initial commit

3 years ago · ccd4631e2b
14 changed files with 710 additions and 0 deletions
--- a/.cargo/config
+++ b/.cargo/config
@ -0,0 +1,5 @@
+[build]
+target = "x86_64-xe_os.json"
+
+[target.'cfg(target_os = "none")']
+runner = "bootimage runner"
--- a/.gitignore
+++ b/.gitignore
@ -0,0 +1,5 @@
+.DS_Store
+.idea
+*.log
+tmp/
+target/
--- a/Cargo.lock
+++ b/Cargo.lock
@ -0,0 +1,104 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "array-init"
+version = "0.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "nodrop 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "bit_field"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "bitflags"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "bootloader"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "cast"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "spin 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "nodrop"
+version = "0.1.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "spin"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "uart_16550"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "x86_64 0.7.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "ux"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "volatile"
+version = "0.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "x86_64"
+version = "0.7.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "array-init 0.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bit_field 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cast 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ux 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "xe_os"
+version = "0.1.0"
+dependencies = [
+ "bootloader 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "spin 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "uart_16550 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "volatile 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "x86_64 0.7.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[metadata]
+"checksum array-init 0.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "23589ecb866b460d3a0f1278834750268c607e8e28a1b982c907219f3178cd72"
+"checksum bit_field 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ed8765909f9009617974ab6b7d332625b320b33c326b1e9321382ef1999b5d56"
+"checksum bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
+"checksum bootloader 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)" = "abfbe6cdea6367860818facc8e4a184f003cb83d7d004acaaf57baebf1949da0"
+"checksum cast 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "926013f2860c46252efceabb19f4a6b308197505082c609025aa6706c011d427"
+"checksum lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+"checksum nodrop 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)" = "72ef4a56884ca558e5ddb05a1d1e7e1bfd9a68d9ed024c21704cc98872dae1bb"
+"checksum spin 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6e63cff320ae2c57904679ba7cb63280a3dc4613885beafb148ee7bf9aa9042d"
+"checksum uart_16550 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "803ea8cb602dbb32c1a657a866d2dd79fe7dbeab0fb2ac667cb4dcc7de12a58b"
+"checksum ux 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "88dfeb711b61ce620c0cb6fd9f8e3e678622f0c971da2a63c4b3e25e88ed012f"
+"checksum volatile 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "6af0edf5b4faacc31fc51159244d78d65ec580f021afcef7bd53c04aeabc7f29"
+"checksum x86_64 0.7.5 (registry+https://github.com/rust-lang/crates.io-index)" = "997837f3913aac8f67164683258756d712376849906c8d609f844084bc03ef84"
--- a/Cargo.toml
+++ b/Cargo.toml
@ -0,0 +1,44 @@
+[package]
+name = "xe_os"
+version = "0.1.0"
+authors = ["Christine Dodrill <[email protected]>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+bootloader = "0.8.0"
+volatile = "0.2.6"
+spin = "0.5.2"
+x86_64 = "0.7.5"
+uart_16550 = "0.2.0"
+
+[dependencies.lazy_static]
+version = "1.0"
+features = ["spin_no_std"]
+
+[profile.dev]
+panic = "abort"
+
+[profile.release]
+panic = "abort"
+
+[package.metadata.bootimage]
+run-args = [
+    "-display", "curses"
+]
+test-args = [
+          "-device", "isa-debug-exit,iobase=0xf4,iosize=0x04",
+          "-display", "none",
+          "-serial", "stdio"
+]
+test-success-exit-code = 33
+test-timeout = 300
+
+[[test]]
+name = "should_panic"
+harness = false
+
+[[test]]
+name = "stack_overflow"
+harness = false
--- a/src/gdt.rs
+++ b/src/gdt.rs
@ -0,0 +1,46 @@
+use x86_64::VirtAddr;
+use x86_64::structures::tss::TaskStateSegment;
+use lazy_static::lazy_static;
