Merge branch 'post-09' into post-10

Merge branch 'post-08' into post-09
Merge branch 'post-07' into post-08
2025-12-16 14:27:49 +00:00 · 2025-09-03 17:58:33 +02:00 · 2025-09-03 17:58:33 +02:00 · 2025-09-03 17:58:33 +02:00 · 2025-09-03 17:58:33 +02:00 · 2025-09-03 17:58:33 +02:00
29 changed files with 965 additions and 946 deletions
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -1,91 +0,0 @@
-branches:
-  only:
-    - staging
-    - trying
-    - master
-    - /post-.*/
-
-# Appveyor configuration template for Rust using rustup for Rust installation
-# https://github.com/starkat99/appveyor-rust
-
-## Operating System (VM environment) ##
-
-# Rust needs at least Visual Studio 2013 Appveyor OS for MSVC targets.
-os: Visual Studio 2015
-
-## Build Matrix ##
-environment:
-  matrix:
-
-### MSVC Toolchains ###
-  # Nightly 64-bit MSVC
-    - channel: nightly
-      target: x86_64-pc-windows-msvc
-      MSYS_BITS: 64
-  # Nightly 32-bit MSVC
-    - channel: nightly
-      target: i686-pc-windows-msvc
-      MSYS_BITS: 32
-
-### GNU Toolchains ###
-  # Nightly 64-bit GNU
-    - channel: nightly
-      target: x86_64-pc-windows-gnu
-      MSYS_BITS: 64
-  # Nightly 32-bit GNU
-    - channel: nightly
-      target: i686-pc-windows-gnu
-      MSYS_BITS: 32
-
-cache:
-  - '%USERPROFILE%\.cargo\bin'
-  - '%USERPROFILE%\.cargo\.crates.toml'
-
-## Install Script ##
-
-# This is the most important part of the Appveyor configuration. This installs the version of Rust
-# specified by the 'channel' and 'target' environment variables from the build matrix. This uses
-# rustup to install Rust.
-#
-# For simple configurations, instead of using the build matrix, you can simply set the
-# default-toolchain and default-host manually here.
-install:
-  - appveyor-retry appveyor DownloadFile https://win.rustup.rs/ -FileName rustup-init.exe
-  - rustup-init -yv --default-toolchain %channel% --default-host %target%
-  - set PATH=%PATH%;%USERPROFILE%\.cargo\bin
-  - rustc -vV
-  - cargo -vV
-
-  # Install qemu
-  - echo %cd%
-  - mkdir "C:\Program Files\qemu"
-  - cd "C:\Program Files\qemu"
-  - if %target%==i686-pc-windows-msvc appveyor DownloadFile "https://qemu.weilnetz.de/w32/2018/qemu-w32-setup-20180801.exe" -FileName "qemu-setup.exe"
-  - if %target%==i686-pc-windows-gnu appveyor DownloadFile "https://qemu.weilnetz.de/w32/2018/qemu-w32-setup-20180801.exe" -FileName "qemu-setup.exe"
-  - if %target%==x86_64-pc-windows-msvc appveyor DownloadFile "https://qemu.weilnetz.de/w64/2018/qemu-w64-setup-20180801.exe" -FileName "qemu-setup.exe"
-  - if %target%==x86_64-pc-windows-gnu appveyor DownloadFile "https://qemu.weilnetz.de/w64/2018/qemu-w64-setup-20180801.exe" -FileName "qemu-setup.exe"
-  - 7z x qemu-setup.exe
-  - set PATH=%PATH%;C:\Program Files\qemu
-  - cd "C:\projects\blog-os"
-
-## Build Script ##
-
-# 'cargo test' takes care of building for us, so disable Appveyor's build stage. This prevents
-# the "directory does not contain a project or solution file" error.
-build: false
-
-before_test:
-  - set PATH=C:\msys64\mingw%MSYS_BITS%\bin;C:\msys64\usr\bin;%PATH%
-  # Fix undefined references to __acrt_iob_func()
-  - sed -rie "s/#define std([[:alpha:]]+)[[:space:]]+\(__acrt_iob_func\(([[:digit:]]+)\)\)/#define std\1 (\&__iob_func()[\2])/" "C:\msys64\mingw64\x86_64-w64-mingw32\include\stdio.h"
-  - sed -rie "s/#define std([[:alpha:]]+)[[:space:]]+\(__acrt_iob_func\(([[:digit:]]+)\)\)/#define std\1 (\&__iob_func()[\2])/" "C:\msys64\mingw32\i686-w64-mingw32\include\stdio.h"
-  - rustup component add rust-src
-  - set RUST_BACKTRACE=1
-  - if not exist %USERPROFILE%\.cargo\bin\cargo-install-latest.exe cargo install cargo-install-latest
-  - cargo install-latest cargo-xbuild bootimage
-
-test_script:
-  - bootimage build
-  - if %target%==x86_64-pc-windows-gnu cargo test
-  - if %target%==x86_64-pc-windows-msvc cargo test
-  - bootimage test
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -0,0 +1,9 @@
+[unstable]
+build-std = ["core", "compiler_builtins", "alloc"]
+build-std-features = ["compiler-builtins-mem"]
+
+[build]
+target = "x86_64-blog_os.json"
+
+[target.'cfg(target_os = "none")']
+runner = "bootimage runner"
--- a/.github/workflows/code.yml
+++ b/.github/workflows/code.yml
@@ -0,0 +1,130 @@
+name: Code
+
+on:
+  push:
+    branches:
+      - '*'
+      - '!staging.tmp'
+    tags:
+      - '*'
+  schedule:
+    - cron: '40 3 * * *'   # every day at 3:40
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  check:
+    name: Check
+    strategy:
+      fail-fast: false
+      matrix:
+        platform: [
+          ubuntu-latest,
+          macos-latest,
+          windows-latest
+        ]
+    runs-on: ${{ matrix.platform }}
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v2
+      - name: Install Rust Toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: nightly
+      - name: Install `rust-src` Rustup Component
+        run: rustup component add rust-src
+      - name: Run `cargo check`
+        uses: actions-rs/cargo@v1
+        with:
+          command: check
+
+  test:
+    name: Test
+    strategy:
+      fail-fast: false
+      matrix:
+        platform: [
+          ubuntu-latest,
+          macos-latest,
+          windows-latest
+        ]
+    runs-on: ${{ matrix.platform }}
+    steps:
+      - name: Install Rust Toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: nightly
+      - name: Install bootimage
+        run: cargo install bootimage --debug
+      - name: Checkout Repository
+        uses: actions/checkout@v2
+      - name: Install Rustup Components
+        run: rustup component add rust-src llvm-tools-preview
+      - name: Run `cargo bootimage`
+        uses: actions-rs/cargo@v1
+        with:
+          command: bootimage
+
+      # install QEMU
+      - name: Install QEMU (Linux)
+        run: sudo apt update && sudo apt install qemu-system-x86
+        if: runner.os == 'Linux'
+      - name: Install QEMU (macOS)
+        run: brew install qemu
+        if: runner.os == 'macOS'
+        env:
+          HOMEBREW_NO_AUTO_UPDATE: 1
+          HOMEBREW_NO_BOTTLE_SOURCE_FALLBACK: 1
+          HOMEBREW_NO_INSTALL_CLEANUP: 1
+      - name: Install QEMU (Windows)
+        run: |
+          choco install qemu --version 2021.5.5
+          echo "$Env:Programfiles\qemu" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+        if: runner.os == 'Windows'
+        shell: pwsh
+      - name: "Print QEMU Version"
+        run: qemu-system-x86_64 --version
+
+      - name: Run `cargo test`
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+
+  check_formatting:
+    name: Check Formatting
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v2
+      - name: Install Rust Toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: nightly
+          components: rustfmt
+          override: true
+      - name: Run `cargo fmt`
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v2
+      - name: Install Rust Toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: nightly
+          components: clippy, rust-src
+          override: true
+      - name: Run `cargo clippy`
+        uses: actions-rs/cargo@v1
+        with:
+          command: clippy
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
 /target
 **/*.rs.bk
+
+.vscode
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,52 +0,0 @@
-language: rust
-
-rust:
-    - nightly
-
-os:
-  - linux
-  - osx
-  - windows
-
-notifications:
-    email:
-        on_success: never
-        on_failure: always
-
-branches:
-  only:
-    # This is where pull requests from "bors r+" are built.
-    - staging
-    # This is where pull requests from "bors try" are built.
-    - trying
-    # Build pull requests.
-    - master
-    # Build post braches
-    - /^post-.*$/
-
-cache:
-  directories:
-    - $HOME/.cargo
-    - $HOME/Library/Caches/Homebrew
-
-addons:
-  apt:
-    packages:
-      - qemu-system-x86
-  homebrew:
-    packages:
-      - qemu
-
-install:
-  - if [ $TRAVIS_OS_NAME = windows ]; then choco install qemu; export PATH="/c/Program Files/qemu:$PATH"; fi
-
-before_script:
-  - rustup component add rust-src
-  - (test -x $HOME/.cargo/bin/cargo-install-latest || cargo install cargo-install-latest)
-  - cargo install-latest cargo-xbuild bootimage cargo-cache
-
-script:
-  - bootimage build
-  - cargo test
-  - bootimage test
-  - cargo cache --autoclean
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,383 +1,159 @@
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--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,29 +2,43 @@
 name = "blog_os"
 version = "0.1.0"
 authors = ["Philipp Oppermann <dev@phil-opp.com>"]
-edition = "2018"
+edition = "2024"
+
+[[test]]
+name = "should_panic"
+harness = false
+
+[[test]]
+name = "stack_overflow"
+harness = false

