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https://github.com/kivikakk/daintree

[non-functional] ARMv8-A/RISC-V kernel (with UEFI bootloader)
https://github.com/kivikakk/daintree

armv8 kernel risc-v uefi zig

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[non-functional] ARMv8-A/RISC-V kernel (with UEFI bootloader)

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# daintree 



An operating system plus a UEFI bootloader, all written in Zig. Currently targetting and testing on:



- QEMU (arm64 + riscv64) with U-Boot

  - The U-Boot build is included in the repository, and is based on

    [patch series adding QFW and QEMU ramfb support on Arm](https://git.src.kameliya.ee/~kameliya/u-boot/log/qfw-ramfb).

    I'm hoping to land this in the coming weeks.

  - There's the [same for riscv](https://git.src.kameliya.ee/~kameliya/u-boot/log/qfw-ramfb-riscv).

  - CI runs on QEMU and currently makes sure the target can boot and be powered off by command at the serial console. (samples: [arm64](https://buildkite.com/daintree/daintree-arm64/builds/150#a0a1da6d-3764-4529-b25f-66cc605080c7/27-151), [riscv64](https://buildkite.com/daintree/daintree-riscv64/builds/50#38096c20-6e7c-4712-b7dc-7f56ccc9cffe/27-166))

- ROCKPro64 (arm64) with U-Boot

  - A mainline build is okay, but it must contain this

    [EFI loader fix](https://source.denx.de/u-boot/u-boot/-/commit/9d30a941cce5ed055da18398f4deba18830d00d6).

    At time of writing it has not been included in any release.



Planned support for:



- HiFive Unmatched with U-Boot



There's a little [dev blog](https://github.com/kivikakk/daintree/discussions/1)

I hope to maintain as I go.  See also [my personal blog](https://kivikakk.ee):



- 2021-02-28: [Knowing when to look past your code](https://kivikakk.ee/2021/02/28/loader/)

- 2021-02-13: [DTB parser implementing notes](https://kivikakk.ee/2021/02/13/dtb-parser-implementing-notes/)



## dainboot



A gentle introduction to Zig's UEFI support. Boots like this:



- Checks loaded image options.

  - You can pass `kernel 0x12345678 0x1234` to give it the location of the

    kernel already loaded in RAM. Useful for TFTP boot, which itself is handy

    for faster development cycles on bare metal.

  - You may also pass `dtb 0x12345678 0x1234` to give information about a

    DTB/FDT (device tree blob/flattened device tree) already in memory.

  - Separate successive options with spaces, i.e. `kernel   dtb

     `.

- If DTB wasn't loaded from memory, checks to see if one was passed in via

  UEFI.

- If kernel or DTB (or both) were not loaded from memory, scans filesystems the

  UEFI system knows about, looking in the root directories for files named

  `dainkrnl` and `dtb`.

- Picks the biggest unused slab of conventional memory and places the kernel

  there.

- Clears data and instruction caches for loaded memory.

- Parses the DTB and attempts to locate the serial UART port.

- Exits UEFI boot services.

- If necessary, disables a whole lot of traps and goes to EL1.

- Jumps to the kernel, passing the memory map, UART write port, and framebuffer

  prepared by UEFI.



![](doc/img/dainboot-qemu.png)



![](doc/img/dainboot-rockpro64.jpg)



## dainkrnl



- Uses the UART write port to debug before the MMU is enabled.

- Sets up the MMU, mapping the kernel, stack, framebuffer, DTB, UART device,

  etc. into high addresses.

- Parses the DTB to understand what kind of serial device is connected and how

  to access

  [PSCI](https://developer.arm.com/architectures/system-architectures/software-standards/psci).

- Implements a console using a classic VGA font.

- A shell lets you reset or poweroff the system.  You can only use serial for

  input, but the output is muxed to the framebuffer if one is available.



![](doc/img/dainkrnl-charset-qemu.png)



![](doc/img/dainkrnl-charset-rockpro64.jpg)



![](doc/img/dainkrnl-shell-qemu.png)



## license



MIT.



Some included binaries are GPL-2+ or GPL-2.0+ -- copyright notices retained and

sources noted where so.



The [`roms/`](roms/) directory contains an arm64 build of

[U-Boot](http://www.denx.de/wiki/U-Boot/WebHome), (C) Wolfgang Denk and

licensed under GPL 2.  See [U-Boot's Licensing

page](https://www.denx.de/wiki/U-Boot/Licensing)

for details.  The source can be found at

.



It also contains a riscv64 build of same at

.  It is

embedded in a build of [OpenSBI](https://github.com/riscv/opensbi), (C) 2019

Western Digital Corporation, licensed under BSD-2-Clause.