Digi NS9750 User Manual
Page 109
w w w . d i g i e m b e d d e d . c o m
8 5
W o r k i n g w i t h t h e C P U
Fine page tables, which have 1024 entries and split the 1 MB that the table
describes into 1 KB blocks.
Figure 27: First-level descriptor
Table 32 shows first-level descriptor bit assignments.
31
20 19
12 11 10
9
8
0
1
2
3
4
5
0
0
0
0
1
1
1
1
1
1
1
C
B
Domain
Domain
Domain
AP
Coarse page table base address
Section base address
Fine page table base address
Fault
Coarse page table
Section
Fine page table
Bits
Section
Coarse
Fine
Description
[31:20]
[31:10]
[31:12]
Forms the corresponding bits of the physical address.
[19:12]
----
---
SHOULD BE ZERO
[11:10]
---
---
Access permission bits. See "Access permissions and
domains" on page 79 and "Fault Address and Fault Status
registers" on page 96 for information about interpreting the
access permission bits.
9
9
[11:9]
SHOULD BE ZERO
[8:5]
[8:5]
[8:5]
Domain control bits
4
4
4
Must be 1.
[3:2]
---
---
Bits C and B indicate whether the area of memory mapped
by this page is treated as write-back cachable, write-
through cachable, noncached buffered, or noncached
nonbuffered.
---
[3:2]
[3:2]
SHOULD BE ZERO
Table 32: Priority encoding of fault status