Memory Protection and Properties
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ADSP-BF535 Blackfin Processor Hardware Reference
Memory Pages
The 4 GB address space of the ADSP-BF535 processor can be divided into
smaller ranges of memory or I/O referred to as memory pages. Every
address within a page shares the attributes defined for that page. The
ADSP-BF535 architecture supports four different page sizes:
• 1 KB
• 4 KB
• 1 MB
• 4 MB
Different page sizes provide a flexible mechanism for matching the map-
ping of attributes to different kinds of memory and I/O. For example, a
large data structure in memory, such as a video frame buffer, would typi-
cally span a significant address range, as large as 16 MB or more. The
entire address range would typically share the same attributes, such as
access protection and cacheability; therefore, ideally only one descriptor
for the entire range is needed. In the case of the ADSP-BF535 processor,
such a video frame buffer could be mapped using four 4 MB pages.
Conversely, when protecting access to different parts of memory between
programs or tasks running on a system, a small memory granularity is
desirable. If a task uses a data structure that is only 1 KB long and needs to
be protected from other tasks, storing it in a 1 MB page would waste
1 MB minus 1 KB of memory, or 1023 KB, to keep this structure isolated
from other tasks.
Memory Page Attributes
Each page is defined by a two-word descriptor, consisting of an address
descriptor word
xCPLB_ADDR[n
] and a properties descriptor word
xCPLB_DATA[n]
. The address descriptor word provides the base address of
the page in memory. Pages must be aligned on page boundaries that are an
Содержание ADSP-BF535 Blackfin
Страница 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Страница 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 908: ...SDRAM Controller External Bus Interface Unit B 36 ADSP BF535 Blackfin Processor Hardware Reference...