Section 6 Memory Management Unit (MMU)
Rev. 1.00 Oct. 01, 2007 Page 165 of 1956
REJ09B0256-0100
6.4.5
Avoiding Synonym Problems
When 1- or 4-Kbyte pages are recorded in TLB entries, a synonym problem may arise. The
problem is that, when a number of virtual addresses are mapped onto a single physical address, the
same physical address data is recorded in a number of cache entries, and it becomes impossible to
guarantee data integrity. This problem does not occur with the instruction TLB and instruction
cache because data is only read in these cases. In this LSI, entry specification is performed using
bits 12 to 5 of the virtual address in order to achieve fast operand cache operation. However, bits
12 to 10 of the virtual address in the case of a 1-Kbyte page, and bit 12 of the virtual address in the
case of a 4-Kbyte page, are subject to address translation. As a result, bits 12 to 10 of the physical
address after translation may differ from bits 12 to 10 of the virtual address.
Consequently, the following restrictions apply to the recording of address translation information
in UTLB entries.
•
When address translation information whereby a number of 1-Kbyte page UTLB entries are
translated into the same physical address is recorded in the UTLB, ensure that the VPN[12:10]
values are the same.
•
When address translation information whereby a number of 4-Kbyte page UTLB entries are
translated into the same physical address is recorded in the UTLB, ensure that the VPN[12]
value is the same.
•
Do not use 1-Kbyte page UTLB entry physical addresses with UTLB entries of a different
page size.
•
Do not use 4-Kbyte page UTLB entry physical addresses with UTLB entries of a different
page size.
The above restrictions apply only when performing accesses using the cache.
Note: When multiple items of address translation information use the same physical memory to
provide for future expansion of the SuperH RISC engine family, ensure that the
VPN[20:10] values are the same. Also, do not use the same physical address for address
translation information of different page sizes.
Summary of Contents for SH7763
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Page 122: ...Section 2 Programming Model Rev 1 00 Oct 01 2007 Page 56 of 1956 REJ09B0256 0100 ...
Page 144: ...Section 3 Instruction Set Rev 1 00 Oct 01 2007 Page 78 of 1956 REJ09B0256 0100 ...
Page 170: ...Section 4 Pipelining Rev 1 00 Oct 01 2007 Page 104 of 1956 REJ09B0256 0100 ...
Page 282: ...Section 7 Caches Rev 1 00 Oct 01 2007 Page 216 of 1956 REJ09B0256 0100 ...
Page 378: ...Section 9 Interrupt Controller INTC Rev 1 00 Oct 01 2007 Page 312 of 1956 REJ09B0256 0100 ...
Page 514: ...Section 12 DDR SDRAM Interface DDRIF Rev 1 00 Oct 01 2007 Page 448 of 1956 REJ09B0256 0100 ...
Page 630: ...Section 13 PCI Controller PCIC Rev 1 00 Oct 01 2007 Page 564 of 1956 REJ09B0256 0100 ...
Page 710: ...Section 16 Clock Pulse Generator CPG Rev 1 00 Oct 01 2007 Page 644 of 1956 REJ09B0256 0100 ...
Page 732: ...Section 17 Watchdog Timer and Reset WDT Rev 1 00 Oct 01 2007 Page 666 of 1956 REJ09B0256 0100 ...
Page 752: ...Section 18 Power Down Mode Rev 1 00 Oct 01 2007 Page 686 of 1956 REJ09B0256 0100 ...
Page 772: ...Section 19 Timer Unit TMU Rev 1 00 Oct 01 2007 Page 706 of 1956 REJ09B0256 0100 ...
Page 824: ...Section 21 Compare Match Timer CMT Rev 1 00 Oct 01 2007 Page 758 of 1956 REJ09B0256 0100 ...
Page 1124: ...Section 26 I 2 C Bus Interface IIC Rev 1 00 Oct 01 2007 Page 1058 of 1956 REJ09B0256 0100 ...
Page 1350: ...Section 30 SIM Card Module SIM Rev 1 00 Oct 01 2007 Page 1284 of 1956 REJ09B0256 0100 ...
Page 1484: ...Section 33 Audio Codec Interface HAC Rev 1 00 Oct 01 2007 Page 1418 of 1956 REJ09B0256 0100 ...
Page 1560: ...Section 35 USB Host Controller USBH Rev 1 00 Oct 01 2007 Page 1494 of 1956 REJ09B0256 0100 ...
Page 1720: ...Section 37 LCD Controller LCDC Rev 1 00 Oct 01 2007 Page 1654 of 1956 REJ09B0256 0100 ...
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