I'd like to mention that many PC cards has got onboard memory which is not
ulitized in most cases (sound cards, video cards etc). These RAM areas
may be used to swap.
> And a subsidary question: given a), is this idea insufficiently ambitious
> and could/should such RAM be usable as real system memory, not just fast
> swap?
As using real system memory can be possibe (imho) with using MMIO (memory
mapped IO), when
the memory of the PCI card is mapped directly to the main CPU address space.
The only problem is about the speed of this memory : I don't know exactly
but speed may casue problem when running code from it by the CPU etc.
But it's much faster than harddisk so swapping gives great performance.
And even if this kind of memory can be used to be accessable for program
running directly it would be slow, so using swap mechanism can be faster
(reading once form that RAM is faster than accessing it at every read
requests by the CPU, PCI DMA access [err, would it be possible therefore ?] can
be stupid as well)
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