Post 2 - A minimal kernel

.cargo/config.toml

@@ -0,0 +1,9 @@
+[unstable]
+build-std-features = ["compiler-builtins-mem"]
+build-std = ["core", "compiler_builtins"]
+
+[build]
+target = "x86_64-blog_os.json"
+
+[target.'cfg(target_os = "none")']
+runner = "bootimage runner"

blog_os/Cargo.toml

@@ -6,9 +6,4 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-
-[profile.dev]
-panic = "abort"
-
-[profile.release]
-panic = "abort"
+bootloader = "0.9"

blog_os/src/main.rs

@@ -1,12 +1,21 @@
-#![no_std] // don't link the Rust standard library
-#![no_main] // disable all Rust-level entry points
+#![no_std]
+#![no_main]
 
 use core::panic::PanicInfo;
 
-#[no_mangle] // don't mangle the name of this function
+static HELLO: &[u8] = b"Hello World!";
+
+#[no_mangle]
 pub extern "C" fn _start() -> ! {
-    // this function is the entry point, since the linker looks for a 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 {}
 }
 
@@ -14,4 +23,4 @@ pub extern "C" fn _start() -> ! {
 #[panic_handler]
 fn panic(_info: &PanicInfo) -> ! {
     loop {}
-}
+}

x86_64-blog_os.json

@@ -0,0 +1,15 @@
+{
+    "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"
+}