You get to PGF-R with VMA the address you want, but
the hardware signaled a page fault.

	((md) vma)
	(dispatch l2-map-status-code d-pgf)

This can either:

	call PGF-MAP-MISS
	jump to PGF-RDONLY
	call PGF-RWF
	jump to PGF-PDL
	jump to PGF-MAR
	ILLOP

The interesting case is PGF-MAP-MISS

make sure L1 map is loaded for this address
if address was in real memory, jump to PGF-L2A,
	otherwise, it was for a piece of hardware so do that

	(call search-page-hash-table)
	(dispatch pht1-swap-status-code md d-pgf-pht)

D-PGF-PTH: (these are all jumps)
	(SWAPIN)		;0 PHT ENTRY INVALID, GET PAGE FROM DISK
	(PGF-RL)		;1 NORMAL, RELOAD PAGE MAP
	(PGF-FL)		;2 FLUSHABLE, CHANGE BACK TO NORMAL
	(PGF-PRE)		;3 PREPAGED, CHANGE TO NORMAL, WE WANT IT NOW
	(PGF-AG)		;4 AGE, CHANGE BACK TO NORMAL
	(PGF-RL)		;5 WIRED DOWN, RELOAD PAGE MAP
	(P-BIT ILLOP)		;6 NOT USED
	(P-BIT ILLOP)		;7 NOT USED

SWAPIN:
	((A-DISK-SWAPIN-VIRTUAL-ADDRESS) DPB M-ZERO Q-ALL-BUT-POINTER A-PGF-VMA)
	((A-DISK-SWAP-IN-CCW-POINTER) (A-CONSTANT DISK-SWAP-IN-CCW-BASE))
	((A-DISK-SWAPIN-SIZE) (A-CONSTANT 1))

if multi-page-swapin is disabled, jump to SWAPIN-SIZE-X

otherwise, go into a loop incrementing A-DISK-SWAPIN-SIZE until:
	we have gone around the loop the number of times specified in
		the region-swapin-quantum
	we get to a page that belongs to another region
	we get to a page that is already swapped in
	we are the scavenger, and the page under consideration
		does not have any volatile pointers

jump to swapin0-a

	(call swapin0)

SWAPIN0:
	M-B <- a-findcore-scan-pointer + 1
FINDCORE0:
loop using M-B to scan physical-page-data looking for a flushable page

a page is acceptable if:

	its physical-page-data entry is not all ones
	its swap status in PHT1 is either pre-page or flushable

If there aren't any, then run the AGER one full cycle, and look again.

This page has to be written if:
	The PHT1 modified bit is on
	It is currently READ/WRITE
	It is a PDL page
	It is a MAR page

The other choice is to be either READ-ONLY or RWF

Assuming the page has to be written out:
	((A-DISK-SWAP-OUT-CCW-POINTER) (A-CONSTANT DISK-SWAP-OUT-CCW-BASE))
	((A-DISK-PAGE-WRITE-COUNT) M+A+1 M-ZERO A-DISK-PAGE-WRITE-COUNT)
	and put this page on the CCW list
Then see if multiple page swapouts are enabled