Update to bootloader-locator 0.0.3; cargo fmt; add QEMU run args

Create a testable trait for printing test messages automatically

.cargo/config.toml

@@ -1,9 +1,11 @@
 [unstable]
-build-std = ["core", "compiler_builtins"]
+# build-std = ["core", "compiler_builtins"]
-build-std-features = ["compiler-builtins-mem"]
 
 [build]
-target = "x86_64-blog_os.json"
+# target = "x86_64-blog_os.json"
 
 [target.'cfg(target_os = "none")']
-runner = "bootimage runner"
+runner = "cargo run --manifest-path disk_image/Cargo.toml --bin runner --quiet"
+
+[alias]
+bootimage = "run --manifest-path disk_image/Cargo.toml --bin disk_image --quiet"

.github/workflows/build-code.yml

@@ -1,4 +1,4 @@
-name: Code
+name: Build Code
 
 on:
   push:
@@ -16,7 +16,6 @@ jobs:
   check:
     name: Check
     strategy:
-      fail-fast: false
       matrix:
         platform: [
           ubuntu-latest,
@@ -42,7 +41,6 @@ jobs:
   test:
     name: Test
     strategy:
-      fail-fast: false
       matrix:
         platform: [
           ubuntu-latest,
@@ -67,6 +65,35 @@ jobs:
         with:
           command: bootimage
 
+      # install QEMU
+      - name: Install QEMU (Linux)
+        run: sudo apt update && sudo apt install qemu-system-x86
+        if: runner.os == 'Linux'
+      - name: Install QEMU (macOS)
+        run: brew install qemu
+        if: runner.os == 'macOS'
+        env:
+          HOMEBREW_NO_AUTO_UPDATE: 1
+          HOMEBREW_NO_BOTTLE_SOURCE_FALLBACK: 1
+          HOMEBREW_NO_INSTALL_CLEANUP: 1
+      - name: Install Scoop (Windows)
+        run: |
+          Invoke-Expression (New-Object System.Net.WebClient).DownloadString('https://get.scoop.sh')
+          echo ::add-path::$HOME\scoop\shims
+        if: runner.os == 'Windows'
+        shell: pwsh
+      - name: Install QEMU (Windows)
+        run: scoop install qemu
+        if: runner.os == 'Windows'
+        shell: pwsh
+      - name: "Print QEMU Version"
+        run: qemu-system-x86_64 --version
+
+      - name: Run `cargo test`
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+
   check_formatting:
     name: Check Formatting
     runs-on: ubuntu-latest

Cargo.lock

@@ -1,16 +1,266 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 4
+[[package]]
+name = "anyhow"
+version = "1.0.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6b602bfe940d21c130f3895acd65221e8a61270debe89d628b9cb4e3ccb8569b"
+
+[[package]]
+name = "bit_field"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ed8765909f9009617974ab6b7d332625b320b33c326b1e9321382ef1999b5d56"
+
+[[package]]
+name = "bitflags"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 
 [[package]]
 name = "blog_os"
 version = "0.1.0"
 dependencies = [
  "bootloader",
+ "lazy_static",
+ "rlibc",
+ "spin",
+ "uart_16550",
+ "volatile",
+ "x86_64",
 ]
 
