Update: Ubuntu 18.04 LTS under #OpenBSD VMM “how to”… 
So, everything you read on the ‘net is, fundamentally, rubbish 
Just grab the “mini.iso” image, create a dastardly disk and then
vmctl start banana -d mini.iso -d LeDisk.img -n transit -n nottransit -c
Then, once booted, select “command line install”, TAB, edit to change vga=off and, at the end, console=ttyS0,115200u8.
Install in peace. 
@trondd you did not read my toot did you?
1) You need to select “Command Line Install” (2nd down)
2) press TAB to edit the command line
3) *edit* the command line to change vga=off and add console=ttyS0,115200u8 at the end
4) press Enter.
@cynicalsecurity I sure did. Wasn't so much "edit" as it was "delete and replace".
It just doesn't like arrow keys.
@trondd ah yes 
I omitted that “detail”… and it doesn’t like c&p either… 
I apologise 
@cynicalsecurity doing god's work
@cynicalsecurity A small note for AMD SVM users, in addition to specifying the console=ttyS0 line, you need to include 'nospec_store_bypass_disable', otherwise the kernel will panic quite quickly after boot.
Note: add -m 2G for a Ubuntu install if you don’t want to wait forever as it dies without enough RAM