Cortex-A8 Technical Reference Manual - ARM Information Center

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12.11 Using the debug functionality Debug This section provides some examples of using the debug functionality, both from the point of view of a software engineer writing code to run on an ARM processor and of a developer creating debug tools for the processor. In the former case, examples are given in ARM assembly language. In the latter case, the examples are in C pseudo-language, intended to convey the algorithms to be used. These examples are not intended as source code for a debugger. The debugger examples use a pair of pseudo-functions such as the following: uint32 ReadDebugRegister(int reg_num) { // read the value of the debug register reg_num at address reg_num > 2 } 12.11.1 Debug communications channel A basic function for using the debug state is executing an instruction through the ITR. Example 12-1 shows the sequence for executing an ARM instruction through the ITR. ExecuteARMInstruction(uint32 instr) { // Step 1. Poll DSCR until InstrCompl is set to 1. repeat { dscr := ReadDebugRegister(34); } until (dscr & (1
Rules for accessing the DCC At the core side, the debug communications channel resources are: • CP14 Debug Register c5 (DTR) • CP14 Debug Register c1 (DSCR). Implementations of the ARMv7 debug for the processor are so that: Debug • If a read of the CP14 DSCR returns 1 for the DTRRXfull flag, then a following read of the CP14 DTR returns valid data and DTRRXfull is cleared to 0. No prefetch flush is required between these two CP14 instructions. • If a read of the CP14 DSCR returns 0 for the DTRRXfull flag, then a following read of the CP14 DTR returns an Unpredictable value. • If a read of the CP14 DSCR returns 0 for the DTRTXfull flag, then a following write to the CP14 DTR writes the intended 32-bit word, and sets DTRTXfull to 1. No prefetch flush is required between these two CP14 instructions. • If a read of the CP14 DSCR returns 1 for the DTRTXfull flag, then a following write to the CP14 DTR is Unpredictable. When nonblocking mode is selected for DTR accesses, the following conditions are true for memory-mapped DSCR, memory-mapped DTRRX, and DTRTX registers: • If a read of the memory-mapped DSCR returns 0 for the DTRRXfull flag, then a following write of the memory-mapped DTRRX passes valid data to the processor and sets DTRRXfull to 1. • If a read of the memory-mapped DSCR returns 1 for the DTRRXfull flag, then a following write of the memory-mapped DTRRX is ignored, that is, both DTRRXfull and DTRRX contents are unchanged. • If a read of the memory-mapped DSCR returns 1 for the DTRTXfull flag, then a following read of the memory-mapped DTRTX returns valid data and clears DTRTXfull to 0. • If a read of the memory-mapped DSCR returns 0 for the DTRTXfull flag, then a following read of the memory-mapped DTRTX is ignored, for example, the content of DTRTXfull is unchanged and the read returns an Unpredictable value. Other uses of the DCC resources are not supported by the ARMv7 debug architecture. In particular, ARMv7 debug does not support the following: • polling CP14 DSCR[30:29] flags to access the memory-mapped DTRRX and DTRTX registers • polling memory-mapped DSCR[30:29] flags to access CP14 DTR. Note Using the DCC in any of the nonsupported ways can be subject to race conditions. Software access to the DCC Software running on the processor that sends data to the debugger through the transmit channel can use the following sequence of instructions as shown in Example 12-2. ; r0 -> word to send to the debugger Example 12-2 Transmit data transfer (target end) ARM DDI 0344K Copyright © 2006-2010 ARM Limited. All rights reserved. 12-70 ID060510 Non-Confidential
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Copyright © 2006-2010 ARM Limited.
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Web Address http://www.arm.com ARM
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Contents 2.14 The program status re
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Contents 16.6 Instruction-specific
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List of Tables Table 3-16 Debug Fea
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List of Tables Table 3-136 Secure o
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List of Tables Table 12-59 Values t
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List of Figures Cortex-A8 Technical
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List of Figures Figure 3-77 BTB arr
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List of Figures Figure 15-16 CTI Ch
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About this manual Product revision
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old Highlights interface elements,
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Feedback Feedback on the product Fe
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1.1 About the processor Introductio
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1.3 Components of the processor L1
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1.3.6 NEON 1.3.7 ETM The NEON unit
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1.5 Debug Introduction The processo
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1.7 Configurable options Table 1-1
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Introduction • The various data a
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1.9.6 r2p0-r2p1 1.9.7 r2p1-r2p2 1.9
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Chapter 2 Programmers Model This ch
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2.2 Thumb-2 instruction set Program
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Bits Field Function Programmers Mod
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2.4 Jazelle Extension 2.4.1 Jazelle
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2.5 Security Extensions architectur
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2.6 Advanced SIMD architecture Prog
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2.8 Processor operating states 2.8.