 [[package]]
 name = "bootloader"
-version = "0.9.32"
+version = "0.9.8"
+
+[[package]]
+name = "bootloader-locator"
+version = "0.0.3"
+dependencies = [
+ "cargo_metadata",
+ "locate-cargo-manifest",
+ "thiserror",
+]
+
+[[package]]
+name = "cargo_metadata"
+version = "0.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ea119c3ed05625c179e09d17d0914570a3753ca09c890a73d98f6b72aea00d2"
+checksum = "89fec17b16f1ac67908af82e47d0a90a7afd0e1827b181cd77504323d3263d35"
+dependencies = [
+ "semver",
+ "serde",
+ "serde_json",
+]
+
+[[package]]
+name = "disk_image"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "bootloader-locator",
+ "locate-cargo-manifest",
+ "runner-utils",
+]
+
+[[package]]
+name = "itoa"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc6f3ad7b9d11a0c00842ff8de1b60ee58661048eb8049ed33c73594f359d7e6"
+
+[[package]]
+name = "json"
+version = "0.12.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "078e285eafdfb6c4b434e0d31e8cfcb5115b651496faca5749b88fafd4f23bfd"
+
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+dependencies = [
+ "spin",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.76"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "755456fae044e6fa1ebbbd1b3e902ae19e73097ed4ed87bb79934a867c007bc3"
+
+[[package]]
+name = "locate-cargo-manifest"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d264d672563b20c0a2eb9045f4072e1352002f6c316cc0677bed8b767e17b7e1"
+dependencies = [
+ "json",
+ "thiserror",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "04f5f085b5d71e2188cb8271e5da0161ad52c3f227a661a3c135fdf28e258b12"
+dependencies = [
+ "unicode-xid",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa563d17ecb180e500da1cfd2b028310ac758de548efdd203e18f283af693f37"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "rlibc"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc874b127765f014d792f16763a81245ab80500e2ad921ed4ee9e82481ee08fe"
+
+[[package]]
+name = "runner-utils"
+version = "0.0.2"
+dependencies = [
+ "thiserror",
+ "wait-timeout",
+]
+
+[[package]]
+name = "ryu"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "71d301d4193d031abdd79ff7e3dd721168a9572ef3fe51a1517aba235bd8f86e"
+
+[[package]]
+name = "semver"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "394cec28fa623e00903caf7ba4fa6fb9a0e260280bb8cdbbba029611108a0190"
+dependencies = [
+ "semver-parser",
+ "serde",
+]
+
+[[package]]
+name = "semver-parser"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
+
+[[package]]
+name = "serde"
+version = "1.0.115"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e54c9a88f2da7238af84b5101443f0c0d0a3bbdc455e34a5c9497b1903ed55d5"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.115"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "609feed1d0a73cc36a0182a840a9b37b4a82f0b1150369f0536a9e3f2a31dc48"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "serde_json"
+version = "1.0.57"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "164eacbdb13512ec2745fb09d51fd5b22b0d65ed294a1dcf7285a360c80a675c"
+dependencies = [
+ "itoa",
+ "ryu",
+ "serde",
+]
+
+[[package]]
+name = "spin"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e63cff320ae2c57904679ba7cb63280a3dc4613885beafb148ee7bf9aa9042d"
+
+[[package]]
+name = "syn"
+version = "1.0.39"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "891d8d6567fe7c7f8835a3a98af4208f3846fba258c1bc3c31d6e506239f11f9"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-xid",
+]
+
+[[package]]
+name = "thiserror"
+version = "1.0.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7dfdd070ccd8ccb78f4ad66bf1982dc37f620ef696c6b5028fe2ed83dd3d0d08"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bd80fc12f73063ac132ac92aceea36734f04a1d93c1240c6944e23a3b8841793"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "uart_16550"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e58fc40dc1712664fc9b0a7bd8ca2f21ab49960924fb245a80a05e1e92f3dfe9"
+dependencies = [
+ "bitflags",
+ "x86_64",
+]
+
+[[package]]
+name = "unicode-xid"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7fe0bb3479651439c9112f72b6c505038574c9fbb575ed1bf3b797fa39dd564"
+
+[[package]]
+name = "volatile"
+version = "0.4.0-alpha.00"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a1da81878b88e2b57ca8b3d62c0c3e9979d9531cfe0e6d1c094174d8458eac6"
+
+[[package]]
+name = "wait-timeout"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f200f5b12eb75f8c1ed65abd4b2db8a6e1b138a20de009dacee265a2498f3f6"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "x86_64"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "365de37eb7c6da582cbb510dd0f3f1235d24ff6309a8a96e8a9909cc9bfd608f"
+dependencies = [
+ "bit_field",
+ "bitflags",
+]