+use x86_64::structures::gdt::{GlobalDescriptorTable, Descriptor, SegmentSelector};
+
+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;
+            static mut STACK: [u8; STACK_SIZE] = [0; STACK_SIZE];
+
+            let stack_start = VirtAddr::from_ptr(unsafe { &STACK });
+            let stack_end = stack_start + STACK_SIZE;
+            stack_end
+        };
+        tss
+    };
+}
+
+pub fn init() {
+    use x86_64::instructions::segmentation::set_cs;
+    use x86_64::instructions::tables::load_tss;
+
+    GDT.0.load();
+    unsafe {
+        set_cs(GDT.1.code_selector);
+        load_tss(GDT.1.tss_selector);
+    }
+}
+
+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,
+}
--- a/src/interrupts.rs
+++ b/src/interrupts.rs
@ -0,0 +1,42 @@
+use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
+use crate::{gdt, println};
+use lazy_static::lazy_static;
+
+lazy_static! {
+    static ref IDT: InterruptDescriptorTable = {
+        let mut idt = InterruptDescriptorTable::new();
+        idt.breakpoint.set_handler_fn(breakpoint_handler);
+        unsafe {
+            idt.double_fault.set_handler_fn(double_fault_handler)
+                            .set_stack_index(gdt::DOUBLE_FAULT_IST_INDEX);
+        }
+        idt
+    };
+}
+
+pub fn init_idt() {
+    IDT.load();
+}
+
+extern "x86-interrupt" fn breakpoint_handler(
+    stack_frame: &mut InterruptStackFrame)
+{
+    println!("EXCEPTION: BREAKPOINT\n{:#?}", stack_frame);
+}
+
+extern "x86-interrupt" fn double_fault_handler(
+    stack_frame: &mut InterruptStackFrame, _error_code: u64)
+{
+    panic!("EXCEPTION: DOUBLE FAULT\n{:#?}", stack_frame);
+}
+
+#[cfg(test)]
+use crate::{serial_print, serial_println};
+
+#[test_case]
+fn test_breakpoint_exception() {
+    serial_print!("test_breakpoint_exception...");
+    // invoke a breakpoint exception
+    x86_64::instructions::interrupts::int3();
+    serial_println!("[ok]");
+}
--- a/src/lib.rs
+++ b/src/lib.rs
@ -0,0 +1,64 @@
+#![no_std]
+#![cfg_attr(test, no_main)]
+#![feature(abi_x86_interrupt)]
+#![feature(custom_test_frameworks)]
+#![test_runner(crate::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+pub mod gdt;
+pub mod serial;
+pub mod interrupts;
+pub mod vga_buffer;
+
+use core::panic::PanicInfo;
+
+pub fn init() {
+    gdt::init();
+    interrupts::init_idt();
+}
+
+pub fn test_runner(tests: &[&dyn Fn()]) {
+    serial_println!("Running {} tests", tests.len());
+    for test in tests {
+        test();
+    }
+    exit_qemu(QemuExitCode::Success);
+}
+
+pub fn test_panic_handler(info: &PanicInfo) -> ! {
+    serial_println!("[failed]\n");
+    serial_println!("Error: {}\n", info);
+    exit_qemu(QemuExitCode::Failed);
+    loop {}
+}
+
+/// Entry point for `cargo xtest`
+#[cfg(test)]
+#[no_mangle]
+pub extern "C" fn _start() -> ! {
+    init();
+    test_main();
+    loop {}
+}
+
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    test_panic_handler(info)
+}
+
+#[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);
+    }
+}
--- a/src/main.rs
+++ b/src/main.rs
@ -0,0 +1,35 @@
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(xe_os::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+use core::panic::PanicInfo;
+use xe_os::println;
+
+#[no_mangle]
+pub extern "C" fn _start() -> ! {
+    xe_os::init();
+    println!("Hello World{}", "!");
+
+    #[cfg(test)]
+    test_main();
+
+    println!("It did not crash!");
+    loop {}
+}
+
+// our existing panic handler
+#[cfg(not(test))] // new attribute
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    println!("{}", info);
+    loop {}
+}
+
+// our panic handler in test mode
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    xe_os::test_panic_handler(info);
+}
--- a/src/serial.rs
+++ b/src/serial.rs
@ -0,0 +1,34 @@
+use uart_16550::SerialPort;
+use spin::Mutex;
+use lazy_static::lazy_static;
+
+lazy_static! {
+    pub static ref SERIAL1: Mutex<SerialPort> = {
+        let mut serial_port = unsafe { SerialPort::new(0x3F8) };
+        serial_port.init();
+        Mutex::new(serial_port)
+    };
+}
+
+#[doc(hidden)]
+pub fn _print(args: ::core::fmt::Arguments) {
+    use core::fmt::Write;
+    SERIAL1.lock().write_fmt(args).expect("Printing to serial failed");
+}
+
+/// Prints to the host through the serial interface.
+#[macro_export]
+macro_rules! serial_print {
+    ($($arg:tt)*) => {
+        $crate::serial::_print(format_args!($($arg)*));
+    };
+}
+
+/// Prints to the host through the serial interface, appending a newline.
