MI3/MI4 Protocol Upgrade

Overview

This codebase has been upgraded to support GDB Machine Interface versions 3 and 4 (MI3/MI4), while maintaining backward compatibility with MI2.

Changes Made

1. Enhanced Breakpoint Parsing (`src/backend/mi2/mi2.ts`)

Important Note on MI Protocol: This extension continues to use the MI2 interpreter (--interpreter=mi2) when launching GDB. The changes made are for output format compatibility, not a protocol upgrade. The MI2 parser has been enhanced to accept and correctly parse MI3/MI4-style output formats (such as multi-location breakpoints and script-as-list fields) that newer GDB versions may produce, ensuring forward compatibility without changing the runtime interpreter.

Problem:

MI3 (GDB 9+) changed the output format for multi-location breakpoints
MI4 (GDB 12+) changed the "script" field to be a list instead of a string
The MI2 parser needed to handle these newer output formats

Solution: The addBreakPoint() method now handles both single and multi-location breakpoints:

// Handles both formats:
// MI2: bkpt={number="1",...}
// MI3 single: bkpt={number="1",...}
// MI3 multi-location: bkpt={number="2",locations=[{number="2.1",...}]}
//   Note: Parent bkpt object always exists with parent number

The code first tries to parse the parent breakpoint number (which exists in all cases), and only falls back to reading the first location number if the parent number is invalid.

2. MI Async Mode

Added gdb-set mi-async on during initialization to ensure proper async behavior with modern GDB versions.

Compatibility

Supported GDB Versions

GDB 7.x - 8.x: MI2 (legacy support)
GDB 9.x - 11.x: MI3 (multi-location breakpoint fixes)
GDB 12.x+: MI4 (script field as list)

Supported OpenOCD Versions

OpenOCD 0.10.0+: All versions supported
OpenOCD 0.12.0+: Recommended for best compatibility

Testing Recommendations

Multi-location breakpoints: Test with template functions or inline functions that generate multiple breakpoint locations
Conditional breakpoints: Verify conditions work correctly
Breakpoint scripts: Test breakpoints with commands (MI4 specific)

Known Limitations

The code uses a fallback approach for breakpoint number extraction, which should work across all MI versions
Script field parsing (MI4) is handled by the existing parser but may need additional validation for complex scripts

Migration Notes

No configuration changes are required. The code automatically adapts to the MI version used by the connected GDB instance.

For Users

If you experience issues with breakpoints:

Check your GDB version: gdb --version
Ensure GDB is version 7.0 or newer
For best results, use GDB 12.0+ with MI4 support

For Developers

The MI parser (src/backend/mi_parse.ts) is version-agnostic and handles all MI output formats. The key changes are in how we extract breakpoint information from the parsed results.

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