Cargo.toml

@@ -2,12 +2,33 @@
 name = "blog_os"
 version = "0.1.0"
 authors = ["Philipp Oppermann <dev@phil-opp.com>"]
-edition = "2024"
+edition = "2018"
+
+[workspace]
+members = [
+    "disk_image",
+]
+
+[[test]]
+name = "should_panic"
+harness = false
 
 [dependencies]
-bootloader = "0.9"
+bootloader = { path = "../../uefi-test"}
+rlibc = "1.0.0"
+volatile = "0.4.0-alpha"
+spin = "0.5.2"
+x86_64 = "0.11.0"
+uart_16550 = "0.2.0"
 
-[[bin]]
+[dependencies.lazy_static]
-name = "blog_os"
+version = "1.0"
-test = false
+features = ["spin_no_std"]
-bench = false
+
+
+[package.metadata.bootimage]
+test-args = [
+    "-device", "isa-debug-exit,iobase=0xf4,iosize=0x04", "-serial", "stdio",
+    "-display", "none"
+]
+test-success-exit-code = 33         # (0x10 << 1) | 1

README.md

@@ -1,10 +1,10 @@
-# Blog OS (A Minimal Rust Kernel)
+# Blog OS (Testing)
 
-[![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)
+[![Build Status](https://github.com/phil-opp/blog_os/workflows/Build%20Code/badge.svg?branch=post-04)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Build+Code%22+branch%3Apost-04)
 
-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.
+This repository contains the source code for the [Testing][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.
 
-[post]: https://os.phil-opp.com/minimal-rust-kernel/
+[post]: https://os.phil-opp.com/testing/
 
 **Check out the [master branch](https://github.com/phil-opp/blog_os) for more information.**
 
@@ -56,6 +56,10 @@ 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.
 
+## Testing
+
+To run the unit and integration tests, execute `cargo xtest`.
+
 ## License
 
 Licensed under either of

disk_image/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "disk_image"
+version = "0.1.0"
+authors = ["Philipp Oppermann <dev@phil-opp.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+anyhow = "1.0.32"
+bootloader-locator = {path = "../../../bootloader-locator"}
+runner-utils = { path = "../../../runner-utils/" }
+locate-cargo-manifest = "0.2.0"

disk_image/src/bin/runner.rs

@@ -0,0 +1,57 @@
+use anyhow::anyhow;
+use std::{
+    path::PathBuf,
+    process::{Command, ExitStatus},
+    time::Duration,
+};
+
+const RUN_ARGS: &[&str] = &["-d", "int", "--no-reboot", "-s"];
+const TEST_ARGS: &[&str] = &[
+    "-device",
+    "isa-debug-exit,iobase=0xf4,iosize=0x04",
+    "-serial",
+    "stdio",
+    "-display",
+    "none",
+    "--no-reboot",
+];
+const TEST_TIMEOUT_SECS: u64 = 10;
+
+fn main() -> anyhow::Result<()> {
+    let kernel_binary_path = {
+        let path = PathBuf::from(std::env::args().nth(1).unwrap());
+        path.canonicalize()?
+    };
+
+    let disk_image = disk_image::create_disk_image(&kernel_binary_path, true)?;
+
+    let mut run_cmd = Command::new("qemu-system-x86_64");
+    run_cmd
+        .arg("-drive")
+        .arg(format!("format=raw,file={}", disk_image.display()));
+
+    let binary_kind = runner_utils::binary_kind(&kernel_binary_path);
+    if binary_kind.is_test() {
+        run_cmd.args(TEST_ARGS);
+
+        let exit_status = run_test_command(run_cmd)?;
+        match exit_status.code() {
+            Some(33) => {} // success
+            other => return Err(anyhow!("Test failed (exit code: {:?})", other)),
+        }
+    } else {
+        run_cmd.args(RUN_ARGS);
+
+        let exit_status = run_cmd.status()?;
+        if !exit_status.success() {
+            std::process::exit(exit_status.code().unwrap_or(1));
+        }
+    }
+
+    Ok(())
+}
+
+fn run_test_command(mut cmd: Command) -> anyhow::Result<ExitStatus> {
+    let status = runner_utils::run_with_timeout(&mut cmd, Duration::from_secs(TEST_TIMEOUT_SECS))?;
+    Ok(status)
+}

