Section 6 Memory Management Unit (MMU)
Rev. 1.00 Oct. 01, 2007 Page 138 of 1956
REJ09B0256-0100
When address translation from virtual memory to physical memory is performed using the MMU,
it may happen that the translation information has not been recorded in the MMU, or the virtual
memory of a different process is accessed by mistake. In such cases, the MMU will generate an
exception, change the physical memory mapping, and record the new address translation
information.
Although the functions of the MMU could be implemented by software alone, having address
translation performed by software each time a process accessed physical memory would be very
inefficient. For this reason, a buffer for address translation (the translation lookaside buffer: TLB)
is provided by hardware, and frequently used address translation information is placed here. The
TLB can be described as a cache for address translation information. However, unlike a cache, if
address translation fails—that is, if an exception occurs—switching of the address translation
information is normally performed by software. Thus memory management can be performed in a
flexible manner by software.
There are two methods by which the MMU can perform mapping from virtual memory to physical
memory: the paging method, using fixed-length address translation, and the segment method,
using variable-length address translation. With the paging method, the unit of translation is a
fixed-size address space called a page.
In the following descriptions, the address space in virtual memory in this LSI is referred to as
virtual address space, and the address space in physical memory as physical address space.
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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