 [dependencies]
-bootloader = { version = "0.4.0", features = ["map_physical_memory"]}
-volatile = "0.2.3"
-spin = "0.4.9"
-uart_16550 = "0.1.0"
-x86_64 = "0.5.2"
-pic8259_simple = "0.1.1"
-pc-keyboard = "0.3.1"
+bootloader = { version = "0.9", features = ["map_physical_memory"] }
+volatile = "0.2.6"
+spin = "0.5.2"
+x86_64 = "0.14.2"
+uart_16550 = "0.2.0"
+pic8259 = "0.10.1"
+pc-keyboard = "0.7.0"
+linked_list_allocator = "0.9.0"

 [dependencies.lazy_static]
 version = "1.0"
 features = ["spin_no_std"]

-[dev-dependencies]
-array-init = "0.0.3"
+[[bin]]
+name = "blog_os"
+test = true
+bench = false

-[profile.dev]
-panic = "abort"
-
-[profile.release]
-panic = "abort"

 [package.metadata.bootimage]
-default-target = "x86_64-blog_os.json"
+test-args = [
+    "-device",
+    "isa-debug-exit,iobase=0xf4,iosize=0x04",
+    "-serial",
+    "stdio",
+    "-display",
+    "none",
+]
+test-success-exit-code = 33 # (0x10 << 1) | 1
--- a/201
+++ b/201
@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
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+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "{}"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright {yyyy} {name of copyright owner}
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
--- a/9
+++ b/9
@@ -0,0 +1,9 @@
+The MIT License (MIT)
+
+Copyright (c) 2019 Philipp Oppermann
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
--- a/README.md
+++ b/README.md
@@ -1,25 +1,35 @@
-# Blog OS (Paging Implementation)
+# Blog OS (Heap Allocation)

-[![Build Status](https://travis-ci.org/phil-opp/blog_os.svg?branch=post-10)](https://travis-ci.org/phil-opp/blog_os/branches)
+[![Build Status](https://github.com/phil-opp/blog_os/workflows/Code/badge.svg?branch=post-10)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Code%22+branch%3Apost-10)

-This repository contains the source code for the [Paging Implementation][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.
+This repository contains the source code for the [Heap Allocation][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.

-[post]: https://os.phil-opp.com/paging-implementation/
+[post]: https://os.phil-opp.com/heap-allocation/

 **Check out the [master branch](https://github.com/phil-opp/blog_os) for more information.**

 ## Building

-You need a nightly Rust compiler. First you need to install the `cargo-xbuild` and `bootimage` tools:
+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 install cargo-xbuild bootimage
+cargo build
 ```

-Then you can build the project by running:
+To create a bootable disk image from the compiled kernel, you need to install the [`bootimage`] tool:
+
+[`bootimage`]: https://github.com/rust-osdev/bootimage

 ```
-bootimage build
+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.
@@ -33,10 +43,10 @@ You can run the disk image in [QEMU] through:
 [QEMU]: https://www.qemu.org/

 ```
-bootimage run
+cargo run
 ```

-Of course [QEMU] needs to be installed for this.
+[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:

@@ -48,7 +58,20 @@ Where `sdX` is the device name of your USB stick. **Be careful** to choose the c

 ## Testing

-To run the unit tests on the host system, execute `cargo test`. To run the integration tests in [QEMU], run `bootimage test`.
+To run the unit and integration tests, execute `cargo xtest`.