disk_image/src/lib.rs

@@ -0,0 +1,45 @@
+use anyhow::anyhow;
+use std::{
+    path::{Path, PathBuf},
+    process::Command,
+};
+
+pub fn create_disk_image(kernel_binary_path: &Path, bios_only: bool) -> anyhow::Result<PathBuf> {
+    let bootloader_info = bootloader_locator::locate_bootloader()?;
+    let kernel_manifest_path = &bootloader_info.kernel_manifest_path;
+
+    let mut build_cmd = Command::new(env!("CARGO"));
+    build_cmd.current_dir(bootloader_info.package.manifest_path.parent().unwrap());
+    build_cmd.arg("builder");
+    build_cmd
+        .arg("--kernel-manifest")
+        .arg(&kernel_manifest_path);
+    build_cmd.arg("--kernel-binary").arg(&kernel_binary_path);
+    build_cmd
+        .arg("--target-dir")
+        .arg(kernel_manifest_path.parent().unwrap().join("target"));
+    build_cmd
+        .arg("--out-dir")
+        .arg(kernel_binary_path.parent().unwrap());
+    build_cmd.arg("--quiet");
+    if bios_only {
+        build_cmd.arg("--firmware").arg("bios");
+    }
+
+    if !build_cmd.status()?.success() {
+        return Err(anyhow!("build failed"));
+    }
+
+    let kernel_binary_name = kernel_binary_path.file_name().unwrap().to_str().unwrap();
+    let disk_image = kernel_binary_path
+        .parent()
+        .unwrap()
+        .join(format!("bootimage-bios-{}.bin", kernel_binary_name));
+    if !disk_image.exists() {
+        return Err(anyhow!(
+            "Disk image does not exist at {} after bootloader build",
+            disk_image.display()
+        ));
+    }
+    Ok(disk_image)
+}

disk_image/src/main.rs

@@ -0,0 +1,40 @@
+use anyhow::anyhow;
+use std::process::Command;
+
+const TARGET_NAME: &str = "x86_64-blog_os";
+const KERNEL_BINARIES: &[&str] = &["blog_os"];
+
+fn main() -> anyhow::Result<()> {
+    // build all binaries
+    let mut build_cmd = Command::new(env!("CARGO"));
+    build_cmd.arg("build");
+    build_cmd.arg("--release");
+    build_cmd.arg("-Zbuild-std=core");
+    build_cmd
+        .arg("--target")
+        .arg(format!("{}.json", TARGET_NAME));
+    if !build_cmd.status()?.success() {
+        return Err(anyhow!("build failed"));
+    };
+
+    let kernel_manifest = locate_cargo_manifest::locate_manifest()?;
+    let target_dir_root = kernel_manifest.parent().unwrap().join("target");
+    let target_dir = target_dir_root.join(TARGET_NAME).join("release");
+
+    for binary_name in KERNEL_BINARIES {
+        let binary_path = {
+            let path = target_dir.join(binary_name);
+            path.canonicalize()?
+        };
+
+        let disk_image = disk_image::create_disk_image(&binary_path, false)?;
+
+        println!(
+            "Created disk image for binary {} at {}",
+            binary_name,
+            disk_image.display()
+        );
+    }
+
+    Ok(())
+}

