
Device Performance Optimization
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
123
Note that configuration of the cache has to be performed in conjunction with configuration of the Memory
Management unit. Refer to section
6.3.6, Memory management unit (MMU)
.
6.3.6
Memory management unit (MMU)
6.3.6.1
Description
The Memory Management Unit is a 32-bit Power Architecture compliant implementation which provides
functionality that includes address translation and application of access attributes to memory ranges
defined in Translation Lookaside Buffer entries. Although the MMU does not directly impact
performance, it is within the MMU that memory regions are configured to permit the use of system cache
to improve performance and Variable Length Encoding (VLE) to enhance code density. Thus it is essential
that the MMU is correctly configured to ensure optimal application performance is achieved.
6.3.6.1.1
Recommended configuration
The core uses MMU Assist Registers (MASx) which are special purpose registers to facilitate reading,
writing and searching the Translation Lookaside Buffer (TLB) entries. These MAS registers are software
managed by
tlbre
,
tlbwe
,
tlbsx
,
tlbsync
, and
tlbivax
instructions. Refer to the core reference manual for
full details of the MMU and its configurations.
There are several MMU Assist Register registers (MAS0–3) that require configuring. Details of these are
provided in the e200z4 Power Architecture® Core Reference Manual. Specifically, the MAS2 register
contains the fields to control whether a specified memory region described by the valid TLB Entry is cache
inhibited or whether VLE encoding is valid.
ICE
Instruction Cache Enable
0: Cache is disabled
1: Cache is enabled
When disabled, cache lookups are not performed for instruction accesses.
Other L1CSR0 cache control operations are still available.
EPN
0
VLE
W
I
M G E
0
1
2
3
4
5
6
7
8
9
10
11
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
SPR - 626; Read/Write
Figure 6-3. MMU Assist Register 2 (MAS2)
Table 6-3. MAS2 field descriptions
Field
Description
EPN
Effective page number [0:21]
Table 6-2. L1CSR1 field descriptions (continued)
Field
Description
Содержание MPC5644A
Страница 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Страница 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Страница 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Страница 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Страница 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Страница 130: ...Device Performance Optimization MPC5644A Microcontroller Reference Manual Rev 6 130 Freescale Semiconductor...
Страница 204: ...Multi Layer AHB Crossbar Switch XBAR MPC5644A Microcontroller Reference Manual Rev 6 204 Freescale Semiconductor...
Страница 212: ...Peripheral Bridge PBRIDGE MPC5644A Microcontroller Reference Manual Rev 6 212 Freescale Semiconductor...
Страница 558: ...System Integration Unit SIU MPC5644A Microcontroller Reference Manual Rev 6 558 Freescale Semiconductor...
Страница 582: ...Frequency modulated phase locked loop FMPLL MPC5644A Microcontroller Reference Manual Rev 6 582 Freescale Semiconductor...
Страница 766: ...Enhanced Time Processing Unit eTPU2 MPC5644A Microcontroller Reference Manual Rev 6 766 Freescale Semiconductor...
Страница 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Страница 1236: ...System Information Module and Trim SIM MPC5644A Microcontroller Reference Manual Rev 6 1236 Freescale Semiconductor...
Страница 1250: ...Cyclic Redundancy Checker CRC Unit MPC5644A Microcontroller Reference Manual Rev 6 1250 Freescale Semiconductor...
Страница 1336: ...Deserial Serial Peripheral Interface DSPI MPC5644A Microcontroller Reference Manual Rev 6 1336 Freescale Semiconductor...
Страница 1388: ...Enhanced Serial Communication Interface ESCI MPC5644A Microcontroller Reference Manual Rev 6 1388 Freescale Semiconductor...
Страница 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...
Страница 1624: ...FlexRay Communication Controller FlexRay MPC5644A Microcontroller Reference Manual Rev 6 1624 Freescale Semiconductor...
Страница 1670: ...JTAG Controller JTAGC MPC5644A Microcontroller Reference Manual Rev 6 1670 Freescale Semiconductor...
Страница 1692: ...Nexus Port Controller NPC MPC5644A Microcontroller Reference Manual Rev 6 1692 Freescale Semiconductor...
Страница 1701: ...Development Trigger Semaphore DTS MPC5644A Microcontroller Reference Manual Rev 6 Freescale Semiconductor 1701...
Страница 1702: ...Development Trigger Semaphore DTS MPC5644A Microcontroller Reference Manual Rev 6 1702 Freescale Semiconductor...