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

Fix: `target-pointer-width` field now expects an integer
Fix: target-pointer-width field now expects an integer
2025-12-16 14:27:49 +00:00 · 2025-09-03 17:56:38 +02:00 · 2025-09-03 17:53:14 +02:00 · 2025-09-03 17:52:56 +02:00
25 changed files with 23 additions and 1777 deletions
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -1,5 +1,5 @@
 [unstable]
-build-std = ["core", "compiler_builtins", "alloc"]
+build-std = ["core", "compiler_builtins"]
 build-std-features = ["compiler-builtins-mem"]

 [build]
--- a/.github/workflows/code.yml
+++ b/.github/workflows/code.yml
@@ -67,31 +67,6 @@ 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 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
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,227 +2,15 @@
 # It is not intended for manual editing.
 version = 4

-[[package]]
-name = "autocfg"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"
-
-[[package]]
-name = "bit_field"
-version = "0.10.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dc827186963e592360843fb5ba4b973e145841266c1357f7180c43526f2e5b61"
-
-[[package]]
-name = "bitflags"
-version = "1.3.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
-
-[[package]]
-name = "bitflags"
-version = "2.9.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6a65b545ab31d687cff52899d4890855fec459eb6afe0da6417b8a18da87aa29"
-
 [[package]]
 name = "blog_os"
 version = "0.1.0"
 dependencies = [
 "bootloader",
- "conquer-once",
- "crossbeam-queue",
- "futures-util",
- "lazy_static",
- "linked_list_allocator",
- "pc-keyboard",
- "pic8259",
- "spin 0.5.2",
- "uart_16550",
- "volatile 0.2.7",
- "x86_64",
 ]

 [[package]]
 name = "bootloader"
-version = "0.9.32"
+version = "0.9.33"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ea119c3ed05625c179e09d17d0914570a3753ca09c890a73d98f6b72aea00d2"
-
-[[package]]
-name = "conquer-once"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "96eb12fb69466716fbae9009d389e6a30830ae8975e170eff2d2cff579f9efa3"
-dependencies = [
- "conquer-util",
-]
-
-[[package]]
-name = "conquer-util"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "654fb2472cc369d311c547103a1fa81d467bef370ae7a0680f65939895b1182a"
-
-[[package]]
-name = "crossbeam-queue"
-version = "0.3.12"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0f58bbc28f91df819d0aa2a2c00cd19754769c2fad90579b3592b1c9ba7a3115"
-dependencies = [
- "crossbeam-utils",
-]
-
-[[package]]
-name = "crossbeam-utils"
-version = "0.8.21"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
-
-[[package]]
-name = "futures-core"
-version = "0.3.31"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "05f29059c0c2090612e8d742178b0580d2dc940c837851ad723096f87af6663e"
-
-[[package]]
-name = "futures-task"
-version = "0.3.31"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f90f7dce0722e95104fcb095585910c0977252f286e354b5e3bd38902cd99988"
-
-[[package]]
-name = "futures-util"
-version = "0.3.31"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9fa08315bb612088cc391249efdc3bc77536f16c91f6cf495e6fbe85b20a4a81"
-dependencies = [
- "futures-core",
- "futures-task",
- "pin-project-lite",
- "pin-utils",
-]
-
-[[package]]
-name = "lazy_static"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
-dependencies = [
- "spin 0.9.8",
-]
-
-[[package]]
-name = "linked_list_allocator"
-version = "0.9.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "549ce1740e46b291953c4340adcd74c59bcf4308f4cac050fd33ba91b7168f4a"
-dependencies = [
- "spinning_top",
-]
-
-[[package]]
-name = "lock_api"
-version = "0.4.13"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "96936507f153605bddfcda068dd804796c84324ed2510809e5b2a624c81da765"
-dependencies = [
- "autocfg",
- "scopeguard",
-]
-
-[[package]]
-name = "pc-keyboard"
-version = "0.7.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed089a1fbffe3337a1a345501c981f1eb1e47e69de5a40e852433e12953c3174"
-
-[[package]]
-name = "pic8259"
-version = "0.10.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cb844b5b01db1e0b17938685738f113bfc903846f18932b378bc0eabfa40e194"
-dependencies = [
- "x86_64",
-]
-
-[[package]]
-name = "pin-project-lite"
-version = "0.2.16"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b3cff922bd51709b605d9ead9aa71031d81447142d828eb4a6eba76fe619f9b"
-
-[[package]]
-name = "pin-utils"
-version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
-
-[[package]]
-name = "rustversion"
-version = "1.0.22"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b39cdef0fa800fc44525c84ccb54a029961a8215f9619753635a9c0d2538d46d"
-
-[[package]]
-name = "scopeguard"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
-
-[[package]]
-name = "spin"
-version = "0.5.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6e63cff320ae2c57904679ba7cb63280a3dc4613885beafb148ee7bf9aa9042d"
-
-[[package]]
-name = "spin"
-version = "0.9.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
-
-[[package]]
-name = "spinning_top"
-version = "0.2.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b9eb1a2f4c41445a3a0ff9abc5221c5fcd28e1f13cd7c0397706f9ac938ddb0"
-dependencies = [
- "lock_api",
-]
-
-[[package]]
-name = "uart_16550"
-version = "0.2.19"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "614ff2a87880d4bd4374722268598a970bbad05ced8bf630439417347254ab2e"
-dependencies = [
- "bitflags 1.3.2",
- "rustversion",
- "x86_64",
-]
-
-[[package]]
-name = "volatile"
-version = "0.2.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f6b06ad3ed06fef1713569d547cdbdb439eafed76341820fb0e0344f29a41945"
-
-[[package]]
-name = "volatile"
-version = "0.4.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "442887c63f2c839b346c192d047a7c87e73d0689c9157b00b53dcc27dd5ea793"
-
-[[package]]
-name = "x86_64"
-version = "0.14.13"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c101112411baafbb4bf8d33e4c4a80ab5b02d74d2612331c61e8192fc9710491"
-dependencies = [
- "bit_field",
- "bitflags 2.9.2",
- "rustversion",
- "volatile 0.4.6",
-]
+checksum = "7bdfddac270bbdd45903296bc1caf29a7fdce6b326aaf0bbab7f04c5f98b7447"
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,54 +4,10 @@ version = "0.1.0"
 authors = ["Philipp Oppermann <dev@phil-opp.com>"]
 edition = "2024"

