- Prerequisites & Background Knowledge:
When you run the 'arduino-cli compile --upload blink/sketch' command,
a 'sketch.ino_debug.elf' file for debugging is created in the cache
folder. The 'sketch.ino.elf-zsk.bin' file is uploaded to the MCU address
0x08100000. It is then relocated to the SRAM 0x20000000 area by the
'llext_load' function. This relocated information is stored in the SRAM
area as an 'llext' struct, where 'llext->name' contains the value "sketch".
To perform source-level debugging, you need to determine the location of
the 'sketch.ino_debug.elf' file and the '.text', '.rodata', and '.bss'
section values from the 'llext' struct information.
. Location of the 'sketch.ino_debug.elf' file:
1. Generate an MD5 hash of the full path containing the sketch program:
echo -n "/home/arduino/{SKETCH_FOLEDER} | md5sum | awk '{print toupper($1)}'
# echo -n "/home/arduino/works/blink/sketch" | md5sum | awk '{print toupper($1)}'
# EA52F4B169B20C1503833FB344F2E866
2. Path: /home/arduino/.cache/arduino/sketches/{MD5_HASH}/sketch.ino_debug.elf
# /home/arduino/.cache/arduino/sketches/EA52F4B169B20C1503833FB344F2E866/sketch.ino_debug.elf
- Setup: Open 3 Terminals
1) Terminal #1: Used for running OpenOCD and GDB.
2) Terminal #2: Used for Serial/Monitor via the 'arduino-app-cli monitor'
command.
3) Terminal #3: Used for Python to execute 'Bridge.call' and send a
'Bridge.notify' to trigger the function set as a breakpoint.
(The 'arduino' package must be installed in the Python .venv).
1. In Terminal #1, run OpenOCD in the background and launch the
'arm-zephyr-eabi-gdb' program:
/opt/openocd/bin/openocd -s /opt/openocd -f openocd_gpiod.cfg & [Enter][Enter]
# To find the gdb path: find ~/.arduino15 -name "arm-zephyr-eabi-gdb"
# /home/arduino/.arduino15/packages/zephyr/tools/arm-zephyr-eabi/0.16.8/bin/arm-zephyr-eabi-gdb
/home/arduino/.arduino15/packages/zephyr/tools/arm-zephyr-eabi/0.16.8/bin/arm-zephyr-eabi-gdb
1.1. Find the 'llext' struct information:
target extended-remote:3333
monitor reset halt
find 0x20002000, 0x20003000, "sketch"
# print/x $_ + 16
x/4xw $_ + 16
# .text .rodata .bss
# 0x20002068: 0x200021b0 0x00000000 0x200087f4 0x20008cc0
1.2. Remap the symbol tables with the new section information:
add-symbol-file /home/arduino/.cache/arduino/sketches/{MD5_HASH}/sketch.ino_debug.elf 0x200021b0 -s .rodata 0x200087f4 -s .bss 0x20008cc0
(gdb) add-symbol-file /home/arduino/.cache/arduino/sketches/EA52F4B169B20C1503833FB344F2E866/sketch.ino_debug.elf 0x200021b0 -s .rodata 0x200087f4 -s .bss 0x20008cc0
add symbol table from file "/home/arduino/.cache/arduino/sketches/EA52F4B169B20C1503833FB344F2E866/sketch.ino_debug.elf" at
.text_addr = 0x200021b0
.rodata_addr = 0x200087f4
.bss_addr = 0x20008cc0
(y or n) y
1.3. Set a breakpoint and run GDB:
monitor gdb breakpoint_override hard
break sketch_info
# Breakpoint 1 at 0x200022e0: file /home/arduino/works/blink/sketch/sketch.ino, line 69.
continue
2. Run 'Bridge.call(...)' and 'Bridge.notify('sketch_info')' in Python
Terminal #3 to hit the breakpoint:
python
from arduino.app_utils import Bridge
Bridge.call('set_led_state', False)
Bridge.notify('sketch_info')
3. Verify that the execution has stopped at the breakpoint in
Terminal #1 (GDB):
Breakpoint 1, sketch_info () at /home/arduino/works/blink/sketch/sketch.ino:69
69 for (uintptr_t addr = scan_start; addr <= scan_end - sizeof(struct llext); addr +=4) {
Execute the 'next' and 'list' commands. *** Do not use single quotes when
entering commands in GDB.
