From 02e6fa10eb67f6e3b0d3a1086c2ac17ce8e452d5 Mon Sep 17 00:00:00 2001
From: Mira Kristipati <akristip@cisco.com>
Date: Thu, 26 Jun 2025 23:27:08 -0400
Subject: [PATCH] initial commit

---
 .cargo/config.toml   |  5 +++++
 .gitignore           |  1 +
 Cargo.lock           |  7 +++++++
 Cargo.toml           |  6 ++++++
 arm-none-eabihf.json | 28 ++++++++++++++++++++++++++++
 notes.md             | 11 +++++++++++
 src/main.rs          | 26 ++++++++++++++++++++++++++
 7 files changed, 84 insertions(+)
 create mode 100644 .cargo/config.toml
 create mode 100644 .gitignore
 create mode 100644 Cargo.lock
 create mode 100644 Cargo.toml
 create mode 100644 arm-none-eabihf.json
 create mode 100644 notes.md
 create mode 100644 src/main.rs

diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 0000000..e5e3a73
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1,5 @@
+[build]
+target = "arm-none-eabihf.json"
+[unstable]
+build-std-features = ["compiler-builtins-mem"]
+build-std = ["core", "compiler_builtins"]
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..ce56bf4
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "jank_os"
+version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..522230f
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "jank_os"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
diff --git a/arm-none-eabihf.json b/arm-none-eabihf.json
new file mode 100644
index 0000000..24ce983
--- /dev/null
+++ b/arm-none-eabihf.json
@@ -0,0 +1,28 @@
+{
+  "llvm-target": "arm-none-eabihf",
+  "target-endian": "little",
+  "target-pointer-width": "32",
+  "target-c-int-width": "32",
+  "os": "none",
+  "env": "eabi",
+  "vendor": "unknown",
+  "arch": "arm",
+  "panic-strategy": "abort",
+  "llvm-floatabi": "hard",
+  "disable-redzone": true,
+  "linker-flavor": "gcc",
+  "linker": "arm-none-eabi-gcc",
+  "pre-link-args": {
+    "gcc": [
+      "-Wall",
+      "-nostdlib",
+      "-nostartfiles",
+      "-ffreestanding",
+      "-march=armv6"
+    ]
+  },
+  "features": "+strict-align,+v6,+vfp2,-d32",
+  "data-layout": "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64",
+  "executables": true,
+  "relocation-model": "static"
+}
diff --git a/notes.md b/notes.md
new file mode 100644
index 0000000..fc3b998
--- /dev/null
+++ b/notes.md
@@ -0,0 +1,11 @@
+build: `cargo build --target arm-none-eabihf.json -Z build-std=core,compiler_builtins`
+
+qemu: `qemu-system-arm -m 256 -M raspi0 -serial stdio -kernel kernel.elf`
+
+---
+
+# References
+
+- https://os.phil-opp.com/minimal-rust-kernel/
+- https://wiki.osdev.org/Raspberry_Pi_Bare_Bones
+- https://wiki.osdev.org/Raspberry_Pi_Bare_Bones_Rust
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..4f5268c
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,26 @@
+#![no_std]
+#![no_main]
+
+use core::panic::PanicInfo;
+
+/// This function is called on panic.
+#[panic_handler]
+fn panic(_info: &PanicInfo) -> ! {
+    loop {}
+}
+
+static HELLO: &[u8] = b"Hello World!";
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+    let vga_buffer = 0xb8000 as *mut u8;
+
+    for (i, &byte) in HELLO.iter().enumerate() {
+        unsafe {
+            *vga_buffer.offset(i as isize * 2) = byte;
+            *vga_buffer.offset(i as isize * 2 + 1) = 0xb;
+        }
+    }
+
+    loop {}
+}