From 315d4d3836ed052019602589dfb99e601623fdfd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juanjo=20Asensio=20Garc=C3=ADa?= <asengar2009@gmail.com>
Date: Fri, 27 Jan 2023 16:11:34 +0100
Subject: [PATCH 1/7] Fix clippy in bootloader_api

---
 api/build.rs | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/api/build.rs b/api/build.rs
index 3621eeef..e0b1437d 100644
--- a/api/build.rs
+++ b/api/build.rs
@@ -34,11 +34,11 @@ fn main() {
             i = i,
             j = j,
             a = (0..i)
-                .map(|idx| format!("a[{}]", idx))
+                .map(|idx| format!("a[{idx}]"))
                 .collect::<Vec<_>>()
                 .join(","),
             b = (0..j)
-                .map(|idx| format!("b[{}]", idx))
+                .map(|idx| format!("b[{idx}]"))
                 .collect::<Vec<_>>()
                 .join(","),
         );
@@ -56,12 +56,11 @@ fn main() {
         Path::new(&out_dir).join("version_info.rs"),
         format!(
             "
-            pub const VERSION_MAJOR: u16 = {};
-            pub const VERSION_MINOR: u16 = {};
-            pub const VERSION_PATCH: u16 = {};
-            pub const VERSION_PRE: bool = {};
-            ",
-            version_major, version_minor, version_patch, pre_release
+            pub const VERSION_MAJOR: u16 = {version_major};
+            pub const VERSION_MINOR: u16 = {version_minor};
+            pub const VERSION_PATCH: u16 = {version_patch};
+            pub const VERSION_PRE: bool = {pre_release};
+            "
         ),
     )
     .unwrap();

From 1d9840cd8cb8f840a09d17bd24e388cf8530a32d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juanjo=20Asensio=20Garc=C3=ADa?= <asengar2009@gmail.com>
Date: Fri, 27 Jan 2023 16:30:41 +0100
Subject: [PATCH 2/7] Fix clippy in tests

---
 tests/test_kernels/config_file/src/bin/basic_boot.rs        | 4 ++--
 .../config_file/src/bin/basic_boot_broken_config_file.rs    | 4 ++--
 tests/test_kernels/default_settings/src/bin/basic_boot.rs   | 4 ++--
 .../default_settings/src/bin/check_boot_info.rs             | 2 +-
 tests/test_kernels/higher_half/src/bin/check_boot_info.rs   | 2 +-
 .../test_kernels/higher_half/src/bin/verify_higher_half.rs  | 2 +-
 tests/test_kernels/lto/src/bin/basic_boot.rs                | 2 +-
 tests/test_kernels/map_phys_mem/src/bin/access_phys_mem.rs  | 2 +-
 tests/test_kernels/map_phys_mem/src/bin/check_boot_info.rs  | 2 +-
 tests/test_kernels/pie/src/bin/basic_boot.rs                | 2 +-
 tests/test_kernels/pie/src/bin/check_boot_info.rs           | 2 +-
 tests/test_kernels/pie/src/bin/global_variable.rs           | 2 +-
 tests/test_kernels/ramdisk/src/bin/basic_boot.rs            | 2 +-
 tests/test_kernels/ramdisk/src/bin/ramdisk.rs               | 6 +++---
 14 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/tests/test_kernels/config_file/src/bin/basic_boot.rs b/tests/test_kernels/config_file/src/bin/basic_boot.rs
index d6401dc7..5232aa80 100644
--- a/tests/test_kernels/config_file/src/bin/basic_boot.rs
+++ b/tests/test_kernels/config_file/src/bin/basic_boot.rs
@@ -8,7 +8,7 @@ use test_kernel_config_file::{exit_qemu, serial, QemuExitCode};
 entry_point!(kernel_main);
 
 fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
-    writeln!(serial(), "Entered kernel with boot info: {:?}", boot_info).unwrap();
+    writeln!(serial(), "Entered kernel with boot info: {boot_info:?}").unwrap();
     exit_qemu(QemuExitCode::Success);
 }
 
@@ -16,6 +16,6 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
 #[panic_handler]
 #[cfg(not(test))]
 fn panic(info: &core::panic::PanicInfo) -> ! {
-    let _ = writeln!(serial(), "PANIC: {}", info);
+    let _ = writeln!(serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/config_file/src/bin/basic_boot_broken_config_file.rs b/tests/test_kernels/config_file/src/bin/basic_boot_broken_config_file.rs
index d6401dc7..5232aa80 100644
--- a/tests/test_kernels/config_file/src/bin/basic_boot_broken_config_file.rs
+++ b/tests/test_kernels/config_file/src/bin/basic_boot_broken_config_file.rs
@@ -8,7 +8,7 @@ use test_kernel_config_file::{exit_qemu, serial, QemuExitCode};
 entry_point!(kernel_main);
 
 fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
-    writeln!(serial(), "Entered kernel with boot info: {:?}", boot_info).unwrap();
+    writeln!(serial(), "Entered kernel with boot info: {boot_info:?}").unwrap();
     exit_qemu(QemuExitCode::Success);
 }
 
