How to use Hyper-V to debug using KdCOM from 2 VMs, one debugging the other.
Debuggee
Follow the setup here to setup a BCD profile for KdCom in the VM. Shutdown the VM and in a privileged prompt on the host (here assigned to COM1):
Set-VMComPort MyDebuggedVM 1 \\.\pipe\win7x64-kdcom
Debugger
Still on a privileged prompt on the host, choose a COM port number and connect it to the same pipe:
Set-VMComPort MyDebuggerVM 1 \\.\pipe\win7x64-kdcom
Boot the debugger and make WinDbgX listen to that port
windbgx -k com:pipe,port=\\.\com1,resets=0,reconnect
Enjoy
