Initial code for second edition

Cargo.toml

@@ -4,3 +4,11 @@ name = "blog_os"
 version = "0.2.0"
 
 [dependencies]
+
+# the profile used for `cargo build`
+[profile.dev]
+panic = "abort" # disable stack unwinding on panic
+
+# the profile used for `cargo build --release`
+[profile.release]
+panic = "abort" # disable stack unwinding on panic

src/main.rs

@@ -0,0 +1,27 @@
+#![feature(lang_items)] // required for defining the panic handler
+#![no_std] // don't link the Rust standard library
+#![no_main] // disable all Rust-level entry points
+
+#[no_mangle] // don't mangle the name of this function
+pub fn _start() -> ! {
+    // this function is the entry point, since the linker looks for a function
+    // named `_start_` by default
+    let vga_buffer = 0xb8000 as *const u8 as *mut u8;
+    unsafe {
+        *vga_buffer.offset(0) = b'O';
+        *vga_buffer.offset(1) = 0xa; // foreground color green
+        *vga_buffer.offset(0) = b'K';
+        *vga_buffer.offset(3) = 0xa; // foreground color green
+    }
+
+    loop {}
+}
+
+#[lang = "panic_fmt"] // define a function that should be called on panic
+#[no_mangle] // TODO required?
+pub extern fn rust_begin_panic(_msg: core::fmt::Arguments,
+                               _file: &'static str,
+                               _line: u32,
+                               _column: u32) -> ! {
+    loop {}
+}