src/lib.rs

@@ -0,0 +1,72 @@
+#![no_std]
+#![cfg_attr(test, no_main)]
+#![feature(custom_test_frameworks)]
+#![test_runner(crate::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+extern crate rlibc;
+
+use core::panic::PanicInfo;
+
+pub mod serial;
+//pub mod vga_buffer;
+
+pub trait Testable {
+    fn run(&self) -> ();
+}
+
+impl<T> Testable for T
+where
+    T: Fn(),
+{
+    fn run(&self) {
+        serial_print!("{}...\t", core::any::type_name::<T>());
+        self();
+        serial_println!("[ok]");
+    }
+}
+
+pub fn test_runner(tests: &[&dyn Testable]) {
+    serial_println!("Running {} tests", tests.len());
+    for test in tests {
+        test.run();
+    }
+    exit_qemu(QemuExitCode::Success);
+}
+
+pub fn test_panic_handler(info: &PanicInfo) -> ! {
+    serial_println!("[failed]\n");
+    serial_println!("Error: {}\n", info);
+    exit_qemu(QemuExitCode::Failed);
+    loop {}
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(u32)]
+pub enum QemuExitCode {
+    Success = 0x10,
+    Failed = 0x11,
+}
+
+pub fn exit_qemu(exit_code: QemuExitCode) {
+    use x86_64::instructions::port::Port;
+
+    unsafe {
+        let mut port = Port::new(0xf4);
+        port.write(exit_code as u32);
+    }
+}
+
+/// Entry point for `cargo xtest`
+#[cfg(test)]
+#[no_mangle]
+pub extern "C" fn _start() -> ! {
+    test_main();
+    loop {}
+}
+
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    test_panic_handler(info)
+}

src/main.rs

@@ -1,26 +1,49 @@
 #![no_std]
 #![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(blog_os::test_runner)]
+#![reexport_test_harness_main = "test_main"]
 
-use core::panic::PanicInfo;
+use blog_os::serial_println;
+use core::{panic::PanicInfo, ptr, slice};
 
-static HELLO: &[u8] = b"Hello World!";
+#[no_mangle]
+pub extern "C" fn _start(boot_info: &'static mut bootloader::boot_info::BootInfo) -> ! {
+    #[cfg(test)]
+    test_main();
 
-#[unsafe(no_mangle)]
+    let mut framebuffer = {
-pub extern "C" fn _start() -> ! {
+        let ptr = boot_info.framebuffer.start_addr as *mut u8;
-    let vga_buffer = 0xb8000 as *mut u8;
+        let slice = unsafe { slice::from_raw_parts_mut(ptr, boot_info.framebuffer.len) };
+        volatile::Volatile::new(slice)
+    };
 
-    for (i, &byte) in HELLO.iter().enumerate() {
+    //serial_println!("Hello World{}", "!");
-        unsafe {
+
-            *vga_buffer.offset(i as isize * 2) = byte;
+    for i in 0..boot_info.framebuffer.len {
-            *vga_buffer.offset(i as isize * 2 + 1) = 0xb;
+        framebuffer.index_mut(i).write(0x99);
-        }
     }
 
-    loop {}
+    loop {
+        x86_64::instructions::hlt();
+    }
 }
 
 /// This function is called on panic.
+#[cfg(not(test))]
 #[panic_handler]
-fn panic(_info: &PanicInfo) -> ! {
+fn panic(info: &PanicInfo) -> ! {
+    serial_println!("{}", info);
     loop {}
 }
+
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    blog_os::test_panic_handler(info)
+}
+
+#[test_case]
+fn trivial_assertion() {
+    assert_eq!(1, 1);
+}

src/serial.rs

@@ -0,0 +1,37 @@
+use lazy_static::lazy_static;
+use spin::Mutex;
+use uart_16550::SerialPort;
+
+lazy_static! {
+    pub static ref SERIAL1: Mutex<SerialPort> = {
+        let mut serial_port = unsafe { SerialPort::new(0x3F8) };
+        serial_port.init();
+        Mutex::new(serial_port)
+    };
+}
+
+#[doc(hidden)]
+pub fn _print(args: ::core::fmt::Arguments) {
+    use core::fmt::Write;
+    SERIAL1
+        .lock()
+        .write_fmt(args)
+        .expect("Printing to serial failed");
+}
+
+/// Prints to the host through the serial interface.
+#[macro_export]
+macro_rules! serial_print {
+    ($($arg:tt)*) => {
+        $crate::serial::_print(format_args!($($arg)*));
+    };
+}
+
+/// Prints to the host through the serial interface, appending a newline.
+#[macro_export]
+macro_rules! serial_println {
+    () => ($crate::serial_print!("\n"));
+    ($fmt:expr) => ($crate::serial_print!(concat!($fmt, "\n")));
+    ($fmt:expr, $($arg:tt)*) => ($crate::serial_print!(
+        concat!($fmt, "\n"), $($arg)*));
+}

