Rewrite VGA text driver

Cargo.toml

@@ -45,7 +45,7 @@ name = "measure_startup_time"
 harness = false
 
 [features]
-default = ["pci", "pci-ids", "acpi", "fsgsbase", "smp", "tcp", "dhcpv4", "fuse"]
+default = ["pci", "pci-ids", "acpi", "fsgsbase", "smp", "tcp", "dhcpv4", "fuse", "vga"]
 acpi = []
 dhcpv4 = [
     "smoltcp",
@@ -64,7 +64,7 @@ tcp = ["smoltcp", "smoltcp/socket-tcp"]
 udp = ["smoltcp", "smoltcp/socket-udp"]
 dns = ["smoltcp", "smoltcp/socket-dns"]
 trace = []
-vga = []
+vga = ["vga-text-mode"]
 common-os = []
 nostd = []
 semihosting = ["dep:semihosting"]
@@ -133,6 +133,7 @@ features = [
 free-list = { version = "0.3", features = ["x86_64"] }
 multiboot = "0.8"
 uart_16550 = "0.3"
+vga-text-mode = { path = "../../vga-text-mode", optional = true }
 x86 = { version = "0.52", default-features = false }
 x86_64 = "0.15"
 

src/arch/x86_64/kernel/mod.rs

@@ -140,13 +140,14 @@ pub fn message_output_init() {
 
 pub fn output_message_buf(buf: &[u8]) {
 	// Output messages to the serial port and VGA screen in unikernel mode.
+
+use alloc::string::String;
 	COM1.lock().as_mut().unwrap().send(buf);
 
 	#[cfg(feature = "vga")]
-	for &byte in buf {
-		// vga::write_byte() checks if VGA support has been initialized,
-		// so we don't need any additional if clause around it.
-		vga::write_byte(byte);
+	{
+		let s = String::from_utf8_lossy(buf);
+		vga::print(&s);
 	}
 }
 

src/arch/x86_64/kernel/vga.rs

@@ -1,134 +1,50 @@
-use x86::io::*;
+use core::alloc::Layout;
+
+use core::fmt::Write;
+use hermit_sync::{InterruptOnceCell, InterruptSpinMutex};
+use vga_text_mode::{ VgaScreen, FrontBuffer, text_buffer::TextBuffer};
+use x86_64::instructions::port::Port;
 
 use crate::arch::x86_64::mm::paging::{BasePageSize, PageTableEntryFlags, PageTableEntryFlagsExt};
 use crate::arch::x86_64::mm::{paging, PhysAddr, VirtAddr};
 
-const CRT_CONTROLLER_ADDRESS_PORT: u16 = 0x3D4;
-const CRT_CONTROLLER_DATA_PORT: u16 = 0x3D5;
-const CURSOR_START_REGISTER: u8 = 0x0A;
-const CURSOR_DISABLE: u8 = 0x20;
-
-const ATTRIBUTE_BLACK: u8 = 0x00;
-const ATTRIBUTE_LIGHTGREY: u8 = 0x07;
-const COLS: usize = 80;
-const ROWS: usize = 25;
-const VGA_BUFFER_ADDRESS: u64 = 0xB8000;
-
-static mut VGA_SCREEN: VgaScreen = VgaScreen::new();
-
-#[derive(Clone, Copy)]
-#[repr(C, packed)]
-struct VgaCharacter {
-	character: u8,
-	attribute: u8,
-}
-
-impl VgaCharacter {
-	const fn new(character: u8, attribute: u8) -> Self {
-		Self {
-			character,
-			attribute,
-		}
-	}
-}
-
-struct VgaScreen {
-	buffer: *mut [[VgaCharacter; COLS]; ROWS],
-	current_col: usize,
-	current_row: usize,
-	is_initialized: bool,
-}
-
-impl VgaScreen {
-	const fn new() -> Self {
-		Self {
-			buffer: VGA_BUFFER_ADDRESS as *mut _,
-			current_col: 0,
-			current_row: 0,
-			is_initialized: false,
-		}
-	}
-
-	fn init(&mut self) {
-		// Identity map the VGA buffer. We only need the first page.
-		let mut flags = PageTableEntryFlags::empty();
-		flags.device().writable().execute_disable();
-		paging::map::<BasePageSize>(
-			VirtAddr(VGA_BUFFER_ADDRESS),
-			PhysAddr(VGA_BUFFER_ADDRESS),
-			1,
-			flags,
-		);
+static VGA_SCREEN: InterruptOnceCell<InterruptSpinMutex<VgaScreen<'static>>> = InterruptOnceCell::new();
 
