ARM R4 Manuale Utente
Debug
ARM DDI 0363E
Copyright © 2009 ARM Limited. All rights reserved.
11-21
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11.4.9
Debug State Cache Control Register
The DSCCR controls the L1 cache behavior when the processor is in debug state.
Figure 11-8 shows the bit arrangement of the DSCCR.
Figure 11-8 Debug State Cache Control Register format
For information on the usage model of the DSCCR register, see Cache debug on page 11-50.
Table 11-14 shows how the bit values correspond with the Debug State Cache Control Register
functions.
functions.
11.4.10 Instruction Transfer Register
The ITR enables the external debugger to feed instructions into the processor for execution
while in debug state. The ITR is a write-only register. Reads from the ITR return an
Unpredictable value.
while in debug state. The ITR is a write-only register. Reads from the ITR return an
Unpredictable value.
The Instruction Transfer Register, bits [31:0] contain the ARM instruction for the processor to
execute while in debug state. The reset value of this register is Unpredictable.
execute while in debug state. The reset value of this register is Unpredictable.
Note
Writes to the ITR when the processor is not in debug state or the DSCR[13] execute instruction
enable bit is cleared are Unpredictable. When an instruction is issued to the processor, the debug
unit prevents the next instruction from being issued until the DSCR[25] instruction complete bit
is set.
enable bit is cleared are Unpredictable. When an instruction is issued to the processor, the debug
unit prevents the next instruction from being issued until the DSCR[25] instruction complete bit
is set.
31
2 1
31
0
Not write-through
Reserved
3
Instruction cache line-fill
Data cache line-fill
Table 11-14 Debug State Cache Control Register functions
Bits
Field
Reset
value
value
Description
[31:3]
Reserved
0
Reserved. Do not modify on writes. On reads, the value returns zero.
[2]
nWT
0
Not write-through:
1 = normal operation of regions marked as write-back in debug state
0 = force write-through behavior for regions marked as write-back in debug state, this is
the reset value.
1 = normal operation of regions marked as write-back in debug state
0 = force write-through behavior for regions marked as write-back in debug state, this is
the reset value.
[1]
nIL
0
Instruction cache line-fill:
1 = normal operation of L1 instruction cache in debug state
0 = L1 instruction cache line-fills disabled in debug state, this is the reset value.
1 = normal operation of L1 instruction cache in debug state
0 = L1 instruction cache line-fills disabled in debug state, this is the reset value.
[0]
nDL
0
Data cache line-fill:
1 = normal operation of L1 data cache in debug state
0 = L1 data cache line-fills disabled in debug state, this is the reset value.
1 = normal operation of L1 data cache in debug state
0 = L1 data cache line-fills disabled in debug state, this is the reset value.