From b557dd62a456d71da837071e793aed68ee8676e3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alexander=20Neuh=C3=A4user?= <alexander.neuhaeuser@tuta.io>
Date: Sun, 18 May 2025 10:16:46 +0200
Subject: [PATCH] Hello World on simulator

---
 .cargo/config.toml       |  5 +++++
 .gitignore               |  1 +
 .vscode/launch.json      | 25 ++++++++++++++++++++++++
 .vscode/tasks.json       | 21 ++++++++++++++++++++
 Cargo.lock               |  7 +++++++
 Cargo.toml               | 11 +++++++++++
 link.ld                  | 19 ++++++++++++++++++
 rust-toolchain.toml      |  2 ++
 src/main.rs              | 42 ++++++++++++++++++++++++++++++++++++++++
 tools/start_simulator.sh |  3 +++
 10 files changed, 136 insertions(+)
 create mode 100644 .cargo/config.toml
 create mode 100644 .gitignore
 create mode 100644 .vscode/launch.json
 create mode 100644 .vscode/tasks.json
 create mode 100644 Cargo.lock
 create mode 100644 Cargo.toml
 create mode 100644 link.ld
 create mode 100644 rust-toolchain.toml
 create mode 100644 src/main.rs
 create mode 100755 tools/start_simulator.sh

diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 0000000..1c1fd15
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1,5 @@
+[build]
+target = "aarch64-unknown-none"
+
+[target.aarch64-unknown-none]
+rustflags = ["-C", "link-arg=-Tlink.ld"]
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/.vscode/launch.json b/.vscode/launch.json
new file mode 100644
index 0000000..36d3bf2
--- /dev/null
+++ b/.vscode/launch.json
@@ -0,0 +1,25 @@
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "Attach to QEMU (AArch64)",
+      "type": "cppdbg",
+      "request": "launch",
+      "program": "${workspaceFolder}/target/aarch64-unknown-none/debug/nova",
+      "miDebuggerServerAddress": "localhost:1234",
+      "miDebuggerPath": "gdb",
+      "cwd": "${workspaceFolder}",
+      "stopAtEntry": true,
+      "externalConsole": false,
+      "MIMode": "gdb",
+      "setupCommands": [
+        {
+          "description": "Enable pretty-printing for gdb",
+          "text": "-enable-pretty-printing",
+          "ignoreFailures": true
+        }
+      ],
+      "preLaunchTask": "Run QEMU"
+    }
+  ]
+}
diff --git a/.vscode/tasks.json b/.vscode/tasks.json
new file mode 100644
index 0000000..0cbd7f7
--- /dev/null
+++ b/.vscode/tasks.json
@@ -0,0 +1,21 @@
+{
+  "version": "2.0.0",
+  "tasks": [
+    {
+      "label": "Build",
+      "type": "shell",
+      "command": "cargo build --target aarch64-unknown-none",
+      "args": [],
+      "group": {
+        "kind": "build",
+        "isDefault": true
+      }
+    },
+    {
+      "label": "Run QEMU",
+      "type": "shell",
+      "command": "qemu-system-aarch64 -M raspi3b -cpu cortex-a72 -display none -kernel ${workspaceFolder}/target/aarch64-unknown-none/debug/nova -s -S",
+      "isBackground": true
+    }
+  ]
+}
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..8c89787
--- /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 = "nova"
+version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..45aea39
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "nova"
+version = "0.1.0"
+edition = "2021"
+
+
+[profile.dev]
+panic = "abort"
+
+[profile.release]
+panic = "abort"
diff --git a/link.ld b/link.ld
new file mode 100644
index 0000000..dfbf022
--- /dev/null
+++ b/link.ld
@@ -0,0 +1,19 @@
+SECTIONS
+{
+    . = 0x80000;     /* Kernel load address for AArch64 */
+    .text : { KEEP(*(.text.boot)) *(.text .text.* .gnu.linkonce.t*) }
+    .rodata : { *(.rodata .rodata.* .gnu.linkonce.r*) }
+    PROVIDE(_data = .);
+    .data : { *(.data .data.* .gnu.linkonce.d*) }
+    .bss (NOLOAD) : {
+        . = ALIGN(16);
+        __bss_start = .;
+        *(.bss .bss.*)
+        *(COMMON)
+        __bss_end = .;
+    }
+    _end = .;
+
+   /DISCARD/ : { *(.comment) *(.gnu*) *(.note*) *(.eh_frame*) }
+}
+__bss_size = (__bss_end - __bss_start)>>3;
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
new file mode 100644
index 0000000..5d56faf
--- /dev/null
+++ b/rust-toolchain.toml
@@ -0,0 +1,2 @@
+[toolchain]
+channel = "nightly"
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..d1a7d4e
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,42 @@
+#![no_main]
+#![no_std]
+#![feature(asm_experimental_arch)]
+
+use core::{
+    arch::asm,
+    fmt::{self, Write},
+    panic::PanicInfo,
+};
+
+#[panic_handler]
+fn panic(_panic: &PanicInfo) -> ! {
+    loop {}
+}
+
+const UART0_DR: u32 = 0x3F20_1000;
+
+struct Uart;
+
+impl Write for Uart {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for byte in s.bytes() {
+            unsafe {
+                core::ptr::write_volatile(UART0_DR as *mut u8, byte);
+            }
+        }
+        Ok(())
+    }
+}
+
+#[no_mangle]
+#[unsafe(naked)]
+pub extern "C" fn _start() -> ! {
+    core::arch::naked_asm!("mov sp, #0x80000", "bl main");
+}
+
+#[no_mangle]
+fn main() {
+    let mut uart = Uart {};
+    writeln!(uart, "Hello World!\n");
+    loop {}
+}
diff --git a/tools/start_simulator.sh b/tools/start_simulator.sh
new file mode 100755
index 0000000..353c915
--- /dev/null
+++ b/tools/start_simulator.sh
@@ -0,0 +1,3 @@
+cd "$(dirname "$0")"
+
+qemu-system-aarch64 -M raspi3b -cpu cortex-a53 -serial stdio -display none -kernel ../target/aarch64-unknown-none/debug/nova -s