-		// Disable the cursor.
-		unsafe {
-			outb(CRT_CONTROLLER_ADDRESS_PORT, CURSOR_START_REGISTER);
-			outb(CRT_CONTROLLER_DATA_PORT, CURSOR_DISABLE);
-		}
-
-		// Clear the screen.
-		for r in 0..ROWS {
-			self.clear_row(r);
-		}
-
-		// Initialization done!
-		self.is_initialized = true;
-	}
+pub fn init() {
+	let layout = Layout::new::<TextBuffer>();
+	let virt_addr = FrontBuffer::PHYS_ADDR;
+
+	// Identity map the VGA buffer. We only need the first page.
+	let mut flags = PageTableEntryFlags::empty();
+	flags.device().writable().execute_disable();
+	paging::map::<BasePageSize>(
+		VirtAddr(virt_addr as _),
+		PhysAddr(FrontBuffer::PHYS_ADDR as u64),
+		1,
+		flags,
+	);
+
+	// Disable the cursor.
+	unsafe {
+		const CRT_CONTROLLER_ADDRESS_PORT: u16 = 0x3D4;
+		const CRT_CONTROLLER_DATA_PORT: u16 = 0x3D5;
+		const CURSOR_START_REGISTER: u8 = 0x0A;
+		const CURSOR_DISABLE: u8 = 0x20;
 
-	#[inline]
-	fn clear_row(&mut self, row: usize) {
-		// Overwrite this row by a bogus character in black.
-		for c in 0..COLS {
-			unsafe {
-				(*self.buffer)[row][c] = VgaCharacter::new(0, ATTRIBUTE_BLACK);
-			}
-		}
+		Port::new(CRT_CONTROLLER_ADDRESS_PORT).write(CURSOR_START_REGISTER);
+		Port::new(CRT_CONTROLLER_DATA_PORT).write(CURSOR_DISABLE);
 	}
 
-	fn write_byte(&mut self, byte: u8) {
-		if !self.is_initialized {
-			return;
-		}
-
-		// Move to the next row if we have a newline character or hit the end of a column.
-		if byte == b'\n' || self.current_col == COLS {
-			self.current_col = 0;
-			self.current_row += 1;
-		}
-
-		// Check if we have hit the end of the screen rows.
-		if self.current_row == ROWS {
-			// Shift all rows up by one line, removing the oldest visible screen row.
-			for r in 1..ROWS {
-				for c in 0..COLS {
-					unsafe {
-						(*self.buffer)[r - 1][c] = (*self.buffer)[r][c];
-					}
-				}
-			}
+	let front_buffer = unsafe { &mut *(virt_addr as *mut TextBuffer) };
+	let front_buffer = FrontBuffer::new(front_buffer);
 
-			// Clear the last screen row and write to it next time.
-			self.clear_row(ROWS - 1);
-			self.current_row = ROWS - 1;
-		}
-
-		if byte != b'\n' {
-			// Put our character into the VGA screen buffer and advance the column counter.
-			unsafe {
-				(*self.buffer)[self.current_row][self.current_col] =
-					VgaCharacter::new(byte, ATTRIBUTE_LIGHTGREY);
-			}
-			self.current_col += 1;
-		}
-	}
-}
-
-pub fn init() {
-	unsafe { VGA_SCREEN.init() };
+	VGA_SCREEN
+		.set(InterruptSpinMutex::new(VgaScreen::new(front_buffer)))
+		.unwrap();
 }
 
-pub fn write_byte(byte: u8) {
-	unsafe {
-		VGA_SCREEN.write_byte(byte);
+pub fn print(s: &str) {
+	if let Some(vga_screen) = VGA_SCREEN.get() {
+		vga_screen.lock().write_str(s).unwrap();
 	}
 }

xtask/src/ci/qemu.rs

@@ -77,8 +77,8 @@ impl Qemu {
 		let qemu = env::var_os("QEMU").unwrap_or_else(|| format!("qemu-system-{arch}").into());
 
 		let qemu = cmd!(sh, "{qemu}")
-			.args(&["-display", "none"])
-			.args(&["-serial", "stdio"])
+			// .args(&["-display", "none"])
+			// .args(&["-serial", "stdio"])
 			.args(&["-kernel", format!("hermit-loader-{arch}").as_ref()])
 			.args(self.machine_args())
 			.args(self.cpu_args())