Xilinx Virtex-II Pro PPC405, User Manual

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Virtex-II Pro™ Platform FPGA Documentation 1-800-255-7778
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(writes) by the debug mechanism. Instructions that can cause loss of data
through invalidation are also treated as stores. Both types of instructions
can cause DAC-write events. Instructions in this category are
dcbi and
dcbz .
• Cache-control instructions that invalidate unmodified are treated as
loads. These instructions can cause DAC-read events but not DAC-write
events. The
icbi
instruction falls in this category.
• Cache-control instructions that are not address specific do not cause DAC
events. Instructions in this category are
dccci , iccci , dcread , and icread .
• Cache-control instructions that update system memory with data already
present in the cache are treated as loads (reads) by the access-protection
mechanism. However, the debug mechanism can be used to cause a
DAC-write event when these instructions are executed. Instructions in
this category are
dcbf
and
dcbst
.
• Cache-control instructions that are speculative are treated as loads by the
debug mechanism. These instructions can cause DAC-read events.
Instructions in this category are
dcbt , dcbtst , and icbt .
• Cache-control instructions that allocate cachelines are treated as stores.
These instructions can cause DAC-write events. The
dcba instruction falls
in this category.
Table 9-10 summarizes the type of DAC event that can occur for each cache-
control instruction.
Data Value-Compare Debug Event
A data value-compare (DVC) debug event occurs when:
1. A DAC match occurs. The operand effective-address of the data-access
instruction must match the value contained in one of the DAC
n registers,
using the conditions specified by the DBCR1 register.
Table 9-10: DAC Events Caused by Cache-Control Instructions
Instruction DAC Read DAC Write
dcba No Yes
dcbf No Yes
dcbi No Yes
dcbst No Yes
dcbt Yes No
dcbtst Yes No
dcbz No Yes
dccci Does not cause DAC events.
dcread Does not cause DAC events.
icbi Yes No
icbt Yes No
iccci Does not cause DAC events.
icread Does not cause DAC events.