-[[test]]
-name = "should_panic"
-harness = false
-
-[[test]]
-name = "stack_overflow"
-harness = false
-
 [dependencies]
-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"]
+bootloader = "0.9"

 [[bin]]
 name = "blog_os"
-test = true
+test = false
 bench = false
-
-[dependencies.crossbeam-queue]
-version = "0.3.11"
-default-features = false
-features = ["alloc"]
-
-[dependencies.conquer-once]
-version = "0.2.0"
-default-features = false
-
-[dependencies.futures-util]
-version = "0.3.4"
-default-features = false
-features = ["alloc"]
-
-[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
--- a/README.md
+++ b/README.md
@@ -1,10 +1,10 @@
-# Blog OS (Async/Await)
+# Blog OS (A Minimal Rust Kernel)

-[![Build Status](https://github.com/phil-opp/blog_os/workflows/Code/badge.svg?branch=post-12)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Code%22+branch%3Apost-12)
+[![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 [Async/Await][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/async-await/
+[post]: https://os.phil-opp.com/minimal-rust-kernel/

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

@@ -56,10 +56,6 @@ 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
--- a/src/allocator.rs
+++ b/src/allocator.rs
@@ -1,82 +0,0 @@
-use alloc::alloc::{GlobalAlloc, Layout};
-use core::ptr::null_mut;
-use fixed_size_block::FixedSizeBlockAllocator;
-use x86_64::{
-    VirtAddr,
-    structures::paging::{
-        FrameAllocator, Mapper, Page, PageTableFlags, Size4KiB, mapper::MapToError,
-    },
-};
-
-pub mod bump;
-pub mod fixed_size_block;
-pub mod linked_list;
-
-pub const HEAP_START: usize = 0x_4444_4444_0000;
-pub const HEAP_SIZE: usize = 100 * 1024; // 100 KiB
-
-#[global_allocator]
-static ALLOCATOR: Locked<FixedSizeBlockAllocator> = Locked::new(FixedSizeBlockAllocator::new());
-
-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 wrapper around spin::Mutex to permit trait implementations.
-pub struct Locked<A> {
-    inner: spin::Mutex<A>,
-}
-
-impl<A> Locked<A> {
-    pub const fn new(inner: A) -> Self {
-        Locked {
-            inner: spin::Mutex::new(inner),
-        }
-    }
-
-    pub fn lock(&self) -> spin::MutexGuard<A> {
-        self.inner.lock()
-    }
-}
-
-/// Align the given address `addr` upwards to alignment `align`.
-///
-/// Requires that `align` is a power of two.
-fn align_up(addr: usize, align: usize) -> usize {
-    (addr + align - 1) & !(align - 1)
-}
--- a/src/allocator/bump.rs
+++ b/src/allocator/bump.rs
@@ -1,61 +0,0 @@
-use super::{Locked, align_up};
-use alloc::alloc::{GlobalAlloc, Layout};
-use core::ptr;
-
-pub struct BumpAllocator {
-    heap_start: usize,
-    heap_end: usize,
-    next: usize,
-    allocations: usize,
-}
-
-impl BumpAllocator {
-    /// Creates a new empty bump allocator.
-    pub const fn new() -> Self {
-        BumpAllocator {
-            heap_start: 0,
-            heap_end: 0,
-            next: 0,
-            allocations: 0,
-        }
-    }
-
-    /// Initializes the bump allocator with the given heap bounds.
-    ///
-    /// This method is unsafe because the caller must ensure that the given
-    /// memory range is unused. Also, this method must be called only once.
-    pub unsafe fn init(&mut self, heap_start: usize, heap_size: usize) {
-        self.heap_start = heap_start;
-        self.heap_end = heap_start.saturating_add(heap_size);
-        self.next = heap_start;
-    }
-}
-
-unsafe impl GlobalAlloc for Locked<BumpAllocator> {
-    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
-        let mut bump = self.lock(); // get a mutable reference
-
-        let alloc_start = align_up(bump.next, layout.align());
-        let alloc_end = match alloc_start.checked_add(layout.size()) {
-            Some(end) => end,
-            None => return ptr::null_mut(),
-        };
-
-        if alloc_end > bump.heap_end {
-            ptr::null_mut() // out of memory
-        } else {
-            bump.next = alloc_end;
-            bump.allocations += 1;
-            alloc_start as *mut u8
-        }
-    }
-
-    unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {
-        let mut bump = self.lock(); // get a mutable reference
-
-        bump.allocations -= 1;
-        if bump.allocations == 0 {
-            bump.next = bump.heap_start;
-        }
-    }
-}
--- a/src/allocator/fixed_size_block.rs
+++ b/src/allocator/fixed_size_block.rs
@@ -1,109 +0,0 @@
-use super::Locked;
-use alloc::alloc::{GlobalAlloc, Layout};
-use core::{
-    mem,
-    ptr::{self, NonNull},
-};
-
-/// The block sizes to use.
-///
