Add serial logging

Signed-off-by: Noah Knegt <git@noahknegt.com>

Cargo.lock

@@ -32,6 +32,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "bit_field"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc827186963e592360843fb5ba4b973e145841266c1357f7180c43526f2e5b61"
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -107,9 +113,9 @@ checksum = "9555578bc9e57714c812a1f84e4fc5b4d21fcb063490c624de019f7464c91268"
 
 [[package]]
 name = "conquer-once"
-version = "0.3.2"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7c6d3a9775a69f6d1fe2cc888999b67ed30257d3da4d2af91984e722f2ec918a"
+checksum = "5d008a441c0f269f36ca13712528069a86a3e60dffee1d98b976eb3b0b2160b4"
 dependencies = [
  "conquer-util",
 ]
@@ -217,6 +223,8 @@ dependencies = [
  "log",
  "noto-sans-mono-bitmap",
  "spinning_top",
+ "uart_16550",
+ "x86_64",
 ]
 
 [[package]]
@@ -274,9 +282,9 @@ checksum = "32a282da65faaf38286cf3be983213fcf1d2e2a58700e808f83f4ea9a4804bc0"
 
 [[package]]
 name = "noto-sans-mono-bitmap"
-version = "0.2.0"
+version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a27daf9557165efe1d09b52f97393bf6283cadb0a76fbe64a1061e15553a994a"
+checksum = "1064d564ae026ae123bf5d607318b42a5b31d70a3c48e6ea7ee44cce4cdb095e"
 
 [[package]]
 name = "once_cell"
@@ -320,6 +328,15 @@ version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dc33ff2d4973d518d823d61aa239014831e521c75da58e3df4840d3f47749d09"
 
+[[package]]
+name = "raw-cpuid"
+version = "10.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c297679cb867470fa8c9f67dbba74a78d78e3e98d7cf2b08d6d71540f797332"
+dependencies = [
+ "bitflags 1.3.2",
+]
+
 [[package]]
 name = "rustix"
 version = "1.0.8"
@@ -394,9 +411,9 @@ dependencies = [
 
 [[package]]
 name = "spinning_top"
-version = "0.2.5"
+version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b9eb1a2f4c41445a3a0ff9abc5221c5fcd28e1f13cd7c0397706f9ac938ddb0"
+checksum = "d96d2d1d716fb500937168cc09353ffdc7a012be8475ac7308e1bdf0e3923300"
 dependencies = [
  "lock_api",
 ]
@@ -451,6 +468,17 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "uart_16550"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e492212ac378a5e00da953718dafb1340d9fbaf4f27d6f3c5cab03d931d1c049"
+dependencies = [
+ "bitflags 2.9.1",
+ "rustversion",
+ "x86",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.18"
@@ -468,6 +496,12 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "volatile"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "442887c63f2c839b346c192d047a7c87e73d0689c9157b00b53dcc27dd5ea793"
+
 [[package]]
 name = "wasi"
 version = "0.14.2+wasi-0.2.4"
@@ -698,3 +732,26 @@ checksum = "05f360fc0b24296329c78fda852a1e9ae82de9cf7b27dae4b7f62f118f77b9ed"
 dependencies = [
  "tap",
 ]
+
+[[package]]
+name = "x86"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2781db97787217ad2a2845c396a5efe286f87467a5810836db6d74926e94a385"
+dependencies = [
+ "bit_field",
+ "bitflags 1.3.2",
+ "raw-cpuid",
+]
+
+[[package]]
+name = "x86_64"
+version = "0.15.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0f042214de98141e9c8706e8192b73f56494087cc55ebec28ce10f26c5c364ae"
+dependencies = [
+ "bit_field",
+ "bitflags 2.9.1",
+ "rustversion",
+ "volatile",
+]

kernel/Cargo.toml

@@ -10,12 +10,14 @@ publish.workspace = true
 
 [dependencies]
 bootloader_api = { version = "0.11.10" }
-conquer-once = { version = "0.3.2", default-features = false }
+conquer-once = { version = "0.4.0", default-features = false }
 log = "0.4.17"
-spinning_top = "0.2.4"
+spinning_top = "0.3.0"
+uart_16550 = "0.3.2"
+x86_64 = "0.15.2"
 
 [dependencies.noto-sans-mono-bitmap]
-version = "0.2.0"
+version = "0.3.1"
 default-features = false
 features = [
     "regular",

kernel/src/logger/logger.rs

@@ -11,6 +11,7 @@ static LOGGER: OnceCell<LockedLogger> = OnceCell::uninit();
 /// A logger instance protected by a spinlock.
 struct LockedLogger {
     framebuffer: Option<Spinlock<framebuffer::FrameBufferWriter>>,
+    serial: Option<Spinlock<serial::SerialPort>>
 }
 
 impl LockedLogger {
@@ -20,9 +21,11 @@ impl LockedLogger {
         info: FrameBufferInfo,
     ) -> Self {
         let framebuffer = Some(Spinlock::new(framebuffer::FrameBufferWriter::new(framebuffer, info)));
+        let serial = Some(Spinlock::new(unsafe { serial::SerialPort::init() }));
 
         LockedLogger {
             framebuffer,
+            serial
         }
     }
 
@@ -34,6 +37,10 @@ impl LockedLogger {
         if let Some(framebuffer) = &self.framebuffer {
             unsafe { framebuffer.force_unlock() };
         }
+
+        if let Some(serial) = &self.serial {
+            unsafe { serial.force_unlock() };
+        }
     }
 }
 
@@ -47,6 +54,11 @@ impl log::Log for LockedLogger {
             let mut framebuffer = framebuffer.lock();
             writeln!(framebuffer, "{:5}: {}", record.level(), record.args()).unwrap();
         }
+
+        if let Some(serial) = &self.serial {
+            let mut serial = serial.lock();
+            writeln!(serial, "{:5}: {}", record.level(), record.args()).unwrap();
+        }
     }
 
     fn flush(&self) {}

kernel/src/logger/mod.rs

@@ -1,4 +1,5 @@
 pub mod logger;
 mod framebuffer;
+mod serial;
 
 pub use logger::*;

kernel/src/logger/serial.rs

@@ -0,0 +1,28 @@
+use core::fmt;
+
+pub struct SerialPort {
+    port: uart_16550::SerialPort,
+}
+
+impl SerialPort {
+    /// # Safety
+    ///
+    /// unsafe because this function must only be called once
+    pub unsafe fn init() -> Self {
+        let mut port = unsafe { uart_16550::SerialPort::new(0x3F8) };
+        port.init();
+        Self { port }
+    }
+}
+
+impl fmt::Write for SerialPort {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for char in s.bytes() {
+            match char {
+                b'\n' => self.port.write_str("\r\n").unwrap(),
+                byte => self.port.send(byte),
+            }
+        }
+        Ok(())
+    }
+}

kernel/src/main.rs

@@ -23,6 +23,8 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
     logger::init_logger(buffer, info);
 
     log::info!("Hello World from KERNEL");
+
+    // Endless loop as the kernel must stay running
     loop {}
 }