gdb_set_breakpoint

Set breakpoints in Nintendo Switch executables for debugging on Yuzu or hardware via GDB. Specify function names, file locations, or memory addresses to pause execution during analysis.

Instructions

Set a breakpoint at a function, file:line, or *address. For offset-from-main breakpoints, use switch_break_at instead.

Input Schema

TableJSON Schema

Name	Required	Description
`location`	Yes	Breakpoint location (function, file:line, or *address)
`condition`	No	Conditional expression
`temporary`	No	Whether breakpoint is temporary

Implementation Reference

src/gdb_multiarch_mcp/gdb_interface.py:828-886 (handler)

The `set_breakpoint` method in `GDBSession` class defines the implementation for setting GDB breakpoints using the `-break-insert` command.

def set_breakpoint(
    self, location: str, condition: Optional[str] = None, temporary: bool = False
) -> dict[str, Any]:
    """
    Set a breakpoint at the specified location.

    Args:
        location: Location (function name, file:line, *address)
        condition: Optional condition expression
        temporary: Whether this is a temporary breakpoint

    Returns:
        Dict with breakpoint information
    """
    cmd_parts = ["-break-insert"]

    if temporary:
        cmd_parts.append("-t")

    if condition:
        # Escape backslashes and quotes in the condition
        escaped_condition = condition.replace("\\", "\\\\").replace('"', '\\"')
        cmd_parts.extend(["-c", f'"{escaped_condition}"'])

    cmd_parts.append(location)

    result = self.execute_command(" ".join(cmd_parts))

    if result["status"] == "error":
        return result

    # The MI result payload is in result["result"]["result"]
    # This contains the actual GDB/MI command result
    mi_result = self._extract_mi_result(result)

    # Debug logging
    logger.debug(f"Breakpoint MI result: {mi_result}")

    if mi_result is None:
        logger.warning(f"No MI result for breakpoint at {location}")
        return {
            "status": "error",
            "message": f"Failed to set breakpoint at {location}: no result from GDB",
            "raw_result": result,
        }

    # The breakpoint data should be in the "bkpt" field
    bp_info = mi_result if isinstance(mi_result, dict) else {}
    breakpoint = bp_info.get("bkpt", bp_info)  # Sometimes it's directly in the result

    if not breakpoint:
        logger.warning(f"Empty breakpoint result for {location}: {mi_result}")
        return {
            "status": "error",
            "message": f"Breakpoint set but no info returned for {location}",
            "raw_result": result,
        }

    return {"status": "success", "breakpoint": breakpoint}

src/gdb_multiarch_mcp/server.py:479-483 (handler)

The `call_tool` handler in `server.py` delegates the `gdb_set_breakpoint` tool call to `session.set_breakpoint`.

elif name == "gdb_set_breakpoint":
    a = SetBreakpointArgs(**arguments)
    result = session.set_breakpoint(
        location=a.location, condition=a.condition, temporary=a.temporary
    )

gdb-multiarch-mcp