Rev. 2.00, 09/03, page 80 of 690
3.3.4
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 on-chip module control registers 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 3.1.
Table 3.1
Access States Designated by D, C, and PR Bits
Privileged Mode
User Mode
Reading
Writing
Reading
Writing
D bit
0
Permitted
Initial page write
exception
Permitted
Initial page write
exception
1
Permitted
Permitted
Permitted
Permitted
C bit
0
Permitted
(no caching)
Permitted
(no caching)
Permitted
(no caching)
Permitted
(no caching)
1
Permitted
(with caching)
Permitted
(with caching)
Permitted
(with caching)
Permitted
(with caching)
PR bit
00
Permitted
TLB protection
violation exception
TLB protection
violation
exception
TLB protection
violation exception
01
Permitted
Permitted
TLB protection
violation
exception
TLB protection
violation exception
10
Permitted
TLB protection
violation exception
Permitted
TLB protection
violation exception
11
Permitted
Permitted
Permitted
Permitted
Summary of Contents for SH7705
Page 2: ......
Page 70: ...Rev 2 00 09 03 page 24 of 690 ...
Page 194: ...Rev 2 00 09 03 page 148 of 690 ...
Page 284: ...Rev 2 00 09 03 page 238 of 690 ...
Page 338: ...Rev 2 00 09 03 page 292 of 690 ...
Page 354: ...Rev 2 00 09 03 page 308 of 690 ...
Page 374: ...Rev 2 00 09 03 page 328 of 690 ...
Page 420: ...Rev 2 00 09 03 page 374 of 690 ...
Page 476: ...Rev 2 00 09 03 page 430 of 690 ...
Page 482: ...Rev 2 00 09 03 page 436 of 690 ...
Page 552: ...Rev 2 00 09 03 page 506 of 690 ...
Page 630: ...Rev 2 00 09 03 page 584 of 690 ...
Page 739: ...SH7705 Group Hardware Manual REJ09B0082 0200O ...