-/// The sizes must each be power of 2 because they are also used as
-/// the block alignment (alignments must be always powers of 2).
-const BLOCK_SIZES: &[usize] = &[8, 16, 32, 64, 128, 256, 512, 1024, 2048];
-
-/// Choose an appropriate block size for the given layout.
-///
-/// Returns an index into the `BLOCK_SIZES` array.
-fn list_index(layout: &Layout) -> Option<usize> {
-    let required_block_size = layout.size().max(layout.align());
-    BLOCK_SIZES.iter().position(|&s| s >= required_block_size)
-}
-
-struct ListNode {
-    next: Option<&'static mut ListNode>,
-}
-
-pub struct FixedSizeBlockAllocator {
-    list_heads: [Option<&'static mut ListNode>; BLOCK_SIZES.len()],
-    fallback_allocator: linked_list_allocator::Heap,
-}
-
-impl FixedSizeBlockAllocator {
-    /// Creates an empty FixedSizeBlockAllocator.
-    pub const fn new() -> Self {
-        const EMPTY: Option<&'static mut ListNode> = None;
-        FixedSizeBlockAllocator {
-            list_heads: [EMPTY; BLOCK_SIZES.len()],
-            fallback_allocator: linked_list_allocator::Heap::empty(),
-        }
-    }
-
-    /// Initialize the allocator with the given heap bounds.
-    ///
-    /// This function is unsafe because the caller must guarantee that the given
-    /// heap bounds are valid and that the heap is unused. This method must be
-    /// called only once.
-    pub unsafe fn init(&mut self, heap_start: usize, heap_size: usize) {
-        unsafe {
-            self.fallback_allocator.init(heap_start, heap_size);
-        }
-    }
-
-    /// Allocates using the fallback allocator.
-    fn fallback_alloc(&mut self, layout: Layout) -> *mut u8 {
-        match self.fallback_allocator.allocate_first_fit(layout) {
-            Ok(ptr) => ptr.as_ptr(),
-            Err(_) => ptr::null_mut(),
-        }
-    }
-}
-
-unsafe impl GlobalAlloc for Locked<FixedSizeBlockAllocator> {
-    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
-        let mut allocator = self.lock();
-        match list_index(&layout) {
-            Some(index) => {
-                match allocator.list_heads[index].take() {
-                    Some(node) => {
-                        allocator.list_heads[index] = node.next.take();
-                        node as *mut ListNode as *mut u8
-                    }
-                    None => {
-                        // no block exists in list => allocate new block
-                        let block_size = BLOCK_SIZES[index];
-                        // only works if all block sizes are a power of 2
-                        let block_align = block_size;
-                        let layout = Layout::from_size_align(block_size, block_align).unwrap();
-                        allocator.fallback_alloc(layout)
-                    }
-                }
-            }
-            None => allocator.fallback_alloc(layout),
-        }
-    }
-
-    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
-        let mut allocator = self.lock();
-        match list_index(&layout) {
-            Some(index) => {
-                let new_node = ListNode {
-                    next: allocator.list_heads[index].take(),
-                };
-                // verify that block has size and alignment required for storing node
-                assert!(mem::size_of::<ListNode>() <= BLOCK_SIZES[index]);
-                assert!(mem::align_of::<ListNode>() <= BLOCK_SIZES[index]);
-                let new_node_ptr = ptr as *mut ListNode;
-                unsafe {
-                    new_node_ptr.write(new_node);
-                    allocator.list_heads[index] = Some(&mut *new_node_ptr);
-                }
-            }
-            None => {
-                let ptr = NonNull::new(ptr).unwrap();
-                unsafe {
-                    allocator.fallback_allocator.deallocate(ptr, layout);
-                }
-            }
-        }
-    }
-}
--- a/src/allocator/linked_list.rs
+++ b/src/allocator/linked_list.rs
@@ -1,151 +0,0 @@
-use super::{Locked, align_up};
-use alloc::alloc::{GlobalAlloc, Layout};
-use core::{mem, ptr};
-
-struct ListNode {
-    size: usize,
-    next: Option<&'static mut ListNode>,
-}
-
-impl ListNode {
-    const fn new(size: usize) -> Self {
-        ListNode { size, next: None }
-    }
-
-    fn start_addr(&self) -> usize {
-        self as *const Self as usize
-    }
-
-    fn end_addr(&self) -> usize {
-        self.start_addr() + self.size
-    }
-}
-
-pub struct LinkedListAllocator {
-    head: ListNode,
-}
-
-impl LinkedListAllocator {
-    /// Creates an empty LinkedListAllocator.
