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Memory Management Unit (MMU)
Freescale Semiconductor
4-9
4.2.8
MMU Read/Write Data Entry Register (MMUDR)
The MMUDR register contains the physical address, page size, cache-mode field, supervisor-protect bit,
read, write, execute permission bits, and lock-entry bit.
MMUBAR
Offset:
0x014 (MMUTR)
Access: User read/write
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
R
VA
ID
SG V
W
Reset 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Figure 4-8. MMU Read/Write TLB Tag Register (MMUTR)
Table 4-8. MMUTR Field Descriptions
Field
Description
31–10
VA
Virtual address. Defines the virtual address mapped by this entry. The number of bits used in TLB hit
determination depends on the page-size field in the corresponding TLB data entry.
9–2
ID
Address space ID (ASID). This extension to the virtual address marks this entry as part of 1 of 256 possible
address spaces. Address space 0x00 can be reserved for supervisor mode. The other 255 address spaces are
used to tag user processes. TLB entry ASID values are compared to the ASID register value for user mode
unless the TLB entry is marked shared (SG = 1). The TLB entry ASID value may be compared to 0x00 for
supervisor accesses or to the ASID. The description of MMUCR[ASM] in
gives details on supervisor
mode and ASID compares.
1
SG
Shared global. Indicates when the entry is shared among user address spaces. If an entry is shared, its ASID
is not part of the TLB hit determination for user accesses.
0 This entry is not shared globally.
1 This entry is shared globally.
Note:
The ASID can determine supervisor mode hits to allow two sharing levels. If SG and MMUCR[ASM] are
set and the ASID is not zero, all users (but not the supervisor) share an entry. If SG and MMUCR[ASM]
are set and the ASID is zero, all users and the supervisor share an entry. The ASM description in
details supervisor mode and ASID compares.
0
V
Valid. Indicates when the entry is valid. Only valid entries generate a TLB hit.
0 Entry is not valid.
1 Entry is valid.
MMUBAR
Offset:
0x018 (MMUTR)
Access: User read/write
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
R
PA
SZ
CM
SP R W X LK
0
W
Reset 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Figure 4-9. MMU Read/Write TLB Data Register (MMUDR)
Содержание MCF54455
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