Tried to install SNO on a virtual machine with 6 cores, hyperthreading disabled. That should work, as according to the docs, SNO min sys requirements is 8 vCPU, which equals 4 physical cores. https://docs.openshift.com/container-platform/4.17/installing/installing_sno/install-sno-preparing-to-install-sno.html     

4.17.12, 4.18.0.rc.9    

always    

    1. create VM with hyperthreading disabled. lscpu on the machine shows something like:
    Thread(s) per core:   1
    Core(s) per socket:   6
    Socket(s):            1
    2. Use agent based installer to install SNO on this VM. Install fails with error message 
    3.
    

Installation fails with error message `Require at least 8 CPU cores for master role`    

Installation should succeed    

The HW_VALIDATOR_REQUIREMENTS seems to be wrong: https://github.com/openshift/installer/blob/410ff9467a969e627f469b2b3576a0409ed05ec9/data/data/agent/files/usr/local/share/assisted-service/assisted-service.env.template

shows 8 cores for SNO. If this is really physical cores, based on lscpu output, then this has to be 4 instead of 8.  It seems to be physical cores, because the number 4 for a default master installation in a compact cluster is correct.