src/vga_buffer.rs

@@ -0,0 +1,193 @@
+use core::fmt;
+use lazy_static::lazy_static;
+use spin::Mutex;
+use volatile::Volatile;
+
+lazy_static! {
+    /// A global `Writer` instance that can be used for printing to the VGA text buffer.
+    ///
+    /// Used by the `print!` and `println!` macros.
+    pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
+        column_position: 0,
+        color_code: ColorCode::new(Color::Yellow, Color::Black),
+        buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
+    });
+}
+
+/// The standard color palette in VGA text mode.
+#[allow(dead_code)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(u8)]
+pub enum Color {
+    Black = 0,
+    Blue = 1,
+    Green = 2,
+    Cyan = 3,
+    Red = 4,
+    Magenta = 5,
+    Brown = 6,
+    LightGray = 7,
+    DarkGray = 8,
+    LightBlue = 9,
+    LightGreen = 10,
+    LightCyan = 11,
+    LightRed = 12,
+    Pink = 13,
+    Yellow = 14,
+    White = 15,
+}
+
+/// A combination of a foreground and a background color.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(transparent)]
+struct ColorCode(u8);
+
+impl ColorCode {
+    /// Create a new `ColorCode` with the given foreground and background colors.
+    fn new(foreground: Color, background: Color) -> ColorCode {
+        ColorCode((background as u8) << 4 | (foreground as u8))
+    }
+}
+
+/// A screen character in the VGA text buffer, consisting of an ASCII character and a `ColorCode`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(C)]
+struct ScreenChar {
+    ascii_character: u8,
+    color_code: ColorCode,
+}
+
+/// The height of the text buffer (normally 25 lines).
+const BUFFER_HEIGHT: usize = 25;
+/// The width of the text buffer (normally 80 columns).
+const BUFFER_WIDTH: usize = 80;
+
+/// A structure representing the VGA text buffer.
+#[repr(transparent)]
+struct Buffer {
+    chars: [[Volatile<ScreenChar>; BUFFER_WIDTH]; BUFFER_HEIGHT],
+}
+
+/// A writer type that allows writing ASCII bytes and strings to an underlying `Buffer`.
+///
+/// Wraps lines at `BUFFER_WIDTH`. Supports newline characters and implements the
+/// `core::fmt::Write` trait.
+pub struct Writer {
+    column_position: usize,
+    color_code: ColorCode,
+    buffer: &'static mut Buffer,
+}
+
+impl Writer {
+    /// Writes an ASCII byte to the buffer.
+    ///
+    /// Wraps lines at `BUFFER_WIDTH`. Supports the `\n` newline character.
+    pub fn write_byte(&mut self, byte: u8) {
+        match byte {
+            b'\n' => self.new_line(),
+            byte => {
+                if self.column_position >= BUFFER_WIDTH {
+                    self.new_line();
+                }
+
+                let row = BUFFER_HEIGHT - 1;
+                let col = self.column_position;
+
+                let color_code = self.color_code;
+                self.buffer.chars[row][col].write(ScreenChar {
+                    ascii_character: byte,
+                    color_code,
+                });
+                self.column_position += 1;
+            }
+        }
+    }
+
+    /// Writes the given ASCII string to the buffer.
+    ///
+    /// Wraps lines at `BUFFER_WIDTH`. Supports the `\n` newline character. Does **not**
+    /// support strings with non-ASCII characters, since they can't be printed in the VGA text
+    /// mode.
+    fn write_string(&mut self, s: &str) {
+        for byte in s.bytes() {
+            match byte {
+                // printable ASCII byte or newline
+                0x20..=0x7e | b'\n' => self.write_byte(byte),
+                // not part of printable ASCII range
+                _ => self.write_byte(0xfe),
+            }
+        }
+    }
+
+    /// Shifts all lines one line up and clears the last row.
+    fn new_line(&mut self) {
+        for row in 1..BUFFER_HEIGHT {
+            for col in 0..BUFFER_WIDTH {
+                let character = self.buffer.chars[row][col].read();
+                self.buffer.chars[row - 1][col].write(character);
+            }
+        }
+        self.clear_row(BUFFER_HEIGHT - 1);
+        self.column_position = 0;
+    }
+
+    /// Clears a row by overwriting it with blank characters.
+    fn clear_row(&mut self, row: usize) {
+        let blank = ScreenChar {
+            ascii_character: b' ',
+            color_code: self.color_code,
+        };
+        for col in 0..BUFFER_WIDTH {
+            self.buffer.chars[row][col].write(blank);
+        }
+    }
+}
+
+impl fmt::Write for Writer {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.write_string(s);
+        Ok(())
+    }
+}
+
+/// Like the `print!` macro in the standard library, but prints to the VGA text buffer.
+#[macro_export]
+macro_rules! print {
+    ($($arg:tt)*) => ($crate::vga_buffer::_print(format_args!($($arg)*)));
+}
+
+/// Like the `println!` macro in the standard library, but prints to the VGA text buffer.
+#[macro_export]
+macro_rules! println {
+    () => ($crate::print!("\n"));
+    ($($arg:tt)*) => ($crate::print!("{}\n", format_args!($($arg)*)));
+}
+
+/// Prints the given formatted string to the VGA text buffer through the global `WRITER` instance.
+#[doc(hidden)]
+pub fn _print(args: fmt::Arguments) {
+    use core::fmt::Write;
+    WRITER.lock().write_fmt(args).unwrap();
+}
+
+#[test_case]
+fn test_println_simple() {
+    println!("test_println_simple output");
+}
+
+#[test_case]
+fn test_println_many() {
+    for _ in 0..200 {
+        println!("test_println_many output");
+    }
+}
+
+#[test_case]
+fn test_println_output() {
+    let s = "Some test string that fits on a single line";
+    println!("{}", s);
+    for (i, c) in s.chars().enumerate() {
+        let screen_char = WRITER.lock().buffer.chars[BUFFER_HEIGHT - 2][i].read();
+        assert_eq!(char::from(screen_char.ascii_character), c);
+    }
+}