+#[macro_export]
+macro_rules! serial_println {
+    () => ($crate::serial_print!("\n"));
+    ($fmt:expr) => ($crate::serial_print!(concat!($fmt, "\n")));
+    ($fmt:expr, $($arg:tt)*) => ($crate::serial_print!(
+        concat!($fmt, "\n"), $($arg)*));
+}
--- a/src/vga_buffer.rs
+++ b/src/vga_buffer.rs
@ -0,0 +1,204 @@
+use core::fmt;
+use lazy_static::lazy_static;
+use spin::Mutex;
+use volatile::Volatile;
+
+lazy_static! {
+    /// A global `Writer` instance that can be used for printing to the VGA text buffer.
+    ///
+    /// Used by the `print!` and `println!` macros.
+    pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
+        column_position: 0,
+        color_code: ColorCode::new(Color::Yellow, Color::Black),
+        buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
+    });
+}
+
+/// The standard color palette in VGA text mode.
+#[allow(dead_code)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(u8)]
+pub enum Color {
+    Black = 0,
+    Blue = 1,
+    Green = 2,
+    Cyan = 3,
+    Red = 4,
+    Magenta = 5,
+    Brown = 6,
+    LightGray = 7,
+    DarkGray = 8,
+    LightBlue = 9,
+    LightGreen = 10,
+    LightCyan = 11,
+    LightRed = 12,
+    Pink = 13,
+    Yellow = 14,
+    White = 15,
+}
+
+/// A combination of a foreground and a background color.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(transparent)]
+struct ColorCode(u8);
+
+impl ColorCode {
+    /// Create a new `ColorCode` with the given foreground and background colors.
+    fn new(foreground: Color, background: Color) -> ColorCode {
+        ColorCode((background as u8) << 4 | (foreground as u8))
+    }
+}
+
+/// A screen character in the VGA text buffer, consisting of an ASCII character and a `ColorCode`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(C)]
+struct ScreenChar {
+    ascii_character: u8,
+    color_code: ColorCode,
+}
+
+/// The height of the text buffer (normally 25 lines).
+const BUFFER_HEIGHT: usize = 25;
+/// The width of the text buffer (normally 80 columns).
+const BUFFER_WIDTH: usize = 80;
+
+/// A structure representing the VGA text buffer.
+#[repr(transparent)]
+struct Buffer {
+    chars: [[Volatile<ScreenChar>; BUFFER_WIDTH]; BUFFER_HEIGHT],
+}
+
+/// A writer type that allows writing ASCII bytes and strings to an underlying `Buffer`.
+///
+/// Wraps lines at `BUFFER_WIDTH`. Supports newline characters and implements the
+/// `core::fmt::Write` trait.
+pub struct Writer {
+    column_position: usize,
+    color_code: ColorCode,
+    buffer: &'static mut Buffer,
+}
+
+impl Writer {
+    /// Writes an ASCII byte to the buffer.
+    ///
+    /// Wraps lines at `BUFFER_WIDTH`. Supports the `\n` newline character.
+    pub fn write_byte(&mut self, byte: u8) {
+        match byte {
+            b'\n' => self.new_line(),
+            byte => {
+                if self.column_position >= BUFFER_WIDTH {
+                    self.new_line();
+                }
+
+                let row = BUFFER_HEIGHT - 1;
+                let col = self.column_position;
+
+                let color_code = self.color_code;
+                self.buffer.chars[row][col].write(ScreenChar {
+                    ascii_character: byte,
+                    color_code,
+                });
+                self.column_position += 1;
+            }
+        }
+    }
+
+    /// Writes the given ASCII string to the buffer.
+    ///
+    /// Wraps lines at `BUFFER_WIDTH`. Supports the `\n` newline character. Does **not**
+    /// support strings with non-ASCII characters, since they can't be printed in the VGA text
+    /// mode.
+    fn write_string(&mut self, s: &str) {
+        for byte in s.bytes() {
+            match byte {
+                // printable ASCII byte or newline
+                0x20..=0x7e | b'\n' => self.write_byte(byte),
+                // not part of printable ASCII range
+                _ => self.write_byte(0xfe),
+            }
+        }
+    }
+
+    /// Shifts all lines one line up and clears the last row.
+    fn new_line(&mut self) {
+        for row in 1..BUFFER_HEIGHT {
+            for col in 0..BUFFER_WIDTH {
+                let character = self.buffer.chars[row][col].read();
+                self.buffer.chars[row - 1][col].write(character);
+            }
+        }
+        self.clear_row(BUFFER_HEIGHT - 1);
+        self.column_position = 0;
+    }
+
+    /// Clears a row by overwriting it with blank characters.
+    fn clear_row(&mut self, row: usize) {
+        let blank = ScreenChar {
+            ascii_character: b' ',
+            color_code: self.color_code,
+        };
+        for col in 0..BUFFER_WIDTH {
+            self.buffer.chars[row][col].write(blank);
+        }
+    }
+}
+
+impl fmt::Write for Writer {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.write_string(s);
+        Ok(())
+    }
+}
+
+/// Like the `print!` macro in the standard library, but prints to the VGA text buffer.
