Compare commits
No commits in common. "ebbd8da3332cc93a719f5af2379dfe9f58324314" and "07346f758c4fc15dd24e3f99e082f6d81049271f" have entirely different histories.
ebbd8da333
...
07346f758c
3
.gitignore
vendored
3
.gitignore
vendored
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@ -1,5 +1,4 @@
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target
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/kernel/Cargo.lock
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/kernel/target
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/build
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/binutils
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/gcc
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2
kernel/std/Cargo.lock → kernel/Cargo.lock
generated
2
kernel/std/Cargo.lock → kernel/Cargo.lock
generated
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@ -3,5 +3,5 @@
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version = 3
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[[package]]
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name = "std"
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name = "kernel"
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version = "0.1.0"
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@ -3,8 +3,4 @@ name = "kernel"
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version = "0.1.0"
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edition = "2021"
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[workspace]
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members = ["std"]
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[dependencies]
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std = { path = "std" }
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@ -1,16 +1,22 @@
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#![no_std]
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#![no_main]
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use std::println;
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#[no_mangle]
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pub extern "C" fn kernel_main() -> ! {
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let a = 4;
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println!("Hiii :3");
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println!("{}", a);
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let vga_buffer = 0xb8000 as *mut u8;
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let string: &[u8] = b":3";
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for (i, &byte) in string.iter().enumerate() {
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unsafe {
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*vga_buffer.offset(i as isize * 2) = byte;
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*vga_buffer.offset(i as isize * 2 + 1) = 0xf;
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}
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}
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loop {}
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}
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#[panic_handler]
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fn panic(_info: &core::panic::PanicInfo) -> ! {
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loop {}
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@ -1,8 +0,0 @@
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[package]
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name = "std"
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version = "0.1.0"
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edition = "2021"
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[dependencies]
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lazy_static = { version = "1.4.0", features = ["spin_no_std"] }
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spin = "0.9.8"
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@ -1,3 +0,0 @@
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#![no_std]
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pub mod vga_buffer;
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@ -1,132 +0,0 @@
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use core::fmt::{self, Write};
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use lazy_static::lazy_static;
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use spin::Mutex;
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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#[repr(u8)]
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pub enum Color {
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Black = 0,
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Blue = 1,
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Green = 2,
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Cyan = 3,
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Red = 4,
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Magenta = 5,
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Brown = 6,
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LightGray = 7,
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DarkGray = 8,
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LightBlue = 9,
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LightGreen = 10,
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LightCyan = 11,
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LightRed = 12,
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Pink = 13,
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Yellow = 14,
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White = 15,
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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#[repr(transparent)]
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pub struct ColorCode(u8);
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impl ColorCode {
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pub fn new(foreground: Color, background: Color) -> ColorCode {
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ColorCode((background as u8) << 4 | (foreground as u8))
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}
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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#[repr(C)]
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struct ScreenChar {
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ascii_character: u8,
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color_code: ColorCode,
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}
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const BUFFER_HEIGHT: usize = 25;
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const BUFFER_WIDTH: usize = 80;
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#[repr(transparent)]
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struct Buffer {
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chars: [[ScreenChar; BUFFER_WIDTH]; BUFFER_HEIGHT],
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}
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pub struct Writer {
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col: usize,
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row: usize,
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buffer: &'static mut Buffer,
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}
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impl Writer {
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pub fn write_byte(&mut self, byte: u8) {
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self.write_byte_color(byte, ColorCode::new(Color::White, Color::Black));
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}
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pub fn write_byte_color(&mut self, byte: u8, color: ColorCode) {
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match byte {
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b'\n' => self.new_line(),
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byte => {
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if self.col >= BUFFER_WIDTH {
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self.new_line();
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}
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let row = self.row;
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let col = self.col;
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let color_code = color;
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self.buffer.chars[row][col] = ScreenChar {
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ascii_character: byte,
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color_code,
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};
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self.col += 1;
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}
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}
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}
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pub fn write_string(&mut self, s: &str) {
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self.write_string_color(s, ColorCode::new(Color::White, Color::Black));
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}
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pub fn write_string_color(&mut self, s: &str, color: ColorCode) {
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for char in s.bytes() {
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match char {
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0x20..=0x7e | b'\n' => self.write_byte_color(char, color),
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_ => self.write_byte(0xfe),
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}
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}
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}
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fn new_line(&mut self) {
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self.row += 1;
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self.col = 0;
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}
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}
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impl fmt::Write for Writer {
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fn write_str(&mut self, s: &str) -> fmt::Result {
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self.write_string(s);
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Ok(())
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}
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}
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lazy_static! {
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pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
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col: 0,
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row: 0,
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buffer: unsafe { &mut *(0xB8000 as *mut Buffer) },
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});
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}
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#[doc(hidden)]
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pub fn _print(args: fmt::Arguments) {
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WRITER.lock().write_fmt(args).unwrap()
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}
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#[macro_export]
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macro_rules! print {
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($($arg:tt)*) => ($crate::vga_buffer::_print(format_args!($($arg)*)));
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}
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#[macro_export]
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macro_rules! println {
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() => ($crate::print!("\n"));
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($($arg:tt)*) => ($crate::print!("{}\n", format_args!($($arg)*)));
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}
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@ -350,15 +350,6 @@ fn panic(_info: &core::panic::PanicInfo) -> ! {
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# Building the kernel
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To build the kernel I just run `cargo build` in the `kernel` directory. This will produce a binary called `kernel/target/i686-bare-metal/debug/kernel.elf`. I now have a multiboot enabled kernel :)
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# Grub
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Now to turn the kernel into a ISO file with a bootloader, I used grub. To configure grub I needed to create a directory for it. I made `build/isodir/boot/grub/grub.cfg` containing this:
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```
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menuentry "geos" {
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multiboot /boot/geos.bin
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}
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```
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Then I copied `kernel/target/i686-bare-metal/debug/kernel.elf` to `isodir/boot/geos.bin`. Then I ran `grub-mkrescue -o build/geos.iso build/isodir` to make an ISO containing my OS and grub. Yippee
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# File structure
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```
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geos/
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@ -1,189 +0,0 @@
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# VGA text
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Hello. Today I succesfully made a `println!` macro.
