it all seems like yoshimi isn't providing an alsa-midi (aka. alsa-sequencer) input interface for you to connect your midi controller ootb.
reasons for this might be in your particular yoshimi build version or might well be an definitive to yoshimi port development option. either way, what you need is jack-midi to alsa-midi bridge. you can opt to run the one internal to jackd (-Xseq) on Setup/Settings/MIDI Driver = "seq" or use the awesome a2jmidid utility.
please note that the later is the overall recommended way. you can run it from qjackctl with the spell in Setup/Options/Execute script after startup = "a2jmidid -e &". after that, everytime you start jack from qjackctl it will also run the a2jmidid bridge and there you'll be able to see and connect your stuff from the (jack-)midi connections tab while looking under the a2j client name.
it all seems like yoshimi isn't providing an alsa-midi (aka. alsa-sequencer) input interface for you to connect your midi controller ootb.
reasons for this might be in your particular yoshimi build version or might well be an definitive to yoshimi port development option. either way, what you need is jack-midi to alsa-midi bridge. you can opt to run the one internal to jackd (
-Xseq) on Setup/Settings/MIDI Driver = "seq" or use the awesome a2jmidid utility.please note that the later is the overall recommended way. you can run it from qjackctl with the spell in Setup/Options/Execute script after startup = "
a2jmidid -e &". after that, everytime you start jack from qjackctl it will also run the a2jmidid bridge and there you'll be able to see and connect your stuff from the (jack-)midi connections tab while looking under thea2jclient name.cheers