first successful boot!

.cargo/config.toml

@@ -0,0 +1,10 @@
+[unstable]
+json-target-spec = true
+build-std-features = ["compiler-builtins-mem"]
+build-std = ["core", "compiler_builtins"]
+
+[build]
+target = "x86_64-rusty_os.json"
+
+[target.'cfg(target_os = "none")']
+runner = "bootimage runner"

Cargo.lock

@@ -2,6 +2,15 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "bootloader"
+version = "0.9.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13f6a8a495d2f93fe3d6eb3a224f9aa749a63cfd746ed03eb5ddcbd00ade7d8f"
+
 [[package]]
 name = "rust-os-test"
 version = "0.1.0"
+dependencies = [
+ "bootloader",
+]

Cargo.toml

@@ -15,3 +15,4 @@ test=false
 bench=false
 
 [dependencies]
+bootloader = "0.9"

src/main.rs

@@ -3,10 +3,19 @@
 
 use core::panic::PanicInfo;
 
+static HELLO: &[u8] = b"Hello World";
+
 #[unsafe(no_mangle)] // dont mangle name of this function, keep as-is
 pub extern "C" fn _start() -> ! {
-    // this is entrypoint function
-    // linker looks for function named _start by default
+    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 {}
 }
 

x86_64-rusty_os.json

@@ -0,0 +1,16 @@
+{
+  "llvm-target": "x86_64-unknown-none",
+  "data-layout": "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128",
+  "arch": "x86_64",
+  "target-endian": "little",
+  "target-pointer-width": 64,
+  "target-c-int-width": 32,
+  "os": "none",
+  "executables": true,
+  "linker-flavor": "ld.lld",
+  "linker": "rust-lld",
+  "panic-strategy": "abort",
+  "disable-redzone": true,
+  "features": "-mmx,-sse,+soft-float",
+  "rustc-abi": "x86-softfloat"
+}