Annex is an experimental kernel developed for RISC-V in pure Rust (and a sprinkling of assembly). It's primary hardware target is the StarFive VisionFive 2, and has also been developed against QEMU.
This project requires several dependencies to run. Most importantly, you require a RISC-V toolchain. This project has been developed against SiFive's Freedom toolchain, available on their GitHub, https://github.com/sifive/freedom-tools.
Additionally, to emulate the kernel without running on real hardware, QEMU is required. Apt's version of QEMU is quite old, so it's better to build it yourself, see https://wiki.qemu.org/Hosts/Linux.
Finally, if you want to use U-Boot for running the kernel in QEMU, you will also need to clone and build a U-Boot binary. This requires U-Boot to be cross-compiled for RISC-V, so make sure you have the toolchain installed first.
CROSS_COMPILE=riscv64-linux-gnu- ARCH=riscv make qemu-riscv64_smode_defconfig
CROSS_COMPILE=riscv64-linux-gnu- ARCH=riscv make -j12 tools u-boot.bin
To run the kernel directly under OpenSBI in QEMU, run just qemu-raw. To run it under U-Boot, run just qemu-uboot.
To run the kernel on real hardware (presumably through U-Boot), run just uimage and either copy the resulting kernel.uimage to an SD card, or burn the kernel.img to the SD card directly.
You can see the full list of available commands through just -l.
In order to run the kernel through U-Boot, a uImage is provided. This uImage can be copied onto a USB or an SD card and then loaded and executed by U-Boot.
While these steps will be slightly hardware-specific, these are the steps to load it when using QEMU. This will load the kernel.uimage file from the virtio driver, and then boots it, while providing the address to the FDT. In standard Linux(?) form, this will execute the entrypoint so that the register a0 will contain the hart id, and a1 will contain the FDT address.
fatload virtio 0 0x84000000 kernel.uimagebootm 0x84000000 - ${fdtcontroladdr}
This can be configured in U-Boot as the default command, by setting CONFIG_BOOTCOMMAND to be these two steps.