Related to QTCREATORBUG-13686, which is really great! Thank you for continuing to work on this.

There is one configuration (which happens to be my primary debug setup) that I think is not covered by these options. I prefer to use a Black Magic Probe (http://www.blacksphere.co.nz/main/index.php/blackmagic) which implements a GDB server directly onboard, and communicates via a virtual serial connection (CDC ACM) to GDB, as an extended-remote target.

So, there is no requirement to start an external GDB server, and it does not appear to be possible to specify an extended-remote target in the current implementation.

For instance, my .gdbinit looks like:

set print pretty on
set mem inaccessible-by-default off

target extended-remote /dev/cu.usbmodemDDD3DFD1
monitor jtag_scan
attach 1

I just discovered these most recent changes from the blog post announcement for Creator 3.4 beta, so I may be a little late But hopefully this configuration can be supported in the current framework.