Execute 'until 72'
Run 'print *candidate'
Run 'print candidate->name'
Execute 'continue'
4. Check the output screen on the Serial/Monitor terminal.
This completes the setup for source-level debugging of your sketch program. Happy debugging!!!
sketch.ino
// SPDX-FileCopyrightText: Copyright (C) ARDUINO SRL (http://www.arduino.cc)
//
// SPDX-License-Identifier: MPL-2.0
#include <zephyr/kernel.h>
#include "Arduino_RouterBridge.h"
#if 1
extern "C" {
#include <zephyr/llext/llext.h>
}
#endif
void setup() {
pinMode(LED_BUILTIN, OUTPUT);
Bridge.begin();
Serial.begin();
Bridge.provide("reset_led_count", reset_led_count);
Bridge.provide("set_led_state", set_led_state);
Bridge.provide("sketch_info", sketch_info);
}
void loop() {
char buffer[83];
if (Serial.available() > 0) {
String s = Serial.readStringUntil('\n');
s.trim();
snprintf(buffer, sizeof(buffer), "\"%s\"", s.c_str());
Serial.print(buffer);
}
k_msleep(10);
}
int count = 0;
void reset_led_count() {
count = 0;
Serial.println("reset count");
}
String set_led_state(bool state) {
char buffer[30]; // Buffer for formatted string
snprintf(buffer, sizeof(buffer), "%4d set_led_state called", ++count); // Format " 1", " 10", etc.
Serial.println(buffer);
// LOW state means LED is ON
digitalWrite(LED_BUILTIN, state ? LOW : HIGH);
String r = digitalRead(LED_BUILTIN) == LOW ? String("ON") : String("OFF");
return r;
}
void sketch_info() {
char buffer[80];
#if 1
uintptr_t scan_start = 0x20002000;
uintptr_t scan_end = 0x20004000;
const char* name = "sketch";
size_t name_len = strlen(name);
struct llext *ext = NULL;
for (uintptr_t addr = scan_start; addr <= scan_end - sizeof(struct llext); addr +=4) {
struct llext *candidate = (struct llext *)addr;
if (strncmp(candidate->name, name, name_len) == 0) {
uintptr_t next_ptr = (uintptr_t)candidate->llext_list.next;
if (next_ptr == 0 || (next_ptr >= 0x20000000 && next_ptr <= 0x200BFFFF)) {
ext = candidate;
break;
}
}
}
if (ext != NULL) {
Serial.println("-------------------------------------------------");
Serial.print("llext : 0x");
Serial.println((uintptr_t)ext, HEX);
// [1] llext->link
snprintf(buffer, sizeof(buffer), " [%p + %d] llext_list : %p", ext, ((uintptr_t)&(ext->llext_list) - (uintptr_t)ext), ext->llext_list);
Serial.println(buffer);
// [2] llext->name
snprintf(buffer, sizeof(buffer), " [%p + %d] name : '%s'", ext, ((uintptr_t)&(ext->name) - (uintptr_t)ext), ext->name);
Serial.println(buffer);
// [3] .text (코드 영역)
uintptr_t text_start = (uintptr_t)ext->mem[LLEXT_MEM_TEXT];
size_t text_size = ext->mem_size[LLEXT_MEM_TEXT];
snprintf(buffer, sizeof(buffer), " [%p + %d] .text : %p %8d", &(ext->mem), LLEXT_MEM_TEXT, text_start, text_size);
Serial.println(buffer);
// [4] .rodata (초기화되지 않은 전역변수 영역)
snprintf(buffer, sizeof(buffer), " [%p + %d] .rodata : %p %8d", &(ext->mem), LLEXT_MEM_RODATA, (uintptr_t)ext->mem[LLEXT_MEM_RODATA], (uintptr_t)ext->mem_size[LLEXT_MEM_RODATA]);
Serial.println(buffer);
// [5] .bss (초기화되지 않은 전역변수 영역)
uintptr_t bss_start = (uintptr_t)ext->mem[LLEXT_MEM_BSS];
size_t bss_size = ext->mem_size[LLEXT_MEM_BSS];
snprintf(buffer, sizeof(buffer), " [%p + %d] .bss : %p %8d", &(ext->mem), LLEXT_MEM_BSS, bss_start, bss_size);
Serial.println(buffer);
Serial.println("-------------------------------------------------");
}
#endif
Serial.println();
snprintf(buffer, sizeof(buffer), "%-20s: %p","main", ((uintptr_t)&main) & ~1);
Serial.println(buffer);
snprintf(buffer, sizeof(buffer), "%-20s: %p"," setup", ((uintptr_t)&setup) & ~1);
Serial.println(buffer);
snprintf(buffer, sizeof(buffer), "%-20s: %p"," loop", ((uintptr_t)&loop) & ~1);
Serial.println(buffer);
snprintf(buffer, sizeof(buffer), "%-20s: %p"," reset_led_count", ((uintptr_t)&reset_led_count) & ~1);
Serial.println(buffer);
snprintf(buffer, sizeof(buffer), "%-20s: %p"," set_led_state", ((uintptr_t)&set_led_state) & ~1);
Serial.println(buffer);
snprintf(buffer, sizeof(buffer), "%-20s: %p"," sketch_info", ((uintptr_t)&sketch_info) & ~1);
Serial.println(buffer);
Serial.println(" ------------------");
snprintf(buffer, sizeof(buffer), "%-20s: %p"," count", &count);
Serial.println(buffer);
}
