convert img into vmdk (oracle vmware) or vhd (microsoft pc2007)
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ref: https://docs.openstack.org/image-guide/convert-images.html
pkg search qemu
qemu: QEMU CPU Emulator
pkg install qemu

qemu-img convert -f vmdk -O raw image.vmdk _.disk.full
qemu-img convert -f vpc -O raw image.vhd _.disk.full

http://markelov.org/wiki/index.php?title=Testing_nanoBSD_image_using_VMWare
https://www.freebsd.org/doc/handbook/kernelconfig.html

simulator
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microsoft pc2007 (old windows)
VirtualBox
qemu

cd /usr/src/tools/tools/nanobsd/embedded
cat README
sh ../nanobsd.sh -c i386.conf