Download the latest disk image
Go to this link for the nightly builds and select the most recent (top) build. Look for the -sda.raw.xz file and download it. It will usually be quite large, around 200-300 MB.
The disk image is compressed and partitioned, but usually we need an uncompressed, unpartitioned ("naked") filesystem. There are several ways to get this, but the easiest is:
$ unxz Fedora-Developer-Rawhide-xxxx.n.0-sda.raw.xz
$ guestfish -a Fedora-Developer-Rawhide-xxxx.n.0-sda.raw \
run : download /dev/sda1 Fedora-Developer-Rawhide-xxxx.n.0-sda1.raw
This creates a naked ext4 filesystem called *-sda1.raw which can be used in qemu or booted on the HiFive Unleashed board.
Root password
riscv
Boot under qemu
You will need a very recent version of qemu. If in doubt, compile from upstream qemu sources.
Get bbl from here or compile it from source.
qemu-system-riscv64 \
-nographic \
-machine virt \
-smp 4 \
-m 2G \
-kernel bbl \
-object rng-random,filename=/dev/urandom,id=rng0 \
-device virtio-rng-device,rng=rng0 \
-append "console=ttyS0 ro root=/dev/vda" \
-device virtio-blk-device,drive=hd0 \
-drive file=Fedora-Developer-Rawhide-xxxx.n.0-sda1.raw,format=raw,id=hd0 \
-device virtio-net-device,netdev=usernet \
-netdev user,id=usernet,hostfwd=tcp::10000-:22
Install on the HiFive Unleashed SD card
The naked ext4 filesystem can be copied over the second partition of the SD card.
You can also build a custom bbl+kernel+initramfs to boot directly into the SD card using these sources.
Install on the HiFive Unleashed using NBD server
Look at https://github.com/rwmjones/fedora-riscv-kernel in the sifive_u540 branch. This is quite complex to set up so it's best to ask on the #fedora-riscv IRC channel.