Switch to ethernet build to avoid WiFi crashes in QEMU

WiFi hardware is not emulated in QEMU and causes firmware crashes during
AP mode initialization. Switched to ethernet build variant.

Changes:
- Use esp32_4MB_M_eth build instead of esp32dev
- This build has WLED_USE_ETHERNET flag enabled
- Disables ESP-NOW with WLED_DISABLE_ESPNOW (requires WiFi)
- Network functionality works via emulated ethernet (open_eth model)
- HTTP server accessible without WiFi hardware

Updated workflow:
- Build firmware with pio run -e esp32_4MB_M_eth
- Updated all artifact paths to use esp32_4MB_M_eth
- Updated PlatformIO cache key

Updated documentation:
- docs/QEMU-ISSUES.md: Added build configuration section explaining why
- e2e-tests/README.md: Updated commands to use ethernet build

This resolves the WiFi initialization crashes reported in CI logs.

Co-authored-by: softhack007 <[email protected]>

Author: Copilot

.github/workflows/qemu-e2e-test.yml

@@ -27,9 +27,9 @@ jobs:
         uses: actions/cache@v4
         with:
           path: ~/.platformio
-          key: ${{ runner.os }}-pio-esp32dev-${{ hashFiles('**/platformio.ini') }}
+          key: ${{ runner.os }}-pio-esp32_4MB_M_eth-${{ hashFiles('**/platformio.ini') }}
           restore-keys: |
-            ${{ runner.os }}-pio-esp32dev-
+            ${{ runner.os }}-pio-esp32_4MB_M_eth-
       
       - name: Set up Python
         uses: actions/setup-python@v5
@@ -52,13 +52,13 @@ jobs:
         run: npm run build
 
       - name: Build ESP32 firmware
-        run: pio run -e esp32dev
+        run: pio run -e esp32_4MB_M_eth
 
       - name: Upload firmware artifacts
         uses: actions/upload-artifact@v4
         with:
           name: esp32-firmware
-          path: .pio/build/esp32dev/
+          path: .pio/build/esp32_4MB_M_eth/
           retention-days: 1
 
   # Job 2: Test with QEMU ESP32
@@ -85,7 +85,7 @@ jobs:
         uses: actions/download-artifact@v4
         with:
           name: esp32-firmware
-          path: .pio/build/esp32dev/
+          path: .pio/build/esp32_4MB_M_eth/
 
       - name: Install Node.js dependencies
         run: npm ci
@@ -116,7 +116,7 @@ jobs:
       - name: Start QEMU with WLED firmware in background
         run: |
           chmod +x .github/scripts/run-qemu.sh
-          bash .github/scripts/run-qemu.sh .pio/build/esp32dev qemu-esp32 8080 > qemu-output.log 2>&1 &
+          bash .github/scripts/run-qemu.sh .pio/build/esp32_4MB_M_eth qemu-esp32 8080 > qemu-output.log 2>&1 &
           echo "Waiting for QEMU to start and WLED to boot..."
           sleep 45
       

docs/QEMU-ISSUES.md

@@ -1,25 +1,38 @@
 # QEMU ESP32 Testing - Known Issues and Limitations
 
+## Build Configuration
+
+**Important**: QEMU testing uses the **ethernet build** (`esp32_4MB_M_eth`) instead of the default WiFi build.
+
+### Why Ethernet Build?
+- WiFi hardware is not emulated in QEMU
+- WiFi initialization causes crashes in QEMU
+- Ethernet build uses `WLED_USE_ETHERNET` flag
+- Disables ESP-NOW with `WLED_DISABLE_ESPNOW` (requires WiFi)
+- Allows network functionality without WiFi hardware
+- HTTP server works via emulated ethernet (open_eth model)
+
 ## QEMU Limitations
 
 ESP32 QEMU emulation is not perfect and has several known limitations:
 
 ### Hardware Emulation
-- **WiFi**: Not fully emulated - WiFi operations may fail or behave differently
+- **WiFi**: Not emulated - **causes crashes if enabled**
 - **Bluetooth**: Not emulated
 - **I2C/SPI**: Limited emulation - some peripherals may not work
 - **GPIO**: Partial emulation - LED outputs and some inputs work, but not all
 - **ADC**: Not emulated
 - **Touch sensors**: Not emulated
 - **RTC**: Limited emulation
+- **Ethernet**: Emulated via open_eth model (used for testing)
 
 ### Common Crash Patterns
 
 #### 1. WiFi-Related Crashes
 **Symptom**: Crashes when trying to initialize WiFi or connect to networks  
 **Cause**: WiFi hardware is not fully emulated in QEMU  
 **Analysis**: Check if crash occurs during WiFi initialization  
-**Solution**: These are expected in QEMU and don't indicate real firmware bugs
+**Solution**: Use ethernet build (`esp32_4MB_M_eth`) which disables WiFi
 
 #### 2. Peripheral Access Crashes
 **Symptom**: Crashes when accessing I2C, SPI, or other peripherals  

e2e-tests/README.md

@@ -31,10 +31,12 @@ pip install -r requirements.txt
 
 Test the actual firmware running in QEMU ESP32 emulator:
 
+**Important**: Use the ethernet build for QEMU testing, as WiFi is not emulated and causes crashes.
+
 1. **Build the firmware**:
    ```bash
    npm run build  # Build web UI
-   pio run -e esp32dev  # Build firmware (takes 15+ minutes first time)
+   pio run -e esp32_4MB_M_eth  # Build ethernet firmware (WiFi disabled, 15+ min first time)
    ```
 
 2. **Setup QEMU** (first time only):
@@ -44,7 +46,7 @@ Test the actual firmware running in QEMU ESP32 emulator:
 
 3. **Run firmware in QEMU** (in a separate terminal):
    ```bash
-   bash .github/scripts/run-qemu.sh .pio/build/esp32dev qemu-esp32 8080
+   bash .github/scripts/run-qemu.sh .pio/build/esp32_4MB_M_eth qemu-esp32 8080
    ```
 
    Wait ~30-45 seconds for ESP32 to boot and start the web server.