ADSP-BF53x/BF56x Blackfin Processor Programming Reference
6-51
Memory
“Exceptions” on page 4-47
for more information). The handler is typically
part of the operating system (OS) kernel that implements the CPLB
replacement policy.
L
Before CPLBs are enabled, valid CPLB descriptors must be in place
for both the Page Descriptor Table and the MMU exception han-
dler. The
LOCK
bits of these CPLB descriptors are commonly set so
they are not inadvertently replaced in software.
The handler uses the faulting address to index into the Page Descriptor
Table structure to find the correct CPLB descriptor data to load into one
of the on-chip CPLB register pairs. If all on-chip registers contain valid
CPLB entries, the handler selects one of the descriptors to be replaced,
and the new descriptor information is loaded. Before loading new descrip-
tor data into any CPLBs, the corresponding group of sixteen CPLBs must
be disabled using:
• The Enable DCPLB (
ENDCPLB
) bit in the
DMEM_CONTROL
register for
data descriptors, or
• The Enable ICPLB (
ENICPLB
) bit in the
IMEM_CONTROL
register for
instruction descriptors
The CPLB replacement policy and algorithm to be used are the responsi-
bility of the system MMU exception handler. This policy, which is
dictated by the characteristics of the operating system, usually implements
a modified LRU (Least Recently Used) policy, a round robin scheduling
method, or pseudo random replacement.
After the new CPLB descriptor is loaded, the exception handler returns,
and the faulting memory operation is restarted. this operation should now
find a valid CPLB descriptor for the requested address, and it should pro-
ceed normally.
Содержание ADSP-BF53x Blackfin
Страница 38: ...Conventions xxxviii ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 134: ...System Reset and Powerup 3 18 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 324: ...Instruction Overview 7 20 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 486: ...Instruction Overview 13 28 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 512: ...Instruction Overview 14 26 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 604: ...Instruction Overview 15 92 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 688: ...Instruction Overview 18 48 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 742: ...Instruction Overview 19 54 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 752: ...Examples 20 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 780: ...Product Identification Register 21 28 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 790: ...ADSP BF535 Flags A 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 800: ...Performance Monitor Registers B 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 994: ...Instructions Listed By Operation Code C 194 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 1042: ...Index I 40 ADSP BF53x BF56x Blackfin Processor Programming Reference...