Built and booted several times using both release.sh and bare `make release`.
Generated images available at https://people.freebsd.org/~mhorne/riscv_images/
Can be booted with `sysutils/opensbi` and `sysutils/u-boot-qemu-riscv64` as follows:
```
$ qemu-system-riscv64 -smp 2 -m 2048m -machine virt -nographic \
-bios /usr/local/share/opensbi/lp64/generic/firmware/fw_jump.elf \
-kernel /usr/local/share/u-boot/u-boot-qemu-riscv64/u-boot.bin \
-drive file=FreeBSD-13.0-CURRENT-riscv-riscv64.raw,format=raw,id=hd0 \
-device virtio-blk-device,drive=hd0
```
and for tap networking add:
```
-netdev tap,ifname=tap0,script=no,id=net0 -device virtio-net-device,netdev=net0
```