 ## License
-The source code is dual-licensed under MIT or the Apache License (Version 2.0).
+
+Licensed under either of
+
+- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
+  http://www.apache.org/licenses/LICENSE-2.0)
+- MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+
+at your option.
+
+Note that this only applies to this git branch, other branches might be licensed differently.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -1,99 +0,0 @@
-# Documentation: https://aka.ms/yaml
-
-trigger:
-  batch: true
-  branches:
-    include:
-    # This is where pull requests from "bors r+" are built.
-    - staging
-    # This is where pull requests from "bors try" are built.
-    - trying
-    # Build pull requests.
-    - master
-    # Build post braches
-    - post-*
-
-strategy:
-  matrix:
-    linux:
-      image_name: 'ubuntu-16.04'
-      rustup_toolchain: nightly
-    mac:
-      image_name: 'macos-10.13'
-      rustup_toolchain: nightly
-    windows:
-      image_name: 'vs2017-win2016'
-      rustup_toolchain: nightly
-
-pool:
-  vmImage: $(image_name)
-
-steps:
- bash: |
-    echo "Hello world from $AGENT_NAME running on $AGENT_OS"
-    echo "Reason: $BUILD_REASON"
-    echo "Requested for: $BUILD_REQUESTEDFOR"
-  displayName: 'Build Info'
-  continueOnError: true
-
- script: |
-    curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain $RUSTUP_TOOLCHAIN
-    echo "##vso[task.setvariable variable=PATH;]$PATH:$HOME/.cargo/bin"
-  condition: or(eq( variables['Agent.OS'], 'Linux' ),  eq( variables['Agent.OS'], 'Darwin' ))
-  displayName: 'Install Rust (Linux/macOS)'
-
- script: |
-    curl -sSf -o rustup-init.exe https://win.rustup.rs
-    rustup-init.exe -y --default-toolchain %RUSTUP_TOOLCHAIN%
-    echo ##vso[task.setvariable variable=PATH;]%PATH%;%USERPROFILE%\.cargo\bin
-  condition: eq( variables['Agent.OS'], 'Windows_NT' )
-  displayName: 'Install Rust (Windows)'
-
- script: |
-    rustc -Vv
-    cargo -V
-  displayName: 'Print Rust Version'
-  continueOnError: true
-
- script: rustup component add rust-src
-  displayName: 'Install Rustup Src Component'
-
- script: |
-    cargo install cargo-xbuild --debug
-    cargo install bootimage --debug
-  displayName: 'Install cargo-xbuild and bootimage'
-
- script: bootimage build
-  displayName: 'Build'
-
- script: cargo test
-  displayName: 'Unit Tests'
-
- script: sudo apt install qemu-system-x86
-  condition: eq( variables['Agent.OS'], 'Linux' )
-  displayName: 'Install QEMU (Linux)'
-
- script: |
-    export HOMEBREW_NO_AUTO_UPDATE=1
-    export HOMEBREW_NO_BOTTLE_SOURCE_FALLBACK=1
-    export HOMEBREW_NO_INSTALL_CLEANUP=1
-    brew install qemu
-  condition: eq( variables['Agent.OS'], 'Darwin' )
-  displayName: 'Install QEMU (macOS)'
-
- script: |
-    choco install qemu --limit-output --no-progress
-    echo ##vso[task.setvariable variable=PATH;]%PATH%;C:\Program Files\qemu
-    set PATH=%PATH%;C:\Program Files\qemu
-    qemu-system-x86_64 --version
-  condition: eq( variables['Agent.OS'], 'Windows_NT' )
-  displayName: 'Install QEMU (Windows)'
-
- script: bootimage test
-  displayName: 'Integration Tests'
-
- script: rustup component add rustfmt
-  displayName: 'Install Rustfmt'
-
- script: cargo fmt -- --check
-  displayName: 'Check Formatting'
--- a/bors.toml
+++ b/bors.toml
@@ -1,4 +1,4 @@
 status = [
-  "phil-opp.blog_os",
+  "Test",
 ]
 delete_merged_branches = true
--- a/src/allocator.rs
+++ b/src/allocator.rs
@@ -0,0 +1,54 @@
+use alloc::alloc::{GlobalAlloc, Layout};
+use core::ptr::null_mut;
+use linked_list_allocator::LockedHeap;
+use x86_64::{
+    VirtAddr,
+    structures::paging::{
+        FrameAllocator, Mapper, Page, PageTableFlags, Size4KiB, mapper::MapToError,
+    },
+};
+
+pub const HEAP_START: usize = 0x_4444_4444_0000;
+pub const HEAP_SIZE: usize = 100 * 1024; // 100 KiB
+
+#[global_allocator]
+static ALLOCATOR: LockedHeap = LockedHeap::empty();
+
+pub fn init_heap(
+    mapper: &mut impl Mapper<Size4KiB>,
+    frame_allocator: &mut impl FrameAllocator<Size4KiB>,
+) -> Result<(), MapToError<Size4KiB>> {
+    let page_range = {
+        let heap_start = VirtAddr::new(HEAP_START as u64);
+        let heap_end = heap_start + HEAP_SIZE - 1u64;
+        let heap_start_page = Page::containing_address(heap_start);
+        let heap_end_page = Page::containing_address(heap_end);
+        Page::range_inclusive(heap_start_page, heap_end_page)
+    };
+
+    for page in page_range {
+        let frame = frame_allocator
+            .allocate_frame()
+            .ok_or(MapToError::FrameAllocationFailed)?;
+        let flags = PageTableFlags::PRESENT | PageTableFlags::WRITABLE;