tests/basic_boot.rs

@@ -0,0 +1,24 @@
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(blog_os::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+use core::panic::PanicInfo;
+
+#[no_mangle] // don't mangle the name of this function
+pub extern "C" fn _start() -> ! {
+    test_main();
+
+    loop {}
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    blog_os::test_panic_handler(info)
+}
+
+#[test_case]
+fn test_println() {
+    //println!("test_println output");
+}

tests/should_panic.rs

@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+
+use blog_os::{exit_qemu, serial_print, serial_println, QemuExitCode};
+use core::panic::PanicInfo;
+
+#[no_mangle]
+pub extern "C" fn _start() -> ! {
+    should_fail();
+    serial_println!("[test did not panic]");
+    exit_qemu(QemuExitCode::Failed);
+    loop {}
+}
+
+fn should_fail() {
+    serial_print!("should_panic::should_fail...\t");
+    assert_eq!(0, 1);
+}
+
+#[panic_handler]
+fn panic(_info: &PanicInfo) -> ! {
+    serial_println!("[ok]");
+    exit_qemu(QemuExitCode::Success);
+    loop {}
+}

x86_64-blog_os.json

@@ -1,16 +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",
+    "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
     "arch": "x86_64",
     "target-endian": "little",
     "target-pointer-width": "64",
-    "target-c-int-width": 32,
+    "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",
+    "features": "-mmx,-sse,+soft-float"
-    "rustc-abi": "x86-softfloat"
   }