@@ -16,6 +16,6 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
 #[panic_handler]
 #[cfg(not(test))]
 fn panic(info: &core::panic::PanicInfo) -> ! {
-    let _ = writeln!(serial(), "PANIC: {}", info);
+    let _ = writeln!(serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/default_settings/src/bin/basic_boot.rs b/tests/test_kernels/default_settings/src/bin/basic_boot.rs
index 8924e1c0..e2b7cc0b 100644
--- a/tests/test_kernels/default_settings/src/bin/basic_boot.rs
+++ b/tests/test_kernels/default_settings/src/bin/basic_boot.rs
@@ -8,7 +8,7 @@ use test_kernel_default_settings::{exit_qemu, serial, QemuExitCode};
 entry_point!(kernel_main);
 
 fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
-    writeln!(serial(), "Entered kernel with boot info: {:?}", boot_info).unwrap();
+    writeln!(serial(), "Entered kernel with boot info: {boot_info:?}").unwrap();
     exit_qemu(QemuExitCode::Success);
 }
 
@@ -16,6 +16,6 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
 #[panic_handler]
 #[cfg(not(test))]
 fn panic(info: &core::panic::PanicInfo) -> ! {
-    let _ = writeln!(serial(), "PANIC: {}", info);
+    let _ = writeln!(serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/default_settings/src/bin/check_boot_info.rs b/tests/test_kernels/default_settings/src/bin/check_boot_info.rs
index df1721d6..bc8fbad7 100644
--- a/tests/test_kernels/default_settings/src/bin/check_boot_info.rs
+++ b/tests/test_kernels/default_settings/src/bin/check_boot_info.rs
@@ -45,6 +45,6 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
 fn panic(info: &core::panic::PanicInfo) -> ! {
     use core::fmt::Write;
 
-    let _ = writeln!(test_kernel_default_settings::serial(), "PANIC: {}", info);
+    let _ = writeln!(test_kernel_default_settings::serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/higher_half/src/bin/check_boot_info.rs b/tests/test_kernels/higher_half/src/bin/check_boot_info.rs
index c35bb534..3cc96c3c 100644
--- a/tests/test_kernels/higher_half/src/bin/check_boot_info.rs
+++ b/tests/test_kernels/higher_half/src/bin/check_boot_info.rs
@@ -45,6 +45,6 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
 fn panic(info: &core::panic::PanicInfo) -> ! {
     use core::fmt::Write;
 
-    let _ = writeln!(test_kernel_higher_half::serial(), "PANIC: {}", info);
+    let _ = writeln!(test_kernel_higher_half::serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/higher_half/src/bin/verify_higher_half.rs b/tests/test_kernels/higher_half/src/bin/verify_higher_half.rs
index 930ff40d..79a1e964 100644
--- a/tests/test_kernels/higher_half/src/bin/verify_higher_half.rs
+++ b/tests/test_kernels/higher_half/src/bin/verify_higher_half.rs
@@ -34,6 +34,6 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
 fn panic(info: &core::panic::PanicInfo) -> ! {
     use core::fmt::Write;
 
-    let _ = writeln!(test_kernel_higher_half::serial(), "PANIC: {}", info);
+    let _ = writeln!(test_kernel_higher_half::serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/lto/src/bin/basic_boot.rs b/tests/test_kernels/lto/src/bin/basic_boot.rs
index 987f6781..bce7bf23 100644
--- a/tests/test_kernels/lto/src/bin/basic_boot.rs
+++ b/tests/test_kernels/lto/src/bin/basic_boot.rs
@@ -16,6 +16,6 @@ fn kernel_main(_boot_info: &'static mut BootInfo) -> ! {
 fn panic(info: &core::panic::PanicInfo) -> ! {
     use core::fmt::Write;
 
-    let _ = writeln!(test_kernel_lto::serial(), "PANIC: {}", info);
+    let _ = writeln!(test_kernel_lto::serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/map_phys_mem/src/bin/access_phys_mem.rs b/tests/test_kernels/map_phys_mem/src/bin/access_phys_mem.rs
index 2b906603..538362fb 100644
--- a/tests/test_kernels/map_phys_mem/src/bin/access_phys_mem.rs
+++ b/tests/test_kernels/map_phys_mem/src/bin/access_phys_mem.rs
@@ -22,6 +22,6 @@ fn panic(info: &core::panic::PanicInfo) -> ! {
     use core::fmt::Write;
     use test_kernel_map_phys_mem::serial;
 
