Digi NS9215 manual Translation sequence for large page references

Translation sequence for large page references

WO R K I N G W I T H T H E C P U

MemoryManagement Unit (MMU)

	Modified virtual address
31	2019	1615	12 11		0
Table index				Page	index
	table index

Translation table base
31		14 13						0
Translation base
31		14 13				2	1 0
Translation base		Table index					0	0
First-level descriptor
31		10 9	8	5 4	3	2	1 0
Coarse page table base address			Domain 1				0	1
31		10 9				2	1	0
Coarse page table base address			L2 table index				0	0
Second-level descriptor
31	1615	121110 9	8 7 6	5 4	3 2		1	0
Page base address		AP3 AP2 AP1 AP0 C B 0 1
Physical address
31	1615							0

Page base address

Page index

Because the upper four bits of the page index and low-order four bits of the coarse page table index overlap, each coarse page table entry for a large page must be duplicated 16 times (in consecutive memory locations) in the coarse page table.

If the large page descriptor is included in a fine page table, the high-order six bits of the page index and low-order six bits of the fine page table overlap. Each fine page table entry for a large page must be duplicated 64 times.

116Hardware Reference NS9215