implement serial and serial println with better qemu

Cargo.toml

@@ -8,6 +8,7 @@ bootloader = "0.9"
 volatile = "0.2.6"
 spin = "0.5.2"
 x86_64 = "0.14.2"
+uart_16550 = "0.2.0"
 
 #// DO NOTE THAT IN CARGO AS OF TO MY KNOWLEDGE 2019 AND EVEN NOW IN 2024 
 #// THERE IS A BUG IN CARGO WHERE THERE ARE "duplicate lang item" ERRORS 
@@ -26,5 +27,8 @@ version = "1.0"
 features = ["spin_no_std"]
 
 [package.metadata.bootimage]
-test-args = ["-device", "isa-debug-exit,iobase=0xf4,iosize=0x04"]
+test-args = [
+     "-device", "isa-debug-exit,iobase=0xf4,iosize=0x04", "-serial", "stdio",
+     "-display", "none"
+]
 test-success-exit-code = 33         # (0x10 << 1) | 1

src/main.rs

@@ -6,15 +6,27 @@
 #![reexport_test_harness_main = "test_main"]
 
 mod vga_buffer;
+mod serial;
 use core::panic::PanicInfo;
 
 /// This function is called on panic.
+#[cfg(not(test))] // new attribute dropped ayyy
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
     println!("{}", info);
     loop {}
 }
 
+// panic handler in test mode
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    serial_println!("[failed]\n");
+    serial_println!("Error: {}\n", info);
+    exit_qemu(QemuExitCode::Failed);
+    loop {}
+}
+
 
 // from old vga implementation
 // static VGA_BUF: &[u8] = b"Hello, world!";
@@ -58,6 +70,7 @@ pub extern "C" fn _start() -> ! {
 // FOR A PROFILE IN THE CARGO.TOML FILE
 #[cfg(test)]
 fn test_runner(tests: &[&dyn Fn()]) {
+    serial_println!("Running {} tests", tests.len());
     println!("Running {} tests", tests.len());
     for test in tests {
         test();
@@ -68,9 +81,9 @@ fn test_runner(tests: &[&dyn Fn()]) {
 
 #[test_case]
 fn trivial_assertion() {
-    print!("trivial assertion... ");
-    assert_eq!(1, 1);
-    println!("[ok]");
+    serial_print!("trivial assertion... ");
+    assert_eq!(0, 1);
+    serial_println!("[ok]");
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]

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)*));
+}