-    pub const fn new() -> Self {
-        Self {
-            head: ListNode::new(0),
-        }
-    }
-
-    /// Initialize the allocator with the given heap bounds.
-    ///
-    /// This function is unsafe because the caller must guarantee that the given
-    /// heap bounds are valid and that the heap is unused. This method must be
-    /// called only once.
-    pub unsafe fn init(&mut self, heap_start: usize, heap_size: usize) {
-        unsafe {
-            self.add_free_region(heap_start, heap_size);
-        }
-    }
-
-    /// Adds the given memory region to the front of the list.
-    unsafe fn add_free_region(&mut self, addr: usize, size: usize) {
-        // ensure that the freed region is capable of holding ListNode
-        assert_eq!(align_up(addr, mem::align_of::<ListNode>()), addr);
-        assert!(size >= mem::size_of::<ListNode>());
-
-        // create a new list node and append it at the start of the list
-        let mut node = ListNode::new(size);
-        node.next = self.head.next.take();
-        let node_ptr = addr as *mut ListNode;
-        unsafe {
-            node_ptr.write(node);
-            self.head.next = Some(&mut *node_ptr);
-        }
-    }
-
-    /// Looks for a free region with the given size and alignment and removes
-    /// it from the list.
-    ///
-    /// Returns a tuple of the list node and the start address of the allocation.
-    fn find_region(&mut self, size: usize, align: usize) -> Option<(&'static mut ListNode, usize)> {
-        // reference to current list node, updated for each iteration
-        let mut current = &mut self.head;
-        // look for a large enough memory region in linked list
-        while let Some(ref mut region) = current.next {
-            if let Ok(alloc_start) = Self::alloc_from_region(&region, size, align) {
-                // region suitable for allocation -> remove node from list
-                let next = region.next.take();
-                let ret = Some((current.next.take().unwrap(), alloc_start));
-                current.next = next;
-                return ret;
-            } else {
-                // region not suitable -> continue with next region
-                current = current.next.as_mut().unwrap();
-            }
-        }
-
-        // no suitable region found
-        None
-    }
-
-    /// Try to use the given region for an allocation with given size and alignment.
-    ///
-    /// Returns the allocation start address on success.
-    fn alloc_from_region(region: &ListNode, size: usize, align: usize) -> Result<usize, ()> {
-        let alloc_start = align_up(region.start_addr(), align);
-        let alloc_end = alloc_start.checked_add(size).ok_or(())?;
-
-        if alloc_end > region.end_addr() {
-            // region too small
-            return Err(());
-        }
-
-        let excess_size = region.end_addr() - alloc_end;
-        if excess_size > 0 && excess_size < mem::size_of::<ListNode>() {
-            // rest of region too small to hold a ListNode (required because the
-            // allocation splits the region in a used and a free part)
-            return Err(());
-        }
-
-        // region suitable for allocation
-        Ok(alloc_start)
-    }
-
-    /// Adjust the given layout so that the resulting allocated memory
-    /// region is also capable of storing a `ListNode`.
-    ///
-    /// Returns the adjusted size and alignment as a (size, align) tuple.
-    fn size_align(layout: Layout) -> (usize, usize) {
-        let layout = layout
-            .align_to(mem::align_of::<ListNode>())
-            .expect("adjusting alignment failed")
-            .pad_to_align();
-        let size = layout.size().max(mem::size_of::<ListNode>());
-        (size, layout.align())
-    }
-}
-
-unsafe impl GlobalAlloc for Locked<LinkedListAllocator> {
-    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
-        // perform layout adjustments
-        let (size, align) = LinkedListAllocator::size_align(layout);
-        let mut allocator = self.lock();
-
-        if let Some((region, alloc_start)) = allocator.find_region(size, align) {
-            let alloc_end = alloc_start.checked_add(size).expect("overflow");
-            let excess_size = region.end_addr() - alloc_end;
-            if excess_size > 0 {
-                unsafe {
-                    allocator.add_free_region(alloc_end, excess_size);
-                }
-            }
-            alloc_start as *mut u8
-        } else {
-            ptr::null_mut()
-        }
-    }
-
-    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
