Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet
Product codes
AT91SAM9N12-EK
Memory Management Unit
3-12
Copyright © 2001-2003 ARM Limited. All rights reserved.
ARM DDI0198D
Coarse page table descriptor bit assignments are described in Table 3-5.
3.2.6
Fine page table descriptor
A fine page table descriptor provides the base address of a page table that contains
second-level descriptors for large page, small page, or tiny page accesses. Fine page
tables have 1024 entries, splitting the 1MB that the table describes into 1KB blocks.
Figure 3-7 shows the format of a fine page table descriptor.
second-level descriptors for large page, small page, or tiny page accesses. Fine page
tables have 1024 entries, splitting the 1MB that the table describes into 1KB blocks.
Figure 3-7 shows the format of a fine page table descriptor.
Figure 3-7 Fine page table descriptor
Note
If a fine page table descriptor is returned from the first-level fetch, a second-level fetch
is initiated.
is initiated.
Table 3-5 Coarse page table descriptor bits
Bits
Description
[31:10]
These bits form the base for referencing the second-level descriptor (the coarse
page table index for the entry is derived from the MVA)
page table index for the entry is derived from the MVA)
[9]
Always written as 0
[8:5]
These bits specify one of the 16 possible domains (held in the domain access
control registers) that contain the primary access controls
control registers) that contain the primary access controls
[4]
Always written as 1
[3:2]
Always written as 0
[1:0]
These bits must be 01 to indicate a coarse page table descriptor
1
Fine page table base address
31
12 11
9 8
5 4 3 2 1 0
SBZ
Domain
1 SBZ 1