+        unsafe { mapper.map_to(page, frame, flags, frame_allocator)?.flush() };
+    }
+
+    unsafe {
+        ALLOCATOR.lock().init(HEAP_START, HEAP_SIZE);
+    }
+
+    Ok(())
+}
+
+pub struct Dummy;
+
+unsafe impl GlobalAlloc for Dummy {
+    unsafe fn alloc(&self, _layout: Layout) -> *mut u8 {
+        null_mut()
+    }
+
+    unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {
+        panic!("dealloc should be never called")
+    }
+}
--- a/src/bin/test-basic-boot.rs
+++ b/src/bin/test-basic-boot.rs
@@ -1,33 +0,0 @@
-#![cfg_attr(not(test), no_std)]
-#![cfg_attr(not(test), no_main)] // disable all Rust-level entry points
-#![cfg_attr(test, allow(unused_imports))]
-
-use blog_os::{exit_qemu, serial_println};
-use core::panic::PanicInfo;
-
-/// This function is the entry point, since the linker looks for a function
-/// named `_start` by default.
-#[cfg(not(test))]
-#[no_mangle] // don't mangle the name of this function
-pub extern "C" fn _start() -> ! {
-    serial_println!("ok");
-
-    unsafe {
-        exit_qemu();
-    }
-    loop {}
-}
-
-/// This function is called on panic.
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(info: &PanicInfo) -> ! {
-    serial_println!("failed");
-
-    serial_println!("{}", info);
-
-    unsafe {
-        exit_qemu();
-    }
-    loop {}
-}
--- a/src/bin/test-exception-breakpoint.rs
+++ b/src/bin/test-exception-breakpoint.rs
@@ -1,34 +0,0 @@
-#![no_std]
-#![cfg_attr(not(test), no_main)]
-#![cfg_attr(test, allow(dead_code, unused_macros, unused_imports))]
-
-use blog_os::{exit_qemu, serial_println};
-use core::panic::PanicInfo;
-
-#[cfg(not(test))]
-#[no_mangle]
-pub extern "C" fn _start() -> ! {
-    blog_os::interrupts::init_idt();
-
-    x86_64::instructions::interrupts::int3();
-
-    serial_println!("ok");
-
-    unsafe {
-        exit_qemu();
-    }
-    loop {}
-}
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(info: &PanicInfo) -> ! {
-    serial_println!("failed");
-
-    serial_println!("{}", info);
-
-    unsafe {
-        exit_qemu();
-    }
-    loop {}
-}
--- a/src/bin/test-exception-double-fault-stack-overflow.rs
+++ b/src/bin/test-exception-double-fault-stack-overflow.rs
@@ -1,77 +0,0 @@
-#![feature(abi_x86_interrupt)]
-#![no_std]
-#![cfg_attr(not(test), no_main)]
-#![cfg_attr(test, allow(dead_code, unused_macros, unused_imports))]
-
-use blog_os::{exit_qemu, serial_println};
-use core::panic::PanicInfo;
-use lazy_static::lazy_static;
-
-#[cfg(not(test))]
-#[no_mangle]
-#[allow(unconditional_recursion)]
-pub extern "C" fn _start() -> ! {
-    blog_os::gdt::init();
-    init_test_idt();
-
-    fn stack_overflow() {
-        stack_overflow(); // for each recursion, the return address is pushed
-    }
-
-    // trigger a stack overflow
-    stack_overflow();
-
-    serial_println!("failed");
-    serial_println!("No exception occured");
-
-    unsafe {
-        exit_qemu();
-    }
-
-    loop {}
-}
-
-/// This function is called on panic.
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(info: &PanicInfo) -> ! {
-    serial_println!("failed");
-    serial_println!("{}", info);
-
-    unsafe {
-        exit_qemu();
-    }
-
-    loop {}
-}
-
-use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
-
-lazy_static! {
-    static ref TEST_IDT: InterruptDescriptorTable = {
-        let mut idt = InterruptDescriptorTable::new();
-        unsafe {
-            idt.double_fault
-                .set_handler_fn(double_fault_handler)
-                .set_stack_index(blog_os::gdt::DOUBLE_FAULT_IST_INDEX);
-        }
-
-        idt
-    };
-}
-
-pub fn init_test_idt() {
-    TEST_IDT.load();
-}
-
-extern "x86-interrupt" fn double_fault_handler(
-    _stack_frame: &mut InterruptStackFrame,
-    _error_code: u64,
-) {
-    serial_println!("ok");
-
-    unsafe {
-        exit_qemu();
-    }
-    loop {}
-}
--- a/src/bin/test-panic.rs
+++ b/src/bin/test-panic.rs
@@ -1,23 +0,0 @@
-#![cfg_attr(not(test), no_std)]
-#![cfg_attr(not(test), no_main)]
-#![cfg_attr(test, allow(unused_imports))]
-
-use blog_os::{exit_qemu, serial_println};
-use core::panic::PanicInfo;
-
-#[cfg(not(test))]
-#[no_mangle]
-pub extern "C" fn _start() -> ! {
-    panic!();
-}
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &PanicInfo) -> ! {
-    serial_println!("ok");
-
-    unsafe {
-        exit_qemu();
-    }
-    loop {}
-}
--- a/src/gdt.rs
+++ b/src/gdt.rs
@@ -1,7 +1,7 @@
 use lazy_static::lazy_static;
+use x86_64::VirtAddr;
 use x86_64::structures::gdt::{Descriptor, GlobalDescriptorTable, SegmentSelector};
 use x86_64::structures::tss::TaskStateSegment;
-use x86_64::VirtAddr;