-        // perform layout adjustments
-        let (size, _) = LinkedListAllocator::size_align(layout);
-
-        unsafe { self.lock().add_free_region(ptr as usize, size) }
-    }
-}
--- a/src/gdt.rs
+++ b/src/gdt.rs
@@ -1,52 +0,0 @@
-use lazy_static::lazy_static;
-use x86_64::VirtAddr;
-use x86_64::structures::gdt::{Descriptor, GlobalDescriptorTable, SegmentSelector};
-use x86_64::structures::tss::TaskStateSegment;
-
-pub const DOUBLE_FAULT_IST_INDEX: u16 = 0;
-
-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 * 5;
-            static mut STACK: [u8; STACK_SIZE] = [0; STACK_SIZE];
-
-            let stack_start = VirtAddr::from_ptr(&raw const STACK);
-            let stack_end = stack_start + STACK_SIZE;
-            stack_end
-        };
-        tss
-    };
-}
-
-lazy_static! {
-    static ref GDT: (GlobalDescriptorTable, Selectors) = {
-        let mut gdt = GlobalDescriptorTable::new();
-        let code_selector = gdt.add_entry(Descriptor::kernel_code_segment());
-        let tss_selector = gdt.add_entry(Descriptor::tss_segment(&TSS));
-        (
-            gdt,
-            Selectors {
-                code_selector,
-                tss_selector,
-            },
-        )
-    };
-}
-
-struct Selectors {
-    code_selector: SegmentSelector,
-    tss_selector: SegmentSelector,
-}
-
-pub fn init() {
-    use x86_64::instructions::segmentation::{CS, Segment};
-    use x86_64::instructions::tables::load_tss;
-
-    GDT.0.load();
-    unsafe {
-        CS::set_reg(GDT.1.code_selector);
-        load_tss(GDT.1.tss_selector);
-    }
-}
--- a/src/interrupts.rs
+++ b/src/interrupts.rs
@@ -1,99 +0,0 @@
-use crate::{gdt, hlt_loop, print, println};
-use lazy_static::lazy_static;
-use pic8259::ChainedPics;
-use spin;
-use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame, PageFaultErrorCode};
-
-pub const PIC_1_OFFSET: u8 = 32;
-pub const PIC_2_OFFSET: u8 = PIC_1_OFFSET + 8;
-
-#[derive(Debug, Clone, Copy)]
-#[repr(u8)]
-pub enum InterruptIndex {
-    Timer = PIC_1_OFFSET,
-    Keyboard,
-}
-
-impl InterruptIndex {
-    fn as_u8(self) -> u8 {
-        self as u8
-    }
-
-    fn as_usize(self) -> usize {
-        usize::from(self.as_u8())
-    }
-}
-
-pub static PICS: spin::Mutex<ChainedPics> =
-    spin::Mutex::new(unsafe { ChainedPics::new(PIC_1_OFFSET, PIC_2_OFFSET) });
-
-lazy_static! {
-    static ref IDT: InterruptDescriptorTable = {
-        let mut idt = InterruptDescriptorTable::new();
-        idt.breakpoint.set_handler_fn(breakpoint_handler);
-        idt.page_fault.set_handler_fn(page_fault_handler);
-        unsafe {
-            idt.double_fault
-                .set_handler_fn(double_fault_handler)
-                .set_stack_index(gdt::DOUBLE_FAULT_IST_INDEX);
-        }
-        idt[InterruptIndex::Timer.as_usize()].set_handler_fn(timer_interrupt_handler);
-        idt[InterruptIndex::Keyboard.as_usize()].set_handler_fn(keyboard_interrupt_handler);
-        idt
-    };
-}
-
-pub fn init_idt() {
-    IDT.load();
-}
-
-extern "x86-interrupt" fn breakpoint_handler(stack_frame: InterruptStackFrame) {
-    println!("EXCEPTION: BREAKPOINT\n{:#?}", stack_frame);
-}
-
-extern "x86-interrupt" fn page_fault_handler(
-    stack_frame: InterruptStackFrame,
-    error_code: PageFaultErrorCode,
-) {
-    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: InterruptStackFrame,
-    _error_code: u64,
-) -> ! {
-    panic!("EXCEPTION: DOUBLE FAULT\n{:#?}", stack_frame);
-}
-
-extern "x86-interrupt" fn timer_interrupt_handler(_stack_frame: InterruptStackFrame) {
-    print!(".");
-    unsafe {
-        PICS.lock()
-            .notify_end_of_interrupt(InterruptIndex::Timer.as_u8());
-    }
-}
-
-extern "x86-interrupt" fn keyboard_interrupt_handler(_stack_frame: InterruptStackFrame) {
-    use x86_64::instructions::port::Port;
-
-    let mut port = Port::new(0x60);
-    let scancode: u8 = unsafe { port.read() };
-    crate::task::keyboard::add_scancode(scancode);
-
-    unsafe {
-        PICS.lock()
-            .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
@@ -1,95 +0,0 @@
-#![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 task;
-pub mod vga_buffer;
-
-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;
-
-    unsafe {
-        let mut port = Port::new(0xf4);
-        port.write(exit_code as u32);
-    }
-}
-
-pub fn hlt_loop() -> ! {
-    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
@@ -1,65 +1,26 @@
 #![no_std]
 #![no_main]
-#![feature(custom_test_frameworks)]
-#![test_runner(blog_os::test_runner)]
-#![reexport_test_harness_main = "test_main"]

