SUBSYSTEMS=="usb", ATTRS{idVendor}=="feed", MODE:="0666"
```
+### Serial device is not detected in bootloader mode on Linux
+Make sure your kernel has appropriate support for your device. If your device uses USB ACM, such as
+Pro Micro (Atmega32u4), make sure to include `CONFIG_USB_ACM=y`. Other devices may require `USB_SERIAL` and any of its sub options.
+
## Unknown Device for DFU Bootloader
If you're using Windows to flash your keyboard, and you are running into issues, check the Device Manager. If you see an "Unknown Device" when the keyboard is in "bootloader mode", then you may have a driver issue.
```
brew rm avr-gcc
brew rm dfu-programmer
+brew rm dfu-util
brew rm gcc-arm-none-eabi
brew rm avrdude
brew install avr-gcc
brew install dfu-programmer
+brew install dfu-util
brew install gcc-arm-none-eabi
brew install avrdude
```
```
brew uninstall --force avr-gcc
brew install avr-gcc@7
-brew link avr-gcc@7
+brew link --force avr-gcc@7
```