 pub const DOUBLE_FAULT_IST_INDEX: u16 = 0;

@@ -9,10 +9,10 @@ lazy_static! {
    static ref TSS: TaskStateSegment = {
        let mut tss = TaskStateSegment::new();
        tss.interrupt_stack_table[DOUBLE_FAULT_IST_INDEX as usize] = {
-            const STACK_SIZE: usize = 4096;
+            const STACK_SIZE: usize = 4096 * 5;
            static mut STACK: [u8; STACK_SIZE] = [0; STACK_SIZE];

-            let stack_start = VirtAddr::from_ptr(unsafe { &STACK });
+            let stack_start = VirtAddr::from_ptr(&raw const STACK);
            let stack_end = stack_start + STACK_SIZE;
            stack_end
        };
@@ -41,12 +41,12 @@ struct Selectors {
 }

 pub fn init() {
-    use x86_64::instructions::segmentation::set_cs;
+    use x86_64::instructions::segmentation::{CS, Segment};
    use x86_64::instructions::tables::load_tss;

    GDT.0.load();
    unsafe {
-        set_cs(GDT.1.code_selector);
+        CS::set_reg(GDT.1.code_selector);
        load_tss(GDT.1.tss_selector);
    }
 }
--- a/src/interrupts.rs
+++ b/src/interrupts.rs
@@ -1,12 +1,6 @@
-// The x86-interrupt calling convention leads to the following LLVM error
-// when compiled for a Windows target: "offset is not a multiple of 16". This
-// happens for example when running `cargo test` on Windows. To avoid this
-// problem we skip compilation of this module on Windows.
-#![cfg(not(windows))]
-
 use crate::{gdt, hlt_loop, print, println};
 use lazy_static::lazy_static;
-use pic8259_simple::ChainedPics;
+use pic8259::ChainedPics;
 use spin;
 use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame, PageFaultErrorCode};

@@ -53,32 +47,31 @@ pub fn init_idt() {
    IDT.load();
 }

-extern "x86-interrupt" fn breakpoint_handler(stack_frame: &mut InterruptStackFrame) {
+extern "x86-interrupt" fn breakpoint_handler(stack_frame: InterruptStackFrame) {
    println!("EXCEPTION: BREAKPOINT\n{:#?}", stack_frame);
 }

 extern "x86-interrupt" fn page_fault_handler(
-    stack_frame: &mut InterruptStackFrame,
-    _error_code: PageFaultErrorCode,
+    stack_frame: InterruptStackFrame,
+    error_code: PageFaultErrorCode,
 ) {
-    use crate::hlt_loop;
    use x86_64::registers::control::Cr2;

    println!("EXCEPTION: PAGE FAULT");
    println!("Accessed Address: {:?}", Cr2::read());
+    println!("Error Code: {:?}", error_code);
    println!("{:#?}", stack_frame);
    hlt_loop();
 }

 extern "x86-interrupt" fn double_fault_handler(
-    stack_frame: &mut InterruptStackFrame,
+    stack_frame: InterruptStackFrame,
    _error_code: u64,
-) {
-    println!("EXCEPTION: DOUBLE FAULT\n{:#?}", stack_frame);
-    hlt_loop();
+) -> ! {
+    panic!("EXCEPTION: DOUBLE FAULT\n{:#?}", stack_frame);
 }

-extern "x86-interrupt" fn timer_interrupt_handler(_stack_frame: &mut InterruptStackFrame) {
+extern "x86-interrupt" fn timer_interrupt_handler(_stack_frame: InterruptStackFrame) {
    print!(".");
    unsafe {
        PICS.lock()
@@ -86,18 +79,22 @@ extern "x86-interrupt" fn timer_interrupt_handler(_stack_frame: &mut InterruptSt
    }
 }

-extern "x86-interrupt" fn keyboard_interrupt_handler(_stack_frame: &mut InterruptStackFrame) {
-    use pc_keyboard::{layouts, DecodedKey, Keyboard, ScancodeSet1};
+extern "x86-interrupt" fn keyboard_interrupt_handler(_stack_frame: InterruptStackFrame) {
+    use pc_keyboard::{DecodedKey, HandleControl, Keyboard, ScancodeSet1, layouts};
    use spin::Mutex;
    use x86_64::instructions::port::Port;

    lazy_static! {
        static ref KEYBOARD: Mutex<Keyboard<layouts::Us104Key, ScancodeSet1>> =
-            Mutex::new(Keyboard::new(layouts::Us104Key, ScancodeSet1));
+            Mutex::new(Keyboard::new(
+                ScancodeSet1::new(),
+                layouts::Us104Key,
+                HandleControl::Ignore
+            ));
    }

    let mut keyboard = KEYBOARD.lock();
-    let port = Port::new(0x60);
+    let mut port = Port::new(0x60);

    let scancode: u8 = unsafe { port.read() };
    if let Ok(Some(key_event)) = keyboard.add_byte(scancode) {
@@ -114,3 +111,9 @@ extern "x86-interrupt" fn keyboard_interrupt_handler(_stack_frame: &mut Interrup
            .notify_end_of_interrupt(InterruptIndex::Keyboard.as_u8());
    }
 }
+
+#[test_case]
+fn test_breakpoint_exception() {
+    // invoke a breakpoint exception
+    x86_64::instructions::interrupts::int3();
+}
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,17 +1,70 @@
-#![cfg_attr(not(test), no_std)]
+#![no_std]
+#![cfg_attr(test, no_main)]
+#![feature(custom_test_frameworks)]
 #![feature(abi_x86_interrupt)]
+#![test_runner(crate::test_runner)]
+#![reexport_test_harness_main = "test_main"]

+extern crate alloc;
+use core::panic::PanicInfo;
+
+pub mod allocator;
 pub mod gdt;
 pub mod interrupts;
 pub mod memory;
 pub mod serial;
 pub mod vga_buffer;

-pub unsafe fn exit_qemu() {
+pub fn init() {
+    gdt::init();
+    interrupts::init_idt();
+    unsafe { interrupts::PICS.lock().initialize() };
+    x86_64::instructions::interrupts::enable();
+}
+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);
+    hlt_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;

-    let mut port = Port::<u32>::new(0xf4);
-    port.write(0);
+    unsafe {
+        let mut port = Port::new(0xf4);
+        port.write(exit_code as u32);
+    }
 }

 pub fn hlt_loop() -> ! {
@@ -19,3 +72,23 @@ pub fn hlt_loop() -> ! {
        x86_64::instructions::hlt();
    }
 }
+
+#[cfg(test)]
+use bootloader::{BootInfo, entry_point};
+
+#[cfg(test)]
+entry_point!(test_kernel_main);
+
+/// Entry point for `cargo xtest`
+#[cfg(test)]
+fn test_kernel_main(_boot_info: &'static BootInfo) -> ! {
+    init();
+    test_main();
+    hlt_loop();
+}
+
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    test_panic_handler(info)
+}
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,36 +1,58 @@
-#![cfg_attr(not(test), no_std)]
-#![cfg_attr(not(test), no_main)]
-#![cfg_attr(test, allow(unused_imports))]
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(blog_os::test_runner)]
+#![reexport_test_harness_main = "test_main"]

+extern crate alloc;
+
+use alloc::{boxed::Box, rc::Rc, vec, vec::Vec};
 use blog_os::println;
-use bootloader::{entry_point, BootInfo};
+use bootloader::{BootInfo, entry_point};
 use core::panic::PanicInfo;

 entry_point!(kernel_main);