-extern crate alloc;
-
-use blog_os::println;
-use blog_os::task::{Task, executor::Executor, keyboard};
-use bootloader::{BootInfo, entry_point};
 use core::panic::PanicInfo;

-entry_point!(kernel_main);
+static HELLO: &[u8] = b"Hello World!";

-fn kernel_main(boot_info: &'static BootInfo) -> ! {
-    use blog_os::allocator;
-    use blog_os::memory::{self, BootInfoFrameAllocator};
-    use x86_64::VirtAddr;
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+    let vga_buffer = 0xb8000 as *mut u8;

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

-    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");
-
-    #[cfg(test)]
-    test_main();
-
-    let mut executor = Executor::new();
-    executor.spawn(Task::new(example_task()));
-    executor.spawn(Task::new(keyboard::print_keypresses()));
-    executor.run();
+    loop {}
 }

 /// This function is called on panic.
-#[cfg(not(test))]
 #[panic_handler]
-fn panic(info: &PanicInfo) -> ! {
-    println!("{}", info);
-    blog_os::hlt_loop();
-}
-
-#[cfg(test)]
-#[panic_handler]
-fn panic(info: &PanicInfo) -> ! {
-    blog_os::test_panic_handler(info)
-}
-
-async fn async_number() -> u32 {
-    42
-}
-
-async fn example_task() {
-    let number = async_number().await;
-    println!("async number: {}", number);
-}
-
-#[test_case]
-fn trivial_assertion() {
-    assert_eq!(1, 1);
+fn panic(_info: &PanicInfo) -> ! {
+    loop {}
 }
--- a/src/memory.rs
+++ b/src/memory.rs
@@ -1,86 +0,0 @@
-use bootloader::bootinfo::{MemoryMap, MemoryRegionType};
-use x86_64::{
-    PhysAddr, VirtAddr,
-    structures::paging::{FrameAllocator, OffsetPageTable, PageTable, PhysFrame, Size4KiB},
-};
-
-/// 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: 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.
-///
-/// 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).
-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 = physical_memory_offset + phys.as_u64();
-    let page_table_ptr: *mut PageTable = virt.as_mut_ptr();
-
-    unsafe { &mut *page_table_ptr }
-}
-
-/// A FrameAllocator that always returns `None`.
-pub struct EmptyFrameAllocator;
-
-unsafe impl FrameAllocator<Size4KiB> for EmptyFrameAllocator {
-    fn allocate_frame(&mut self) -> Option<PhysFrame> {
-        None
-    }
-}
-
-/// A FrameAllocator that returns usable frames from the bootloader's memory map.
-pub struct BootInfoFrameAllocator {
-    memory_map: &'static MemoryMap,
-    next: usize,
-}
-
-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
@@ -1,41 +0,0 @@
-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;
-    use x86_64::instructions::interrupts;
-
-    interrupts::without_interrupts(|| {
-        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)*));
-}
--- a/src/task/executor.rs
+++ b/src/task/executor.rs
@@ -1,102 +0,0 @@
-use super::{Task, TaskId};
-use alloc::{collections::BTreeMap, sync::Arc, task::Wake};
-use core::task::{Context, Poll, Waker};
-use crossbeam_queue::ArrayQueue;
-
-pub struct Executor {
-    tasks: BTreeMap<TaskId, Task>,
-    task_queue: Arc<ArrayQueue<TaskId>>,
-    waker_cache: BTreeMap<TaskId, Waker>,
-}
-
-impl Executor {
-    pub fn new() -> Self {
-        Executor {
-            tasks: BTreeMap::new(),
-            task_queue: Arc::new(ArrayQueue::new(100)),
-            waker_cache: BTreeMap::new(),
-        }
-    }
-
-    pub fn spawn(&mut self, task: Task) {
-        let task_id = task.id;
-        if self.tasks.insert(task.id, task).is_some() {
-            panic!("task with same ID already in tasks");
-        }
-        self.task_queue.push(task_id).expect("queue full");
-    }
-
-    pub fn run(&mut self) -> ! {
-        loop {
-            self.run_ready_tasks();
-            self.sleep_if_idle();
-        }
-    }
-
-    fn run_ready_tasks(&mut self) {
-        // destructure `self` to avoid borrow checker errors
-        let Self {
-            tasks,
-            task_queue,
-            waker_cache,
-        } = self;