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2.10 Memory formats 2.10.1 Byte-inv
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2.12 Operating modes Programmers Mo
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System and User r0 r1 r2 r3 r4 r5 r
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2.14 The program status registers 2
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2.14.5 The GE[3:0] bits Programmers
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Mode bits Programmers Model M[4:0]
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2.15 Exceptions 2.15.1 Exception en
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2.15.5 Interrupt request 2.15.6 Abo
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This restores both the PC and the C
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2.15.13 Exception priorities Progra
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2.17 Hardware consideration for Sec
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SECMONOUT[78] instruction caches at
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Chapter 3 System Control Coprocesso
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System Control Coprocessor Register
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3.1.3 MMU control and configuration
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3.2 System control coprocessor regi
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CRn Op1 CRm Op2 Register or operati
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3.2.2 c0, Main ID Register System C
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3.2.4 c0, TCM Type Register 3.2.5 c
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3.2.7 c0, Processor Feature Registe
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• accessible in privileged modes
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System Control Coprocessor Table 3-
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Bits Field Function [11:8] L1 Harva
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Bits Field Function [11:8] Harvard
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31 28 27 24 23 20 19 16 15 12 11 8
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Table 3-30 shows the results of att
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System Control Coprocessor 31 28 27
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Table 3-36 shows the results of att
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• accessible in privileged modes
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CSSR Size 3.2.24 c0, Cache Size Sel
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System Control Coprocessor 31 30 29
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MCR p15, 0, , c1, c0, 0 ; Write Con
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Bits Field [19] Clock stop request
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Bits Field Security State NS S Tabl
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3.2.28 c1, Secure Configuration Reg
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AW EA Function Table 3-55 shows the
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3.2.32 c2, Translation Table Base R
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System Control Coprocessor Figure 3
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Bits Field Function 3.2.35 c5, Data
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3.2.36 c5, Instruction Fault Status
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3.2.38 c6, Data Fault Address Regis
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System Control Coprocessor Note •
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System Control Coprocessor Figure 3
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3.2.41 c8, TLB operations The data
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Figure 3-38 shows the bit arrangeme
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EN b 3.2.44 c9, Count Enable Clear
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EN b 3.2.46 c9, Software Increment
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EN b 3.2.48 c9, Cycle Count Registe
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EN b Table 3-96 shows the results o
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Value Description 0x44 Any cacheabl
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DBGEN || NIDEN 3.2.51 c9, User Enab
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EN 3.2.53 c9, Interrupt Enable Clea
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Figure 3-48 shows the bit arrangeme
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3.2.55 c9, L2 Cache Auxiliary Contr
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Bits Field Function [8:6] Tag RAM l
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TL bit value 3.2.57 c10, TLB preloa
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The PLE Identification and Status R
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3.2.62 c11, PLE enable commands U b
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Bits Field Function System Control
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U bit PLE bit Table 3-129 shows the
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U bit PLE bit System Control Coproc
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3.2.68 c12, Secure or Nonsecure Vec
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3.2.70 c12, Interrupt Status Regist
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The FCSE PID Register is: • a rea
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TLB CAM read/write TLB ATTR read/wr
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MCR p15 0, , c15, c3, 4 ; I-L1 TLB
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31 27 26 22 21 0 Reserved L1 Data 0
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System Control Coprocessor The L1 H
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3.2.78 c15, L1 data array operation
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Instruction L1 Data 0 register Inst
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Parity/ECC RAM read/write Data RAM
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3.2.82 c15, L2 parity/ECC array ope
