Background: Anybody playing with Arduino / ESP32 uses esptool.py (often indirectly). It is a tool that talks to a USB connected ardiuno or esp32 device and can do useful things like reset, flash (download a new firmware), etc. It does this magic by talking to a USB<->serial bridge chip on the development board. These chips are typically either a CP210x from Silicon Labs or something from Future Tech Development (ftdi). The magic comes from the script manipulating the DTR and RTS lines on the serial port to toggle boot mode and reset the device (the boot mode providing a ROM bootloader). I have been unable to make this work under Parallels. A work colleague has demonstrated it working on a "real" PC running exactly the same Linux (Mint 20.2 fwiw). So I'm left wondering wtf... I'm on an imac running big sur running parallels 17.1.0 (51516). Any ideas welcome.