+#[macro_export]
+macro_rules! print {
+    ($($arg:tt)*) => ($crate::vga_buffer::_print(format_args!($($arg)*)));
+}
+
+/// Like the `println!` macro in the standard library, but prints to the VGA text buffer.
+#[macro_export]
+macro_rules! println {
+    () => ($crate::print!("\n"));
+    ($($arg:tt)*) => ($crate::print!("{}\n", format_args!($($arg)*)));
+}
+
+/// Prints the given formatted string to the VGA text buffer through the global `WRITER` instance.
+#[doc(hidden)]
+pub fn _print(args: fmt::Arguments) {
+    use core::fmt::Write;
+    WRITER.lock().write_fmt(args).unwrap();
+}
+
+#[cfg(test)]
+use crate::{serial_print, serial_println};
+
+#[test_case]
+fn test_println_simple() {
+    serial_print!("test_println... ");
+    println!("test_println_simple output");
+    serial_println!("[ok]");
+}
+
+#[test_case]
+fn test_println_many() {
+    serial_print!("test_println_many... ");
+    for _ in 0..200 {
+        println!("test_println_many output");
+    }
+    serial_println!("[ok]");
+}
+
+#[test_case]
+fn test_println_output() {
+    serial_print!("test_println_output... ");
+
+    let s = "Some test string that fits on a single line";
+    println!("{}", s);
+    for (i, c) in s.chars().enumerate() {
+        let screen_char = WRITER.lock().buffer.chars[BUFFER_HEIGHT - 2][i].read();
+        assert_eq!(char::from(screen_char.ascii_character), c);
+    }
+
+    serial_println!("[ok]");
+}
--- a/tests/basic_boot.rs
+++ b/tests/basic_boot.rs
@ -0,0 +1,27 @@
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(xe_os::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+use core::panic::PanicInfo;
+use xe_os::{println, serial_print, serial_println};
+
+#[no_mangle] // don't mangle the name of this function
+pub extern "C" fn _start() -> ! {
+    test_main();
+
+    loop {}
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    xe_os::test_panic_handler(info);
+}
+
+#[test_case]
+fn test_println() {
+    serial_print!("test_println... ");
+    println!("test_println output");
+    serial_println!("[ok]");
+}
--- a/tests/should_panic.rs
+++ b/tests/should_panic.rs
@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+
+use core::panic::PanicInfo;
+use xe_os::{exit_qemu, serial_print, serial_println, QemuExitCode};
+
+#[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_fail... ");
+    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 +1,60 @@
+#![no_std]
+#![no_main]
+#![feature(abi_x86_interrupt)]
+
+use core::panic::PanicInfo;
+use xe_os::serial_print;
+
+#[no_mangle]
+pub extern "C" fn _start() -> ! {
+    serial_print!("stack_overflow... ");
+
+    xe_os::gdt::init();
+    init_test_idt();
+
+    stack_overflow();
+
+    panic!("Execution continued after stack overflow");
+}
+
+#[allow(unconditional_recursion)]
+fn stack_overflow() {
+    stack_overflow();
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    xe_os::test_panic_handler(info)
+}
+
+use lazy_static::lazy_static;
+use x86_64::structures::idt::InterruptDescriptorTable;
+
+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(xe_os::gdt::DOUBLE_FAULT_IST_INDEX);
+        }
+
+        idt
+    };
+}
+
+use xe_os::{exit_qemu, QemuExitCode, serial_println};
+use x86_64::structures::idt::InterruptStackFrame;
+
+extern "x86-interrupt" fn test_double_fault_handler(
+    _stack_frame: &mut InterruptStackFrame,
+    _error_code: u64,
+) {
+    serial_println!("[ok]");
+    exit_qemu(QemuExitCode::Success);
+    loop {}
+}
+
+pub fn init_test_idt() {
+    TEST_IDT.load();
+}
--- a/x86_64-xe_os.json
+++ b/x86_64-xe_os.json
@ -0,0 +1,15 @@
+{
+    "llvm-target": "x86_64-unknown-none",
+    "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
+    "arch": "x86_64",
+    "target-endian": "little",
+    "target-pointer-width": "64",
+    "target-c-int-width": "32",
+    "os": "none",
+    "executables": true,
+    "linker-flavor": "ld.lld",
+    "linker": "rust-lld",
+    "panic-strategy": "abort",
+    "disable-redzone": true,
+    "features": "-mmx,-sse,+soft-float"
+  }