SPRAD28 October   2022 AM2431 , AM2432 , AM2434 , AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1 , AM263P4 , AM263P4-Q1 , AM26C31 , AM26C31-EP , AM26C31M , AM26C32 , AM26C32-EP , AM26C32C , AM26C32M , AM26LS31 , AM26LS31M , AM26LS32A , AM26LS32AC , AM26LS32AM , AM26LS33A , AM26LS33A-SP , AM26LS33AM , AM26LV31 , AM26LV31E , AM26LV31E-EP , AM26LV32 , AM26LV32E , AM26LV32E-EP , AM26S10 , AM2732 , AM2732-Q1

 

  1.   Abstract
  2.   Trademarks
  3. 1 Building for Debug
    1. 1.1 Disable Code Optimization
    2. 1.2 Using the Debug SDK Libraries
  4. 2 Code Composer Studio Stop-Mode Debugging
    1. 2.1 Configuring the Debugger
    2. 2.2 Breakpoints and Watchpoints
      1. 2.2.1 Software Breakpoints
      2. 2.2.2 Hardware Breakpoints
      3. 2.2.3 Watchpoints
    3. 2.3 Inspecting Device Registers
    4. 2.4 Inspecting Disassembly
  5. 3 Debug Logging
    1. 3.1 Logging Methods
    2. 3.2 Log Zones
    3. 3.3 Asserts
    4. 3.4 Example Usage
  6. 4 Multi-Core Debug
    1. 4.1 Grouping Cores
      1. 4.1.1 Fixed Group
      2. 4.1.2 Hiding Cores
    2. 4.2 Using Multiple Workbench Windows
    3. 4.3 Global Breakpoints
  7. 5 Debugging Arm Cortex-R5 Exceptions
    1. 5.1 Exception Priority Order
    2. 5.2 Aborts
      1. 5.2.1 Data Aborts
        1. 5.2.1.1 Alignment
        2. 5.2.1.2 Background Aborts
        3. 5.2.1.3 Permission
        4. 5.2.1.4 Synchronous/Asynchronous External
        5. 5.2.1.5 Synchronous/Asynchronous ECC
      2. 5.2.2 Synchronous/Asynchronous Aborts
        1. 5.2.2.1 Changing an Asynchronous Abort to a Synchronous Abort
        2. 5.2.2.2 Synchronous Abort
        3. 5.2.2.3 Asynchronous Abort
        4. 5.2.2.4 Debugging Asynchronous Abort
      3. 5.2.3 Prefetch Abort
        1. 5.2.3.1 Possible Reasons for Prefetch Abort
        2. 5.2.3.2 Handling Prefetch Abort Exception
      4. 5.2.4 Undefined Instruction
        1. 5.2.4.1 Possible Reasons for Undefined Instruction Exception
        2. 5.2.4.2 Handling Undefined Instruction Exception
    3. 5.3 Fetching Core Registers Inside an Abort Handler
  8. 6 Debugging Arm Cortex-M4 Exceptions
    1. 6.1 Exception Entry and Exit Sequence
      1. 6.1.1 Entry Sequence
      2. 6.1.2 Exception Exit Sequence
      3. 6.1.3 Decoding EXC_RETURN Value
    2. 6.2 Faults Handling
      1. 6.2.1 There are 15 System Exceptions by Arm Cortex M Processors
        1. 6.2.1.1 Causes of Faults
      2. 6.2.2 HardFault Exception
        1. 6.2.2.1 Causes of HardFault Exception
      3. 6.2.3 Configurable Fault Exceptions
        1. 6.2.3.1 Mem Manage Fault Exception
        2. 6.2.3.2 BusFault Exception
        3. 6.2.3.3 Usage Fault Exception
      4. 6.2.4 Control Registers
        1. 6.2.4.1 SHP - System Handler Priority Register
      5. 6.2.5 Status Registers
        1. 6.2.5.1 Undefined Instruction Handling Example
        2. 6.2.5.2 Invalid State Handling Example
      6. 6.2.6 Printing the Stack Frame
  9. 7 Debugging Memory
    1. 7.1 Viewing Device Memory
    2. 7.2 Linker Command File (linker.cmd)
      1. 7.2.1 The Memory Directive
      2. 7.2.2 The Sections Directive
    3. 7.3 Stack Overflow
      1. 7.3.1 -fstack-protector
      2. 7.3.2 -fstack-protector-strong
      3. 7.3.3 -fstack-protector-all
      4. 7.3.4 Enabling Stack Smashing Detection
      5. 7.3.5 Enabling Stack Smashing Detection
    4. 7.4 Variables and Expressions View in CCS
    5. 7.5 Understanding Your Application's Memory Allocation
    6. 7.6 FreeRTOS ROV
  10. 8 Debugging Boot
    1. 8.1 ROM Boot
    2. 8.2 SBL Boot
    3. 8.3 GEL Files
      1. 8.3.1 Debugging Init Code
        1. 8.3.1.1 Disable Auto-Run to Main
  11. 9 Debugging Real-Time Control Loops
    1. 9.1 Trace
      1. 9.1.1 Processor / Core Trace
      2. 9.1.2 How to Use CCS to Capture Trace Data on an AM243x
    2. 9.2 Code Profile / Coverage
      1. 9.2.1 CCS Count Event
    3. 9.3 Real-Time UART Monitor
      1. 9.3.1 Confirm CCS Features
      2. 9.3.2 Create Target Configuration File
      3. 9.3.3 Add Serial Command Monitor Software
      4. 9.3.4 Launch Real Time Debug
  12. 10E2E Support Forums

5.2.3 Prefetch Abort

Prefetch Abort (PABT) Exception occurs when an instruction fetch causes an error. When a Prefetch Abort occurs, the processor marks the prefetched instruction as invalid, but does not take the exception until the instruction is to be executed. If the instruction is not executed, for example because a branch occurs while it is in the pipeline, an abort does not occur. All prefetch aborts are synchronous. The difference between Undefined Instruction Abort and Prefetch Abort exception is that in case of prefetch, CPU is unable to fetch the instruction from the address; in an Undefined Instruction Exception, the CPU does not know what the instruction does.

The reason for Prefetch Abort can be analyzed by reading the Instruction Fault Status Register (IFSR), the Instruction Fault Address Register (IFAR), and the Auxiliary Instruction Fault Status Register (AIFSR).

GUID-20220325-SS0I-QXS4-XJV2-SQKQ5472Q7PR-low.jpg

IFAR contains the address where the CPU was trying to fetch an instruction from. The contents of IFAR is always valid for a Prefetch Abort, because all Prefetch Aborts are synchronous. AIFSR records additional information about the nature and location of the fault, for example ATCM or BTCM.