Feature enhancement: serial ports should have a telnet listener config option

[gwr]

The serial port emulated for VirtualBox guests currently supports only one interface to the hosting system, which is a "UNIX domain" socket. It would be more convenient if instead, or in addition, VirtualBox supported listening on localhost:port, i.e. 127.0.0.1:789, where the port number is configurable similar to the current "pipe name" setting.

This should allow a local "telnet localhost 789" command to connect to the console on the guest OS, removing the need to download and build "socat" or similar utilities.

This should also enable the _very_important_ ability to send a "line break" to the guest OS, which is needed to "break into" the debugger on Solaris (and some others). With the telnet client, and typical console servers, one can send the local telnet escape, and then do "send brk" to cause the generation of a serial "line break" on the console.

[Sander van Leeuwen]

I don't really see why we should invest time if you can just use 3rd party utilities to do the job.

In the next major version you'll be also able to inject NMIs into the guest (VT-x/AMD-V only) to activate the Solaris kernel debugger.

[gwr]

I'm sitting here with a hung (virtual) test machine today. I'd really like to have that NMI feature, or if we had the telnet feature requested by this ticket, I'd just do

esc-right-bracket, send brk

and i'd be into kmdb on the serial line...

[aeichner]

Recent versions of VirtualBox support injection of an NMI. Just execute VBoxManage controlvm <VM name> injectnmi

[Technologov]

Duplicate of wish #1851

-Technologov