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3.2.84 c15, L2 data array operation
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4.1 About unaligned and mixed-endia
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Unaligned Data and Mixed-endian Dat
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Chapter 5 Program Flow Prediction T
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5.2 Predicted instructions Program
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Program Flow Prediction Because ret
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5.4 Guidelines for optimal performa
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5.6 Operating system and predictor
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6.1 About the MMU Memory Management
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6.3 16MB supersection support Memor
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6.5 External aborts 6.5.1 External
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6.7 MMU software-accessible registe
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7.1 About the L1 memory system Leve
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7.2.6 Instruction cache maintenance
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L1 inner policy a L2 outer policy N
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7.5 Data cache features 7.5.1 Data
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7.7 Hardware support for virtual al
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Chapter 8 Level 2 Memory System Thi
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8.2 Cache organization 8.2.1 L2 cac
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8.3 Enabling and disabling the L2 c
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Level 2 Memory System Note It is en
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Level 2 Memory System Note You must
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Lock address : LockAddr Lock free :
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8.7 Parity and error correction cod
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9.1 About the external memory inter
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Integer data and CP14 writes Noncac
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9.4 AXI data read/write transaction
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Noncacheable, or strongly ordered,
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Noncacheable store word Noncacheabl
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LA Last Access External Memory Inte
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10.1 Clock domains 10.1.1 AXI clock
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10.2 Reset domains 10.2.1 Power-on
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REFCLK (PLL input) nPORESET ARESETn
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10.3 Power control 10.3.1 Dynamic p
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Clock, Reset, and Power Control the
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ATB APB I/O clamp I/O clamp L/S = L
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ATB APB I/O clamp I/O clamp LS = Le
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Clock, Reset, and Power Control 3.
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Powering up the debug and ETM domai
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7. Perform a normal software reset
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Clock, Reset, and Power Control 5.
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Chapter 11 Design for Test This cha
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In L1 MBIST Instruction Register Fi
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Note Do not test the CAMBIST arrays
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• number of rows of the L2 data,
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Design for Test Not all row setting
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In Design for Test Figure 11-4 show
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Design for Test When testing the ta
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CLK ARESETn MBISTMODE MBISTSHIFT MB
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End-of-test datalog retrieval Desig
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Pattern N RWRXMARCH 8N Row-fast Sta
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4. rscan array, data_seed = invert.
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3. R_, W, R, decr. 4. rscan data fr
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• the data after pass 1 of XADDRB
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(1 + (2 17)) 2 17 = 4,587,520 cycle
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processor input ports WEXTEST WINTE
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Design for Test toggling during shi
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12.1 Debug systems 12.1.1 Debug hos
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12.2.3 Security extensions and debu
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Instruction Mnemonic Description 12
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12.3.6 Power domains and debug 12.3
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Table 12-5 shows the APB interface
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12.4 Debug register descriptions Te
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MRC p14, 0, , c0, c0, 0 ; Read Debu
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31 30 29 28 27 26 25 24 23 22 21 20
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Page 355 and 356: Bits Access Normal address [2] RW V
Page 357 and 358: 12.4.12 Debug Run Control Register
Page 359 and 360: Table 12-23 shows how the bit value
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Page 363 and 364: Bits Field Function [15:14] Secure
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Page 367 and 368: Debug • The sequence can be aband
Page 369 and 370: 12.5 Management registers Offset Th
Page 371 and 372: Offset Register number Mnemonic Fun
Page 373 and 374: Bits Field Function [5] nDMAIRQ nDM
Page 375 and 376: 12.5.7 Claim Tag Clear Register 12.