-
-        while let Some(task_id) = task_queue.pop() {
-            let task = match tasks.get_mut(&task_id) {
-                Some(task) => task,
-                None => continue, // task no longer exists
-            };
-            let waker = waker_cache
-                .entry(task_id)
-                .or_insert_with(|| TaskWaker::new(task_id, task_queue.clone()));
-            let mut context = Context::from_waker(waker);
-            match task.poll(&mut context) {
-                Poll::Ready(()) => {
-                    // task done -> remove it and its cached waker
-                    tasks.remove(&task_id);
-                    waker_cache.remove(&task_id);
-                }
-                Poll::Pending => {}
-            }
-        }
-    }
-
-    fn sleep_if_idle(&self) {
-        use x86_64::instructions::interrupts::{self, enable_and_hlt};
-
-        interrupts::disable();
-        if self.task_queue.is_empty() {
-            enable_and_hlt();
-        } else {
-            interrupts::enable();
-        }
-    }
-}
-
-struct TaskWaker {
-    task_id: TaskId,
-    task_queue: Arc<ArrayQueue<TaskId>>,
-}
-
-impl TaskWaker {
-    fn new(task_id: TaskId, task_queue: Arc<ArrayQueue<TaskId>>) -> Waker {
-        Waker::from(Arc::new(TaskWaker {
-            task_id,
-            task_queue,
-        }))
-    }
-
-    fn wake_task(&self) {
-        self.task_queue.push(self.task_id).expect("task_queue full");
-    }
-}
-
-impl Wake for TaskWaker {
-    fn wake(self: Arc<Self>) {
-        self.wake_task();
-    }
-
-    fn wake_by_ref(self: &Arc<Self>) {
-        self.wake_task();
-    }
-}
--- a/src/task/keyboard.rs
+++ b/src/task/keyboard.rs
@@ -1,87 +0,0 @@
-use crate::{print, println};
-use conquer_once::spin::OnceCell;
-use core::{
-    pin::Pin,
-    task::{Context, Poll},
-};
-use crossbeam_queue::ArrayQueue;
-use futures_util::{
-    stream::{Stream, StreamExt},
-    task::AtomicWaker,
-};
-use pc_keyboard::{DecodedKey, HandleControl, Keyboard, ScancodeSet1, layouts};
-
-static SCANCODE_QUEUE: OnceCell<ArrayQueue<u8>> = OnceCell::uninit();
-static WAKER: AtomicWaker = AtomicWaker::new();
-
-/// Called by the keyboard interrupt handler
-///
-/// Must not block or allocate.
-pub(crate) fn add_scancode(scancode: u8) {
-    if let Ok(queue) = SCANCODE_QUEUE.try_get() {
-        if let Err(_) = queue.push(scancode) {
-            println!("WARNING: scancode queue full; dropping keyboard input");
-        } else {
-            WAKER.wake();
-        }
-    } else {
-        println!("WARNING: scancode queue uninitialized");
-    }
-}
-
-pub struct ScancodeStream {
-    _private: (),
-}
-
-impl ScancodeStream {
-    pub fn new() -> Self {
-        SCANCODE_QUEUE
-            .try_init_once(|| ArrayQueue::new(100))
-            .expect("ScancodeStream::new should only be called once");
-        ScancodeStream { _private: () }
-    }
-}
-
-impl Stream for ScancodeStream {
-    type Item = u8;
-
-    fn poll_next(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<u8>> {
-        let queue = SCANCODE_QUEUE
-            .try_get()
-            .expect("scancode queue not initialized");
-
-        // fast path
-        if let Some(scancode) = queue.pop() {
-            return Poll::Ready(Some(scancode));
-        }
-
-        WAKER.register(&cx.waker());
-        match queue.pop() {
-            Some(scancode) => {
-                WAKER.take();
-                Poll::Ready(Some(scancode))
-            }
-            None => Poll::Pending,
-        }
-    }
-}
-
-pub async fn print_keypresses() {
-    let mut scancodes = ScancodeStream::new();
-    let mut keyboard = Keyboard::new(
-        ScancodeSet1::new(),
-        layouts::Us104Key,
-        HandleControl::Ignore,
-    );
-
-    while let Some(scancode) = scancodes.next().await {
-        if let Ok(Some(key_event)) = keyboard.add_byte(scancode) {
-            if let Some(key) = keyboard.process_keyevent(key_event) {