-#[cfg(not(test))]
 fn kernel_main(boot_info: &'static BootInfo) -> ! {
-    use blog_os::interrupts::PICS;
-    use blog_os::memory;
-    use x86_64::{structures::paging::Page, VirtAddr};
+    use blog_os::allocator;
+    use blog_os::memory::{self, BootInfoFrameAllocator};
+    use x86_64::VirtAddr;

    println!("Hello World{}", "!");
+    blog_os::init();

-    blog_os::gdt::init();
-    blog_os::interrupts::init_idt();
-    unsafe { PICS.lock().initialize() };
-    x86_64::instructions::interrupts::enable();
+    let phys_mem_offset = VirtAddr::new(boot_info.physical_memory_offset);
+    let mut mapper = unsafe { memory::init(phys_mem_offset) };
+    let mut frame_allocator = unsafe { BootInfoFrameAllocator::init(&boot_info.memory_map) };

-    let mut mapper = unsafe { memory::init(boot_info.physical_memory_offset) };
-    let mut frame_allocator = memory::init_frame_allocator(&boot_info.memory_map);
+    allocator::init_heap(&mut mapper, &mut frame_allocator).expect("heap initialization failed");

-    // map a previously unmapped page
-    let page = Page::containing_address(VirtAddr::new(0xdeadbeaf000));
-    memory::create_example_mapping(page, &mut mapper, &mut frame_allocator);
+    // allocate a number on the heap
+    let heap_value = Box::new(41);
+    println!("heap_value at {:p}", heap_value);

-    // write the string `New!` to the screen through the new mapping
-    let page_ptr: *mut u64 = page.start_address().as_mut_ptr();
-    unsafe { page_ptr.offset(400).write_volatile(0x_f021_f077_f065_f04e) };
+    // create a dynamically sized vector
+    let mut vec = Vec::new();
+    for i in 0..500 {
+        vec.push(i);
+    }
+    println!("vec at {:p}", vec.as_slice());
+
+    // create a reference counted vector -> will be freed when count reaches 0
+    let reference_counted = Rc::new(vec![1, 2, 3]);
+    let cloned_reference = reference_counted.clone();
+    println!(
+        "current reference count is {}",
+        Rc::strong_count(&cloned_reference)
+    );
+    core::mem::drop(reference_counted);
+    println!(
+        "reference count is {} now",
+        Rc::strong_count(&cloned_reference)
+    );
+
+    #[cfg(test)]
+    test_main();

    println!("It did not crash!");
    blog_os::hlt_loop();
@@ -43,3 +65,14 @@ fn panic(info: &PanicInfo) -> ! {
    println!("{}", info);
    blog_os::hlt_loop();
 }
+
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    blog_os::test_panic_handler(info)
+}
+
+#[test_case]
+fn trivial_assertion() {
+    assert_eq!(1, 1);
+}
--- a/src/memory.rs
+++ b/src/memory.rs
@@ -1,44 +1,20 @@
 use bootloader::bootinfo::{MemoryMap, MemoryRegionType};
 use x86_64::{
-    structures::paging::{
-        FrameAllocator, MappedPageTable, Mapper, MapperAllSizes, Page, PageTable, PhysFrame,
-        Size4KiB,
-    },
    PhysAddr, VirtAddr,
+    structures::paging::{FrameAllocator, OffsetPageTable, PageTable, PhysFrame, Size4KiB},
 };

-/// Initialize a new MappedPageTable.
+/// Initialize a new OffsetPageTable.
 ///
 /// This function is unsafe because the caller must guarantee that the
 /// complete physical memory is mapped to virtual memory at the passed
 /// `physical_memory_offset`. Also, this function must be only called once
 /// to avoid aliasing `&mut` references (which is undefined behavior).
-pub unsafe fn init(physical_memory_offset: u64) -> impl MapperAllSizes {
-    let level_4_table = active_level_4_table(physical_memory_offset);
-    let phys_to_virt = move |frame: PhysFrame| -> *mut PageTable {
-        let phys = frame.start_address().as_u64();
-        let virt = VirtAddr::new(phys + physical_memory_offset);
-        virt.as_mut_ptr()
-    };
-    MappedPageTable::new(level_4_table, phys_to_virt)
-}
-
-/// Create a FrameAllocator from the passed memory map
-pub fn init_frame_allocator(
-    memory_map: &'static MemoryMap,
-) -> BootInfoFrameAllocator<impl Iterator<Item = PhysFrame>> {
-    // get usable regions from memory map
-    let regions = memory_map
-        .iter()
-        .filter(|r| r.region_type == MemoryRegionType::Usable);
-    // map each region to its address range
-    let addr_ranges = regions.map(|r| r.range.start_addr()..r.range.end_addr());
-    // transform to an iterator of frame start addresses
-    let frame_addresses = addr_ranges.flat_map(|r| r.into_iter().step_by(4096));
-    // create `PhysFrame` types from the start addresses
-    let frames = frame_addresses.map(|addr| PhysFrame::containing_address(PhysAddr::new(addr)));
-
-    BootInfoFrameAllocator { frames }
+pub unsafe fn init(physical_memory_offset: VirtAddr) -> OffsetPageTable<'static> {
+    unsafe {
+        let level_4_table = active_level_4_table(physical_memory_offset);
+        OffsetPageTable::new(level_4_table, physical_memory_offset)
+    }
 }

 /// Returns a mutable reference to the active level 4 table.
@@ -47,54 +23,64 @@ pub fn init_frame_allocator(
 /// complete physical memory is mapped to virtual memory at the passed
 /// `physical_memory_offset`. Also, this function must be only called once
 /// to avoid aliasing `&mut` references (which is undefined behavior).
-unsafe fn active_level_4_table(physical_memory_offset: u64) -> &'static mut PageTable {
-    use x86_64::{registers::control::Cr3, VirtAddr};
+unsafe fn active_level_4_table(physical_memory_offset: VirtAddr) -> &'static mut PageTable {
+    use x86_64::registers::control::Cr3;

    let (level_4_table_frame, _) = Cr3::read();

    let phys = level_4_table_frame.start_address();
-    let virt = VirtAddr::new(phys.as_u64() + physical_memory_offset);
+    let virt = physical_memory_offset + phys.as_u64();
    let page_table_ptr: *mut PageTable = virt.as_mut_ptr();