Page 377 and 378: 12.5.10 Authentication Status Regis
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Page 381 and 382: 12.6 Debug events 12.6.1 Software d
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Page 385 and 386: Table 12-53 shows the values in the
Page 387 and 388: 12.8 Debug state 12.8.1 Entering de
Page 389 and 390: 12.8.4 Writing to the CPSR in debug
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Page 393 and 394: 12.8.9 Leaving debug state Imprecis
Page 395 and 396: 12.9.3 Cache usage profiling Debug
Page 397 and 398: Note DBGPWRDWNREQ must be tied LOW
Page 399: If software running on the processo
Page 403 and 404: } While the processor is running, i
Page 405 and 406: Debug Table 12-59 Values to write t
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Page 409 and 410: } // Step 1. Update the CPSR value
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Page 413 and 414: Debug Example 12-21 Reading a word
Page 415 and 416: } // Step 9. Check for aborts. abor
Page 417 and 418: 12.12 Debugging systems with energy
Page 419 and 420: MOV r0, r4 POP {r4, pc} Example 12-
Page 421 and 422: Chapter 13 NEON and VFP Programmers
Page 423 and 424: 13.2 General-purpose registers 13.2
Page 425 and 426: 13.3 Short vectors 13.3.1 About reg
Page 427 and 428: 13.3.2 Operations using register ba
Page 429 and 430: NEON and VFP Programmers Model The
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Page 433 and 434: Bits Field Function [12:8] - Reserv
Page 435 and 436: NEON and VFP Programmers Model Tabl
Page 437 and 438: 13.6 Compliance with the IEEE 754 s
Page 439 and 440: Underflow NEON and VFP Programmers
Page 441 and 442: 14.1 About the ETM 14.1.1 ETM featu
Page 443 and 444: 14.1.3 NEON Bridge and bus matrix A
Page 445 and 446: 14.3 ETM register summary The ETM r
Page 447 and 448: Bits Field Function [11:8] Major ET
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See the ETM Architecture Specificat
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Embedded Trace Macrocell Table 14-1
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14.5.3 Enabling events 14.5.4 Addre
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14.7 Context ID tracing Embedded Tr
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14.9 Idle state control Embedded Tr
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Chapter 15 Cross Trigger Interface
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CTICHIN[0] CTICHIN[1] CTICHIN[2] CT
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15.2 Trigger inputs and outputs Tri
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15.3 Connecting asynchronous channe
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15.5 CTI register summary Address o
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15.6 CTI register descriptions This
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15.6.4 CTI Application Trigger Clea
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Table 15-10 shows how the bit value
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15.6.12 ASIC Control Register, ASIC
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15.7 CTI Integration Test Registers
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15.7.4 ITTRIGOUTACK, 0xEF0 15.7.5 I
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Cross Trigger Interface Table 15-26
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15.8.3 Device Type Identifier, 0xFC
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Cross Trigger Interface Table 15-31
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16.1 About instruction cycle timing
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Instruction Cycle Timing Example 16
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Table 16-4 shows the operation of m
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Table 16-9 shows the operation of l
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d. See Load/store instructions on p
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Instruction Cycle Timing Table 16-1
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16.4 Other pipeline-dependent laten
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16.4.5 Conditional instructions Ins
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16.6 Instruction-specific schedulin
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Instruction Cycle Timing VNEG Dd,Dm
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VMLA a VMLS a VMLAa VMLSa VQDMLAa V
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VSLI VSRI 16.6.5 Advanced SIMD floa
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16.6.6 Advanced SIMD byte permute i
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Instruction Table 16-23 shows the o
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Instruction VST3 3-reg (unaligned)
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Instruction VLD3 3-reg (unaligned)
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Instruction Single precision cycles
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• FMACS, FNMACS • FMSCS, FNMSCS
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is dual issued with previous instru
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17.1 About setup and hold times AC
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17.2 AXI interface Table 17-2 shows
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17.3 ATB and CTI interfaces Table 1
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AC Characteristics Table 17-4 Timin
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17.6 L2 preload interface AC Charac
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17.8 Miscellaneous signals AC Chara
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A.1 AXI interface Signal Descriptio
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A.3 MBIST and DFT interface A.3.1 M
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A.4 Preload engine interface Table
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A.6 Miscellaneous signals Table A-7
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Signal I/O Reset Description CFGNMF
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Signal I/O Reset Description DBGNOP
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Appendix B Instruction Mnemonics Th
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Instruction Mnemonics Table B-1 Adv
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Appendix C Revisions This appendix
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Revisions Added text to clarify des
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Glossary This glossary describes so
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Glossary Automatic Test Pattern Gen
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Big-endian memory Memory in which:
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Conditional execution Glossary incl
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Glossary Embedded Trace Macrocell (
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Illegal instruction An instruction
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Glossary NaN Not a number. A symbol
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Glossary Significand The component
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Glossary Watchpoint A watchpoint is
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