-                match key {
-                    DecodedKey::Unicode(character) => print!("{}", character),
-                    DecodedKey::RawKey(key) => print!("{:?}", key),
-                }
-            }
-        }
-    }
-}
--- a/src/task/mod.rs
+++ b/src/task/mod.rs
@@ -1,39 +0,0 @@
-use alloc::boxed::Box;
-use core::{
-    future::Future,
-    pin::Pin,
-    sync::atomic::{AtomicU64, Ordering},
-    task::{Context, Poll},
-};
-
-pub mod executor;
-pub mod keyboard;
-pub mod simple_executor;
-
-pub struct Task {
-    id: TaskId,
-    future: Pin<Box<dyn Future<Output = ()>>>,
-}
-
-impl Task {
-    pub fn new(future: impl Future<Output = ()> + 'static) -> Task {
-        Task {
-            id: TaskId::new(),
-            future: Box::pin(future),
-        }
-    }
-
-    fn poll(&mut self, context: &mut Context) -> Poll<()> {
-        self.future.as_mut().poll(context)
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
-struct TaskId(u64);
-
-impl TaskId {
-    fn new() -> Self {
-        static NEXT_ID: AtomicU64 = AtomicU64::new(0);
-        TaskId(NEXT_ID.fetch_add(1, Ordering::Relaxed))
-    }
-}
--- a/src/task/simple_executor.rs
+++ b/src/task/simple_executor.rs
@@ -1,44 +0,0 @@
-use super::Task;
-use alloc::collections::VecDeque;
-use core::task::{Context, Poll, RawWaker, RawWakerVTable, Waker};
-
-pub struct SimpleExecutor {
-    task_queue: VecDeque<Task>,
-}
-
-impl SimpleExecutor {
-    pub fn new() -> SimpleExecutor {
-        SimpleExecutor {
-            task_queue: VecDeque::new(),
-        }
-    }
-
-    pub fn spawn(&mut self, task: Task) {
-        self.task_queue.push_back(task)
-    }
-
-    pub fn run(&mut self) {
-        while let Some(mut task) = self.task_queue.pop_front() {
-            let waker = dummy_waker();
-            let mut context = Context::from_waker(&waker);
-            match task.poll(&mut context) {
-                Poll::Ready(()) => {} // task done
-                Poll::Pending => self.task_queue.push_back(task),
-            }
-        }
-    }
-}
-
-fn dummy_raw_waker() -> RawWaker {
-    fn no_op(_: *const ()) {}
-    fn clone(_: *const ()) -> RawWaker {
-        dummy_raw_waker()
-    }
-
-    let vtable = &RawWakerVTable::new(clone, no_op, no_op, no_op);
-    RawWaker::new(0 as *const (), vtable)
-}
-
-fn dummy_waker() -> Waker {
-    unsafe { Waker::from_raw(dummy_raw_waker()) }
-}
--- a/src/vga_buffer.rs
+++ b/src/vga_buffer.rs
@@ -1,204 +0,0 @@
-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;
-    use x86_64::instructions::interrupts;
-
-    interrupts::without_interrupts(|| {
-        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() {
-    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
@@ -1,25 +0,0 @@
-#![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
@@ -1,70 +0,0 @@
-#![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);
-    }
-}
-
-#[test_case]
-fn many_boxes_long_lived() {
-    let long_lived = Box::new(1); // new
-    for i in 0..HEAP_SIZE {
-        let x = Box::new(i);
-        assert_eq!(*x, i);
-    }
-    assert_eq!(*long_lived, 1); // new
-}
-
-#[panic_handler]
-fn panic(info: &PanicInfo) -> ! {
-    blog_os::test_panic_handler(info)
-}
--- a/tests/should_panic.rs
+++ b/tests/should_panic.rs
@@ -1,25 +0,0 @@
-#![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
@@ -1,58 +0,0 @@
-#![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
@@ -3,7 +3,7 @@
    "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-pointer-width": 64,
    "target-c-int-width": 32,
    "os": "none",
    "executables": true,
Author	SHA1	Message	Date
Philipp Oppermann	83e6c0bc00	Merge pull request #1436 from phil-opp/post-02-fix-target Fix: `target-pointer-width` field now expects an integer	2025-09-03 17:56:38 +02:00
Philipp Oppermann	2b11ad8397	Fix: `target-pointer-width` field now expects an integer	2025-09-03 17:53:14 +02:00
Philipp Oppermann	fa51f3adbf	Update to latest bootloader version	2025-09-03 17:52:56 +02:00