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## std
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To following conventions I decided to make a `std` library. To do this I made a workspace in `kernel/`.
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`kernel/Cargo.toml`
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```toml
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[package]
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name = "kernel"
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version = "0.1.0"
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edition = "2021"
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[workspace]
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members = ["std"]
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[dependencies]
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std = { path = "std" }
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```
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## lib.rs
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To not have one big spaghetti file I separated out all the individal modules into different files.
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`kernel/std/src/lib.rs`
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```rust
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#![no_std]
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pub mod vga_buffer;
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```
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## vga_buffer.rs
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First step for a VGA text driver is to be able to represent data.
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`kernel/std/src/lib.rs`
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```rust
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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#[repr(u8)]
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pub enum Color {
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Black = 0,
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Blue = 1,
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Green = 2,
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Cyan = 3,
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Red = 4,
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Magenta = 5,
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Brown = 6,
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LightGray = 7,
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DarkGray = 8,
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LightBlue = 9,
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LightGreen = 10,
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LightCyan = 11,
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LightRed = 12,
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Pink = 13,
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Yellow = 14,
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White = 15,
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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#[repr(transparent)] // Store this as a u8
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pub struct ColorCode(u8);
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impl ColorCode {
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pub fn new(foreground: Color, background: Color) -> ColorCode {
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ColorCode((background as u8) << 4 | (foreground as u8))
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}
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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#[repr(C)] // Tells rust to store this like a struct in C, i.e. store this as 2 bytes
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struct ScreenChar {
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ascii_character: u8,
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color_code: ColorCode,
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}
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const BUFFER_HEIGHT: usize = 25;
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const BUFFER_WIDTH: usize = 80;
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#[repr(transparent)]
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struct Buffer {
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chars: [[ScreenChar; BUFFER_WIDTH]; BUFFER_HEIGHT],
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}
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```
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Now I can represent the VGA text buffer. To write to this I want to make a writer struct that implements `fmt::Write`.
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```rust
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pub struct Writer {
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col: usize,
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row: usize,
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buffer: &'static mut Buffer,
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}
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impl Writer {
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pub fn write_byte(&mut self, byte: u8) {
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self.write_byte_color(byte, ColorCode::new(Color::White, Color::Black));
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}
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pub fn write_byte_color(&mut self, byte: u8, color: ColorCode) {
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match byte {
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b'\n' => self.new_line(),
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byte => {
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if self.col >= BUFFER_WIDTH {
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self.new_line();
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}
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let row = self.row;
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let col = self.col;
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let color_code = color;
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self.buffer.chars[row][col] = ScreenChar {
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ascii_character: byte,
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color_code,
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};
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self.col += 1;
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}
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}
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}
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pub fn write_string(&mut self, s: &str) {
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self.write_string_color(s, ColorCode::new(Color::White, Color::Black));
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}
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pub fn write_string_color(&mut self, s: &str, color: ColorCode) {
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for char in s.bytes() {
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match char {
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0x20..=0x7e | b'\n' => self.write_byte_color(char, color), // Ascii Character
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_ => self.write_byte(0xfe), // Non ascii
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}
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}
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}
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fn new_line(&mut self) {
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self.row += 1;
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self.col = 0;
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}
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}
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impl fmt::Write for Writer {
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fn write_str(&mut self, s: &str) -> fmt::Result {
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self.write_string(s);
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Ok(())
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}
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}
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```
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The problem now becomes that I can create a `Writer` but I don't have a global position, so it will just overwrite what I wrote last time. To solve this I can use a static variable. But a static variable won't be mutable. This can be solved with `Mutex` in the spin crate and `lazy_static`.
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`kernel/std/Cargo.toml`
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```toml
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[package]
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name = "std"
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version = "0.1.0"
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edition = "2021"
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[dependencies]
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lazy_static = { version = "1.4.0", features = ["spin_no_std"] }
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spin = "0.9.8"
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```
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and to make a static variable I wrote (copied from [here](https://os.phil-opp.com/vga-text-mode/)) this
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```rust
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lazy_static! {
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pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
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col: 0,
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row: 0,
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buffer: unsafe { &mut *(0xB8000 as *mut Buffer) },
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});
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}
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```
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in `kernel/std/src/vga_buffer.rs`.
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Last step is just to add a function and 2 macros
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```rust
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#[doc(hidden)]
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pub fn _print(args: fmt::Arguments) {
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WRITER.lock().write_fmt(args).unwrap()
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}
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#[macro_export]
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macro_rules! print {
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($($arg:tt)*) => ($crate::vga_buffer::_print(format_args!($($arg)*)));
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}
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#[macro_export]
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macro_rules! println {
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() => ($crate::print!("\n"));
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($($arg:tt)*) => ($crate::print!("{}\n", format_args!($($arg)*)));
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}
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```
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Huge thanks to @phil-opp for [os.phil-opp.com](https://os.phil-opp.com/)
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