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Memory Management Unit (MMU)
4-20
Freescale Semiconductor
Figure 4-11. Processor Local Bus Address and Attributes Generation
4.3.8
MMU Implementation
The MMU implements a 64-entry full-associative Harvard TLB architecture with 32-entry ITLB and
DTLB. This section details the operation and looks at the size, frequency, miss rate, and miss recovery time
of this TLB implementation.
4.3.8.1
TLB Address Fields
Because the TLB has a total of 64 entries (32 each for the instruction and data TLBs), a 6-bit address field
is necessary. TLB addresses 0–31 reference the ITLB; TLB addresses 32–63 reference the DTLB.
In the MMUOR register, bits 0–5 of the TLB allocation address (AA[5–0]) have this address format. The
remaining TLB allocation address bits (AA[15–6]) are ignored on updates and always read as zero.
When the MMUAR register is used for a TLB address, bits FA[5–0] also have this address format. The
remaining form address bits (FA[31–6]) are ignored when this register is used for a TLB address.
JADDR, J Control
TLB Hit
entries
Comp
TLB tag
entries
TLB data
entry
TLB hit
data
KC1
J
Translated address
MMU’s access control
Untranslated address
mapping register’s
access control
Mapping register hit
or special mode access
To processor local bus memory controllers
To processor local bus
control for TLB miss
logic
To processor local bus
control for TLB miss
logic
To processor local bus
memory controllers plus
internal-to-external memory
bus interface
Memory unit access control
(MMUBAR, RAMBAR, ACRs, CACR
priority hit logic)
KC1 cycle address control
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...