Epson ARM720T Manuel D’Utilisation
7: Memory Management Unit
7-12
EPSON
ARM720T CORE CPU MANUAL
7.3.9
Translating large page references
Figure 7-10 shows the complete translation sequence for a 64KB large page.
Figure 7-10 Large page translation from a coarse page table
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 a large page descriptor is included in a fine page table, the high-order six bits of the page
If a 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 index overlap. Each fine page table entry for
a large page must therefore be duplicated 64 times.
31
14 13
0
Translation base
31
14 13
2 1 0
0 0
Table index
Translation base
Modified virtual address
Translation table base
31
20 19
0
Table index
Page index
Level one descriptor
Physical address
31
0
Coarse page table base address
Domain 1
1
2 1
3
4
5
8
9
10
L2
table index
table index
16 15
12 11
31
16 15
0
Page index
Page base address
Level two descriptor
31
0
Coarse page table base address
L2 table index
0
2 1
9
10
31
16 15
0
ap3
Page base address
0
0
ap2 ap1 ap0
1
0
C B
1
2
3
4
5
6
7
8
9
10
11
12