-    &mut *page_table_ptr // unsafe
-}
-
-/// Creates an example mapping for the given page to frame `0xb8000`.
-pub fn create_example_mapping(
-    page: Page,
-    mapper: &mut impl Mapper<Size4KiB>,
-    frame_allocator: &mut impl FrameAllocator<Size4KiB>,
-) {
-    use x86_64::structures::paging::PageTableFlags as Flags;
-
-    let frame = PhysFrame::containing_address(PhysAddr::new(0xb8000));
-    let flags = Flags::PRESENT | Flags::WRITABLE;
-
-    let map_to_result = unsafe { mapper.map_to(page, frame, flags, frame_allocator) };
-    map_to_result.expect("map_to failed").flush();
+    unsafe { &mut *page_table_ptr }
 }

 /// A FrameAllocator that always returns `None`.
 pub struct EmptyFrameAllocator;

-impl FrameAllocator<Size4KiB> for EmptyFrameAllocator {
+unsafe impl FrameAllocator<Size4KiB> for EmptyFrameAllocator {
    fn allocate_frame(&mut self) -> Option<PhysFrame> {
        None
    }
 }

-pub struct BootInfoFrameAllocator<I>
-where
-    I: Iterator<Item = PhysFrame>,
-{
-    frames: I,
+/// A FrameAllocator that returns usable frames from the bootloader's memory map.
+pub struct BootInfoFrameAllocator {
+    memory_map: &'static MemoryMap,
+    next: usize,
 }

-impl<I> FrameAllocator<Size4KiB> for BootInfoFrameAllocator<I>
-where
-    I: Iterator<Item = PhysFrame>,
-{
-    fn allocate_frame(&mut self) -> Option<PhysFrame> {
-        self.frames.next()
+impl BootInfoFrameAllocator {
+    /// Create a FrameAllocator from the passed memory map.
+    ///
+    /// This function is unsafe because the caller must guarantee that the passed
+    /// memory map is valid. The main requirement is that all frames that are marked
+    /// as `USABLE` in it are really unused.
+    pub unsafe fn init(memory_map: &'static MemoryMap) -> Self {
+        BootInfoFrameAllocator {
+            memory_map,
+            next: 0,
+        }
+    }
+
+    /// Returns an iterator over the usable frames specified in the memory map.
+    fn usable_frames(&self) -> impl Iterator<Item = PhysFrame> {
+        // get usable regions from memory map
+        let regions = self.memory_map.iter();
+        let usable_regions = regions.filter(|r| r.region_type == MemoryRegionType::Usable);
+        // map each region to its address range
+        let addr_ranges = usable_regions.map(|r| r.range.start_addr()..r.range.end_addr());
+        // transform to an iterator of frame start addresses
+        let frame_addresses = addr_ranges.flat_map(|r| r.step_by(4096));
+        // create `PhysFrame` types from the start addresses
+        frame_addresses.map(|addr| PhysFrame::containing_address(PhysAddr::new(addr)))
+    }
+}
+
+unsafe impl FrameAllocator<Size4KiB> for BootInfoFrameAllocator {
+    fn allocate_frame(&mut self) -> Option<PhysFrame> {
+        let frame = self.usable_frames().nth(self.next);
+        self.next += 1;
+        frame
    }
 }
--- a/src/serial.rs
+++ b/src/serial.rs
@@ -4,7 +4,7 @@ use uart_16550::SerialPort;

 lazy_static! {
    pub static ref SERIAL1: Mutex<SerialPort> = {
-        let mut serial_port = SerialPort::new(0x3F8);
+        let mut serial_port = unsafe { SerialPort::new(0x3F8) };
        serial_port.init();
        Mutex::new(serial_port)
    };
@@ -36,5 +36,6 @@ macro_rules! serial_print {
 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)*));
+    ($fmt:expr, $($arg:tt)*) => ($crate::serial_print!(
+        concat!($fmt, "\n"), $($arg)*));
 }
--- a/src/vga_buffer.rs
+++ b/src/vga_buffer.rs
@@ -112,7 +112,7 @@ impl Writer {
        for byte in s.bytes() {
            match byte {
                // printable ASCII byte or newline
-                0x20...0x7e | b'\n' => self.write_byte(byte),
+                0x20..=0x7e | b'\n' => self.write_byte(byte),
                // not part of printable ASCII range
                _ => self.write_byte(0xfe),
            }
@@ -175,85 +175,30 @@ pub fn _print(args: fmt::Arguments) {
    });
 }

-#[cfg(test)]
-mod test {
-    use super::*;
+#[test_case]
+fn test_println_simple() {
+    println!("test_println_simple output");
+}

