Simu, instlegato

on legato-19.11.2 “simu start” uses swi-virt-x86,
on legato-18.10.3 “simu start” uses swi-virt-arm
and
simu instlegato
ls: cannot access ‘/home/costa/modular/legato/build/virt/system.*.update’: No such file or directory

Q: How to use simu properly, including instlegato?