Print test results over serial port

Cargo.lock

@@ -25,6 +25,7 @@ dependencies = [
  "bootloader 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "spin 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "uart_16550 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "volatile 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "x86_64 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -209,6 +210,15 @@ dependencies = [
  "remove_dir_all 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "uart_16550"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "x86_64 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "unicode-width"
 version = "0.1.5"
@@ -316,6 +326,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum spin 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)" = "ceac490aa12c567115b40b7b7fceca03a6c9d53d5defea066123debc83c5dc1f"
 "checksum spin 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "44363f6f51401c34e7be73db0db371c04705d35efbe9f7d6082e03a921a32c55"
 "checksum tempdir 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)" = "15f2b5fb00ccdf689e0149d1b1b3c03fead81c2b37735d812fa8bddbbf41b6d8"
+"checksum uart_16550 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5b9392f60931fe3bf8f24e0a15ee4f51528770f1d64c48768ab66571334d95b0"
 "checksum unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "882386231c45df4700b275c7ff55b6f3698780a650026380e72dabe76fa46526"
 "checksum usize_conversions 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f70329e2cbe45d6c97a5112daad40c34cd9a4e18edb5a2a18fefeb584d8d25e5"
 "checksum ux 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "88dfeb711b61ce620c0cb6fd9f8e3e678622f0c971da2a63c4b3e25e88ed012f"

Cargo.toml

@@ -9,6 +9,7 @@ bootloader = "0.6.0"
 volatile = "0.2.3"
 spin = "0.4.9"
 x86_64 = "0.5.2"
+uart_16550 = "0.2.0"
 
 [dependencies.lazy_static]
 version = "1.0"
@@ -22,5 +23,7 @@ panic = "abort"
 
 [package.metadata.bootimage]
 default-target = "x86_64-blog_os.json"
-test-args = ["-device", "isa-debug-exit,iobase=0xf4,iosize=0x04"]
+test-args = [
+    "-device", "isa-debug-exit,iobase=0xf4,iosize=0x04", "-serial", "mon:stdio"
+]
 test-success-exit-code = 33         # (0x10 << 1) | 1

src/main.rs

@@ -6,6 +6,7 @@
 
 use core::panic::PanicInfo;
 
+mod serial;
 mod vga_buffer;
 
 #[no_mangle]
@@ -20,7 +21,7 @@ pub extern "C" fn _start() -> ! {
 
 #[cfg(test)]
 fn test_runner(tests: &[&dyn Fn()]) {
-    println!("Running {} tests", tests.len());
+    serial_println!("Running {} tests", tests.len());
     for test in tests {
         test();
     }
@@ -50,7 +51,7 @@ pub unsafe fn exit_qemu(exit_code: QemuExitCode) {
 
 #[test_case]
 fn trivial_assertion() {
-    print!("trivial assertion... ");
+    serial_print!("trivial assertion... ");
     assert_eq!(1, 1);
-    println!("[ok]");
+    serial_println!("[ok]");
 }

src/serial.rs

@@ -0,0 +1,37 @@
+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;
+    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)*));
+}