-    fn construct_writer() -> Writer {
-        use std::boxed::Box;
-
-        let buffer = construct_buffer();
-        Writer {
-            column_position: 0,
-            color_code: ColorCode::new(Color::Blue, Color::Magenta),
-            buffer: Box::leak(Box::new(buffer)),
-        }
-    }
-
-    fn construct_buffer() -> Buffer {
-        use array_init::array_init;
-
-        Buffer {
-            chars: array_init(|_| array_init(|_| Volatile::new(empty_char()))),
-        }
-    }
-
-    fn empty_char() -> ScreenChar {
-        ScreenChar {
-            ascii_character: b' ',
-            color_code: ColorCode::new(Color::Green, Color::Brown),
-        }
-    }
-
-    #[test]
-    fn write_byte() {
-        let mut writer = construct_writer();
-        writer.write_byte(b'X');
-        writer.write_byte(b'Y');
-
-        for (i, row) in writer.buffer.chars.iter().enumerate() {
-            for (j, screen_char) in row.iter().enumerate() {
-                let screen_char = screen_char.read();
-                if i == BUFFER_HEIGHT - 1 && j == 0 {
-                    assert_eq!(screen_char.ascii_character, b'X');
-                    assert_eq!(screen_char.color_code, writer.color_code);
-                } else if i == BUFFER_HEIGHT - 1 && j == 1 {
-                    assert_eq!(screen_char.ascii_character, b'Y');
-                    assert_eq!(screen_char.color_code, writer.color_code);
-                } else {
-                    assert_eq!(screen_char, empty_char());
-                }
-            }
-        }
-    }
-
-    #[test]
-    fn write_formatted() {
-        use core::fmt::Write;
-
-        let mut writer = construct_writer();
-        writeln!(&mut writer, "a").unwrap();
-        writeln!(&mut writer, "b{}", "c").unwrap();
-
-        for (i, row) in writer.buffer.chars.iter().enumerate() {
-            for (j, screen_char) in row.iter().enumerate() {
-                let screen_char = screen_char.read();
-                if i == BUFFER_HEIGHT - 3 && j == 0 {
-                    assert_eq!(screen_char.ascii_character, b'a');
-                    assert_eq!(screen_char.color_code, writer.color_code);
-                } else if i == BUFFER_HEIGHT - 2 && j == 0 {
-                    assert_eq!(screen_char.ascii_character, b'b');
-                    assert_eq!(screen_char.color_code, writer.color_code);
-                } else if i == BUFFER_HEIGHT - 2 && j == 1 {
-                    assert_eq!(screen_char.ascii_character, b'c');
-                    assert_eq!(screen_char.color_code, writer.color_code);
-                } else if i >= BUFFER_HEIGHT - 2 {
-                    assert_eq!(screen_char.ascii_character, b' ');
-                    assert_eq!(screen_char.color_code, writer.color_code);
-                } else {
-                    assert_eq!(screen_char, empty_char());
-                }
-            }
-        }
+#[test_case]
+fn test_println_many() {
+    for _ in 0..200 {
+        println!("test_println_many output");
    }
 }
+
+#[test_case]
+fn test_println_output() {
+    use core::fmt::Write;
+    use x86_64::instructions::interrupts;
+
+    let s = "Some test string that fits on a single line";
+    interrupts::without_interrupts(|| {
+        let mut writer = WRITER.lock();
+        writeln!(writer, "\n{}", s).expect("writeln failed");
+        for (i, c) in s.chars().enumerate() {
+            let screen_char = writer.buffer.chars[BUFFER_HEIGHT - 2][i].read();
+            assert_eq!(char::from(screen_char.ascii_character), c);
+        }
+    });
+}
--- a/tests/basic_boot.rs
+++ b/tests/basic_boot.rs
@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(blog_os::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+use blog_os::println;
+use core::panic::PanicInfo;
+
+#[unsafe(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");
+}
--- a/tests/heap_allocation.rs
+++ b/tests/heap_allocation.rs
@@ -0,0 +1,60 @@
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(blog_os::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+extern crate alloc;
+
+use alloc::{boxed::Box, vec::Vec};
+use blog_os::allocator::HEAP_SIZE;
+use bootloader::{BootInfo, entry_point};
+use core::panic::PanicInfo;
+
+entry_point!(main);
+
+fn main(boot_info: &'static BootInfo) -> ! {
+    use blog_os::allocator;
+    use blog_os::memory::{self, BootInfoFrameAllocator};
+    use x86_64::VirtAddr;
+
+    blog_os::init();
+    let phys_mem_offset = VirtAddr::new(boot_info.physical_memory_offset);
+    let mut mapper = unsafe { memory::init(phys_mem_offset) };
+    let mut frame_allocator = unsafe { BootInfoFrameAllocator::init(&boot_info.memory_map) };
+    allocator::init_heap(&mut mapper, &mut frame_allocator).expect("heap initialization failed");
+
+    test_main();
+    loop {}
+}
+
+#[test_case]
+fn simple_allocation() {
+    let heap_value_1 = Box::new(41);
+    let heap_value_2 = Box::new(13);
+    assert_eq!(*heap_value_1, 41);
+    assert_eq!(*heap_value_2, 13);
+}
+
+#[test_case]
+fn large_vec() {
+    let n = 1000;
+    let mut vec = Vec::new();
+    for i in 0..n {
+        vec.push(i);
+    }
+    assert_eq!(vec.iter().sum::<u64>(), (n - 1) * n / 2);
+}
+
+#[test_case]
+fn many_boxes() {
+    for i in 0..HEAP_SIZE {
+        let x = Box::new(i);
+        assert_eq!(*x, i);
+    }
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    blog_os::test_panic_handler(info)
+}
--- a/tests/should_panic.rs
+++ b/tests/should_panic.rs
@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+
+use blog_os::{QemuExitCode, exit_qemu, serial_print, serial_println};
+use core::panic::PanicInfo;
+
+#[unsafe(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 {}
+}
--- a/tests/stack_overflow.rs
+++ b/tests/stack_overflow.rs
@@ -0,0 +1,58 @@
+#![no_std]
+#![no_main]
+#![feature(abi_x86_interrupt)]
+
+use blog_os::{QemuExitCode, exit_qemu, serial_print, serial_println};
+use core::panic::PanicInfo;
+use lazy_static::lazy_static;
+use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+    serial_print!("stack_overflow::stack_overflow...\t");
+
+    blog_os::gdt::init();
+    init_test_idt();
+
+    // trigger a stack overflow
+    stack_overflow();
+
+    panic!("Execution continued after stack overflow");
+}
+
+#[allow(unconditional_recursion)]
+fn stack_overflow() {
+    stack_overflow(); // for each recursion, the return address is pushed
+    volatile::Volatile::new(0).read(); // prevent tail recursion optimizations
+}
+
+lazy_static! {
+    static ref TEST_IDT: InterruptDescriptorTable = {
+        let mut idt = InterruptDescriptorTable::new();
+        unsafe {
+            idt.double_fault
+                .set_handler_fn(test_double_fault_handler)
+                .set_stack_index(blog_os::gdt::DOUBLE_FAULT_IST_INDEX);
+        }
+
+        idt
+    };
+}
+
+pub fn init_test_idt() {
+    TEST_IDT.load();
+}
+
+extern "x86-interrupt" fn test_double_fault_handler(
+    _stack_frame: InterruptStackFrame,
+    _error_code: u64,
+) -> ! {
+    serial_println!("[ok]");
+    exit_qemu(QemuExitCode::Success);
+    loop {}
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    blog_os::test_panic_handler(info)
+}
--- a/x86_64-blog_os.json
+++ b/x86_64-blog_os.json
@@ -1,15 +1,16 @@
 {
    "llvm-target": "x86_64-unknown-none",
-    "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
+    "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",
+    "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"
+    "features": "-mmx,-sse,+soft-float",
+    "rustc-abi": "x86-softfloat"
  }