Sparse Memory?

[ksp7498]

I've noticed that my main computer (an abit IL8 + pentium 4 560j + 1gb of ram) has the option for Sparse Memory, an option which typically doesn't seem to be available on normal desktop computers (at least not on any of the other computers I routinely use). However, I'm unclear as to what practical difference it really makes over flat memory. I understand that sparse memory allows for there to be address gaps in the memory space, such as would be present in a system with hot swappable ram. However, besides this does sparse memory provide any real advantages or disadvantages?

I compiled my kernel with sparse instead of flat memory just to see what happened and there was no noticeable difference in anything. Does this setting have any real purpose for a system that doesn't have hot swappable ram?
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[Ezhdeha]

Sparse memory is not just for systems with hot-swappable RAM but also for systems with NUMA architecture as well as systems with over 4GB of RAM that need to take account of a memory hole for addressing.

If you have a 32bit system without hotswappable RAM you will not need sparse memory.
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