Rev. 1.50, 10/04, page 136 of 448
7.4 MMU
Functions
7.4.1
MMU Hardware Management
The SH-4A supports the following MMU functions.
1. The MMU decodes the virtual address to be accessed by software, and performs address
translation by controlling the UTLB/ITLB in accordance with the MMUCR settings.
2. The MMU determines the cache access status on the basis of the page management
information read during address translation (C and WT bits).
3. If address translation cannot be performed normally in a data access or instruction access, the
MMU notifies software by means of an MMU exception.
4. If address translation information is not recorded in the ITLB in an instruction access, the
MMU searches the UTLB. If the necessary address translation information is recorded in the
UTLB, the MMU copies this information into the ITLB in accordance with the LRUI bit
setting in MMUCR.
7.4.2 MMU
Software
Management
Software processing for the MMU consists of the following:
1. Setting of MMU-related registers. Some registers are also partially updated by hardware
automatically.
2. Recording, deletion, and reading of TLB entries. There are two methods of recording UTLB
entries: by using the LDTLB instruction, or by writing directly to the memory-mapped UTLB.
ITLB entries can only be recorded by writing directly to the memory-mapped ITLB. Deleting
or reading UTLB/ITLB entries is enabled by accessing the memory-mapped UTLB/ITLB.
3. MMU exception handling. When an MMU exception occurs, processing is performed based on
information set by hardware.
Summary of Contents for SuperH SH-4A
Page 2: ...Rev 1 50 10 04 page ii of xx ...
Page 8: ...Rev 1 50 10 04 page viii of xx ...
Page 116: ...Rev 1 50 10 04 page 96 of 448 ...
Page 178: ...Rev 1 50 10 04 page 158 of 448 ...
Page 206: ...Rev 1 50 10 04 page 186 of 448 ...
Page 231: ...Rev 1 50 10 04 page 211 of 448 Possible Exceptions Slot illegal instruction exception ...
Page 235: ...Rev 1 50 10 04 page 215 of 448 Possible Exceptions Slot illegal instruction exception ...
Page 238: ...Rev 1 50 10 04 page 218 of 448 Possible Exceptions Slot illegal instruction exception ...
Page 408: ...Rev 1 50 10 04 page 388 of 448 Possible Exceptions Inexact Not generated when FPSCR PR 1 ...
Page 446: ...Rev 1 50 10 04 page 426 of 448 ...
Page 468: ...Rev 1 50 10 04 page 448 of 448 ...
Page 471: ......
Page 472: ...SH 4A Software Manual ...