
. . . . .
W O R K I N G W I T H T H E C P U
MemoryManagement Unit (MMU)
www.digiembedded.com
115
A tiny page descriptor provides the base address of a 1 KB block of memory.
Coarse page tables provide base addresses for either small or large pages. Large
page descriptors must be repeated in 16 consecutive entries. Small page descriptors
must be repeated in each consecutive entry.
Fine page tables provide base addresses for large, small, or tiny pages. Large page
descriptors must be repeated in 64 consecutive entries. Small page descriptors must
be repeated in four consecutive entries. Tiny page descriptors must be repeated in
each consecutive entry.
Second-level
descriptor bit
assignments
Second-level
descriptor least
significant bits
The two least significant bits of the second-level descriptor indicate the descriptor
type, as shown in this table.
Note:
Tiny pages do not support subpage permissions and therefore have only one
set of access permission bits.
Bits
Large
Small
Tiny
Description
[31:16]
[31:12]
[31:10]
Form the corresponding bits of the physical address.
[15:12]
---
[9:6]
SHOULD BE ZERO
[11:4]
[11:4]
[5:4]
Access permission bits. See “Domain access control” on
page 121 and “Fault checking sequence” on page 122 for
information about interpreting the access permission bits.
[3:2]
[3:2]
[3:2]
Indicate whether the area of memory mapped by this page
is treated as write-back cachable, write-through cachable,
noncached buffered, and noncached nonbuffered.
[1:0]
[1:0]
[1:0]
Indicate the page size and validity, and are interpreted as
shown in “First-level descriptor bit assignments:
Interpreting first level descriptor bits [1:0]” on page 111.
Value
Meaning
Description
0 0
Invalid
Generates a page translation fault.
0 1
Large page
Indicates that this is a 64 KB page.
1 0
Small page
Indicates that this is a 4 KB page.
1 1
Tiny page
Indicates that this is a 1 KB page.
Содержание NS9215
Страница 1: ...NS9215 Hardware Reference 90000847_C Release date 10 April 2008...
Страница 3: ......
Страница 4: ......
Страница 26: ...26 Hardware Reference NS9215...
Страница 44: ...P I N O U T 26 5 System clock 44 Hardware Reference NS9215 System clock drawing...
Страница 52: ...P I N O U T 26 5 Power and ground 52 Hardware Reference NS9215...
Страница 80: ...I O C O N T ROL M O D U L E Memory Bus Configuration register 80 Hardware Reference NS9215...
Страница 136: ...WOR KI N G W I TH T H E C P U Noncachable instruction fetches 136 Hardware Reference NS9215...
Страница 202: ...S Y S T E M C O N T RO L M OD U L E RTC Module Control register 202 Hardware Reference NS9215...
Страница 260: ...M E MO R Y C O N T ROL L E R StaticMemory Turn Round Delay 0 3 registers 260 Hardware Reference NS9215...
Страница 354: ...E X T E R N A L D M A DMA Peripheral Chip Select register 354 Hardware Reference NS9215...
Страница 362: ...A E S D AT A E N C R Y P T I O N D E C R Y P T I O N M O D U L E CCM mode 362 Hardware Reference NS9215...
Страница 384: ...I O HU B M OD UL E Module Direct Mode TX Data Last FIFO 384 Hardware Reference NS9215 31 March 2008...
Страница 414: ...S E R I A L C ON T RO L M O D U L E U ART UART Modem Status register 414 Hardware Reference NS9215...
Страница 446: ...S E R I A L C ON T RO L M O D U L E S PI SPI timing characteristics 446 Hardware Reference NS9215...
Страница 472: ...R E A L TI M E C L O C K M O D U L E General Status register 472 Hardware Reference NS9215...
Страница 512: ...TI M I NG Clock timing 512 Hardware Reference NS9215...
Страница 514: ...PA CKA GING Processor Dimensions 514 Hardware Reference NS9215 P r o c e s s o r D i m e n s i o n s...
Страница 515: ...PA CKA GING Processor Dimensions www digiembedded com 515...
Страница 516: ...PA CKA GING Processor Dimensions 516 Hardware Reference NS9215...