Merge pull request #1436 from phil-opp/post-02-fix-target

Fix: `target-pointer-width` field now expects an integer

.cargo/config.toml

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

.github/workflows/code.yml

@@ -56,21 +56,16 @@ jobs:
         with:
           profile: minimal
           toolchain: nightly
+      - name: Install bootimage
+        run: cargo install bootimage --debug
       - name: Checkout Repository
         uses: actions/checkout@v2
-      - name: Add thumbv7em-none-eabihf Target
-        run: rustup target add thumbv7em-none-eabihf
-      - name: Build for thumbv7em-none-eabihf
-        run: cargo build --target thumbv7em-none-eabihf
-      - name: Build for Linux
-        if: runner.os == 'Linux'
-        run: cargo rustc -- -C link-arg=-nostartfiles
-      - name: Build for macOS
-        if: runner.os == 'macOS'
-        run: cargo rustc -- -C link-args="-e __start -static -nostartfiles"
-      - name: Build for Windows
-        if: runner.os == 'Windows'
-        run: cargo rustc -- -C link-args="/ENTRY:_start /SUBSYSTEM:console"
+      - name: Install Rustup Components
+        run: rustup component add rust-src llvm-tools-preview
+      - name: Run `cargo bootimage`
+        uses: actions-rs/cargo@v1
+        with:
+          command: bootimage
 
   check_formatting:
     name: Check Formatting

Cargo.lock

@@ -1,7 +1,16 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "blog_os"
 version = "0.1.0"
+dependencies = [
+ "bootloader",
+]
+
+[[package]]
+name = "bootloader"
+version = "0.9.33"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7bdfddac270bbdd45903296bc1caf29a7fdce6b326aaf0bbab7f04c5f98b7447"

Cargo.toml

@@ -2,12 +2,12 @@
 name = "blog_os"
 version = "0.1.0"
 authors = ["Philipp Oppermann <dev@phil-opp.com>"]
-edition = "2018"
+edition = "2024"
 
 [dependencies]
+bootloader = "0.9"
 
-[profile.dev]
-panic = "abort"
-
-[profile.release]
-panic = "abort"
+[[bin]]
+name = "blog_os"
+test = false
+bench = false

README.md

@@ -1,25 +1,61 @@
-# Blog OS (A Freestanding Rust Binary)
+# Blog OS (A Minimal Rust Kernel)
 
-[![Build Status](https://github.com/phil-opp/blog_os/workflows/Code/badge.svg?branch=post-01)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Code%22+branch%3Apost-01)
+[![Build Status](https://github.com/phil-opp/blog_os/workflows/Code/badge.svg?branch=post-02)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Code%22+branch%3Apost-02)
 
-This repository contains the source code for the [A Freestanding Rust Binary][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.
+This repository contains the source code for the [A Minimal Rust Kernel][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.
 
-[post]: https://os.phil-opp.com/freestanding-rust-binary/
+[post]: https://os.phil-opp.com/minimal-rust-kernel/
 
 **Check out the [master branch](https://github.com/phil-opp/blog_os) for more information.**
 
 ## Building
 
-To build the project on Linux, run:
+This project requires a nightly version of Rust because it uses some unstable features. At least nightly _2020-07-15_ is required for building. You might need to run `rustup update nightly --force` to update to the latest nightly even if some components such as `rustfmt` are missing it.
+
+You can build the project by running:
 
 ```
-cargo rustc -- -Clink-arg=-nostartfiles
+cargo build
 ```
 
-The entry point and the build command differ slightly on macOS and Windows. See the [post] for more information.
+To create a bootable disk image from the compiled kernel, you need to install the [`bootimage`] tool:
+
+[`bootimage`]: https://github.com/rust-osdev/bootimage
+
+```
+cargo install bootimage
+```
+
+After installing, you can create the bootable disk image by running:
+
+```
+cargo bootimage
+```
+
+This creates a bootable disk image in the `target/x86_64-blog_os/debug` directory.
 
 Please file an issue if you have any problems.
 
+## Running
+
+You can run the disk image in [QEMU] through:
+
+[QEMU]: https://www.qemu.org/
+
+```
+cargo run
+```
+
+[QEMU] and the [`bootimage`] tool need to be installed for this.
+
+You can also write the image to an USB stick for booting it on a real machine. On Linux, the command for this is:
+
+```
+dd if=target/x86_64-blog_os/debug/bootimage-blog_os.bin of=/dev/sdX && sync
+```
+
+Where `sdX` is the device name of your USB stick. **Be careful** to choose the correct device name, because everything on that device is overwritten.
+
 ## License
 
 Licensed under either of

rust-toolchain

@@ -0,0 +1 @@
+nightly

src/main.rs

@@ -3,8 +3,19 @@
 
 use core::panic::PanicInfo;
 
-#[no_mangle]
+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 {}
 }
 

x86_64-blog_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"
+  }