When vchans are enabled, the primary channels do not interact with
userland, but with the vchans.
With vchans enabled:
$ sndctl feederchain
dsp0.play.0.feederchain=[vchans -> [...] -> hardware]
dsp0.record.0.feederchain=[hardware -> [...] -> vchans]
With vchans disabled:
dsp0.play.0.feederchain=[userland -> [...] -> hardware]
dsp0.record.0.feederchain=[hardware -> [...] -> userland]
Sponsored by: The FreeBSD Foundation
MFC after: 1 week