4.3.2 DCU Instructions
Data cache flushes and fills are triggered by load, store and cache control instructions. Cache control
instructions are provided to fill, flush, or invalidate cache blocks.
The following instructions control data cache operations.
deba
Data Cache Block Allocate
Speculatively establishes
a line
in
the cache and marks the line as modified.
If the line is not currently
in
the cache, the line is established and marked as
modified without
actually filling the line from external memory.
If dcba references a non-cachable address,
deba
is treated as a no-op.
If dcba references a cachable address, write-through required (which would
otherwise cause an alignment exception), deba is treated as a no-op.
debf
Data Cache Block Flush
Flushes
a line, if found
in
the cache and marked as modified, to external memory;
the
line is then marked invalid.
If
the line is found
in
the cache and is not marked modified, the line is marked invalid
but is not flushed.
This operation is performed regardless of whether the address is marked cachable.
debi
Data Cache Block Invalidate
debst
debt
debtst
4-10
Invalidates a block, if found
in
the cache, regardless of whether the address is
marked
cachable. Any modified data is not flushed to memory.
This is a
privileged instruction.
Data Cache
Block Store
Stores
a block, if found in the cache and marked as modified, into external memory;
the
block is not invalidated but is no longer marked as modified.
If the block is marked as not modified
in
the cache, no operation is performed.
This operation is performed
regardless of whether the address is marked cachable.
Data Cache Block Touch
Fills a block with data, if the address is cachable and the data is not already
in
the
cache.
If the address is non-cachable, this instruction is a no-op.
Data Cache Block Touch for Store
Implemented identically
to the
debt
instruction for compatibility with compilers and
other
tools.
PPC405GP User's Manual Preliminary
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