Native Unikraft Microkernel Build for Zig libraries
===================================================


Building
--------

Everything assumes Linux on x86_64, though some trivial changes should allow
aarch64. Install the following:

* [Zig](https://ziglang.org). Versions 0.12.0 and 0.13.0 should work
* [QEMU](https://www.qemu.org/download/#linux)
* [Kraftkit](https://unikraft.org/docs/cli/install)

Then run `zig build run` and everything will compile and run. The zig source
code is all in the `ziggy` directory. This is all prototype level code at this
point.

undefined.c
-----------

This file aims to fill in all the undefined symbols that are referenced when
a zig project links libC (necessary for unikraft kernel development). However,
this is very incomplete. The `.config.hellowworld_qemu-x86_64` file, usually
managed by the invocation of the TUI started by `kraft menu`, will add/remove
features that result in various libc symbols being implemented. A few
`#ifdef` statements exist currently, but even the few that are in there aren't
quite right...this file is mostly a "hack around until it works" effort.

Knowing that this is an initial effort, care was put into making sure that
when a symbol is actually **used** at runtime, the unikernel will crash after
posting a message indicating the specific function call that was involved. This
is designed to either a) correct the configuration using `kraft menu` or
b) provide an implementation directly in `undefined.c`. In some cases, I prefer
the implementation in `undefined.c`, most specifically the `write` function,
which will output stderr messages in red.

Notes
-----


The build script basically runs these commands:

```sh
(cd ziggy && zig build)
LIBZIGGY=$(pwd)/ziggy/zig-out/lib/libziggy.a kraft build --plat qemu --arch x86_64 --log-level debug --log-type basic
kraft run --plat qemu --arch x86_64
```