple links worth taking a look at when considering this.
Here's one from some fella named Linus. Not sure who he is but seems to have some opinion on the matter. (*sarcasm*)
http://lkml.org/lkml/2007/11/15/423But quite frankly, I refuse to even care about anything past that. If you
have 12G (or heaven forbid, even more) in your machine, and you can't be
bothered to just upgrade to a 64-bit CPU, then quite frankly, *I*
personally can't be bothered to care.
Here's another from a company named Red Hat. They sound vaguely familiar (*sarcasm*)
http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/release-notes/as-x86/Note
To provide a 4GB address space for both kernel and user space, the kernel must maintain two separate virtual memory address mappings. This introduces overhead when transferring from user to kernel space; for example, in the case of system calls and interrupts. The impact of this overhead on overall performance is highly application dependent.
Just some food for thought before you plunk down for a load of RAM on a SME box. We've used most of the featurea & contribs that you have on your list, and never needed more than 4G for SME to run just fine. For us, until SME comes out w/ a 64bit version, we'll stick with 4G.
Just my $0.02.
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