SH7710 Datasheet, PDF (240/996 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series

Section 5 Memory Management Unit (MMU)
5.3.4 Page Management Information
In addition to the SH and SZ bits, the page management information of TLB entries also includes
D, C, and PR bits.
The D bit of a TLB entry indicates whether the page is dirty (i.e., has been written to). If the D bit
is 0, an attempt to write to the page results in an initial page write exception. For physical page
swapping between secondary memory and main memory, for example, pages are controlled so that
a dirty page is paged out of main memory only after that page is written back to secondary
memory. To record that there has been a write to a given page in the address translation table in
memory, an initial page write exception is used.
The C bit in the entry indicates whether the referenced page resides in a cacheable or non-
cacheable area of memory. When the control registers and on-chip memory in area 1 are mapped,
set the C bit to 0. The PR field specifies the access rights for the page in privileged and user modes
and is used to protect memory. Attempts at non-permitted accesses result in TLB protection
violation exceptions.
Access states designated by the D, C, and PR bits are shown in table 5.1.
Rev. 2.00 Dec. 07, 2005 Page 198 of 950
REJ09B0079-0200