-    let _ = writeln!(serial(), "PANIC: {}", info);
+    let _ = writeln!(serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/map_phys_mem/src/bin/check_boot_info.rs b/tests/test_kernels/map_phys_mem/src/bin/check_boot_info.rs
index 7fa487b7..5b3a8610 100644
--- a/tests/test_kernels/map_phys_mem/src/bin/check_boot_info.rs
+++ b/tests/test_kernels/map_phys_mem/src/bin/check_boot_info.rs
@@ -49,6 +49,6 @@ fn panic(info: &core::panic::PanicInfo) -> ! {
     use core::fmt::Write;
     use test_kernel_map_phys_mem::serial;
 
-    let _ = writeln!(serial(), "PANIC: {}", info);
+    let _ = writeln!(serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/pie/src/bin/basic_boot.rs b/tests/test_kernels/pie/src/bin/basic_boot.rs
index 2201d179..468dab12 100644
--- a/tests/test_kernels/pie/src/bin/basic_boot.rs
+++ b/tests/test_kernels/pie/src/bin/basic_boot.rs
@@ -16,6 +16,6 @@ fn kernel_main(_boot_info: &'static mut BootInfo) -> ! {
 fn panic(info: &core::panic::PanicInfo) -> ! {
     use core::fmt::Write;
 
-    let _ = writeln!(test_kernel_pie::serial(), "PANIC: {}", info);
+    let _ = writeln!(test_kernel_pie::serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/pie/src/bin/check_boot_info.rs b/tests/test_kernels/pie/src/bin/check_boot_info.rs
index a7b3a5e3..eba687e0 100644
--- a/tests/test_kernels/pie/src/bin/check_boot_info.rs
+++ b/tests/test_kernels/pie/src/bin/check_boot_info.rs
@@ -45,6 +45,6 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
 fn panic(info: &core::panic::PanicInfo) -> ! {
     use core::fmt::Write;
 
-    let _ = writeln!(test_kernel_pie::serial(), "PANIC: {}", info);
+    let _ = writeln!(test_kernel_pie::serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/pie/src/bin/global_variable.rs b/tests/test_kernels/pie/src/bin/global_variable.rs
index cba6338b..e349e7ed 100644
--- a/tests/test_kernels/pie/src/bin/global_variable.rs
+++ b/tests/test_kernels/pie/src/bin/global_variable.rs
@@ -31,6 +31,6 @@ fn kernel_main(_boot_info: &'static mut BootInfo) -> ! {
 fn panic(info: &core::panic::PanicInfo) -> ! {
     use core::fmt::Write;
 
-    let _ = writeln!(test_kernel_pie::serial(), "PANIC: {}", info);
+    let _ = writeln!(test_kernel_pie::serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/ramdisk/src/bin/basic_boot.rs b/tests/test_kernels/ramdisk/src/bin/basic_boot.rs
index 515cd22d..949c878b 100644
--- a/tests/test_kernels/ramdisk/src/bin/basic_boot.rs
+++ b/tests/test_kernels/ramdisk/src/bin/basic_boot.rs
@@ -16,6 +16,6 @@ fn kernel_main(_boot_info: &'static mut BootInfo) -> ! {
 fn panic(info: &core::panic::PanicInfo) -> ! {
     use core::fmt::Write;
 
-    let _ = writeln!(test_kernel_ramdisk::serial(), "PANIC: {}", info);
+    let _ = writeln!(test_kernel_ramdisk::serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }
diff --git a/tests/test_kernels/ramdisk/src/bin/ramdisk.rs b/tests/test_kernels/ramdisk/src/bin/ramdisk.rs
index d2bbda87..44fb5cd6 100644
--- a/tests/test_kernels/ramdisk/src/bin/ramdisk.rs
+++ b/tests/test_kernels/ramdisk/src/bin/ramdisk.rs
@@ -8,7 +8,7 @@ use test_kernel_ramdisk::{exit_qemu, serial, QemuExitCode, RAMDISK_CONTENTS};
 entry_point!(kernel_main);
 
 fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
-    writeln!(serial(), "Boot info: {:?}", boot_info).unwrap();
+    writeln!(serial(), "Boot info: {boot_info:?}").unwrap();
     assert!(boot_info.ramdisk_addr.into_option().is_some());
     assert_eq!(boot_info.ramdisk_len as usize, RAMDISK_CONTENTS.len());
     let actual_ramdisk = unsafe {
@@ -17,7 +17,7 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
             boot_info.ramdisk_len as usize,
         )
     };
-    writeln!(serial(), "Actual contents: {:?}", actual_ramdisk).unwrap();
+    writeln!(serial(), "Actual contents: {actual_ramdisk:?}").unwrap();
     assert_eq!(RAMDISK_CONTENTS, actual_ramdisk);
 
     exit_qemu(QemuExitCode::Success);
@@ -27,6 +27,6 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
 #[cfg(not(test))]
 #[panic_handler]
 fn panic(info: &core::panic::PanicInfo) -> ! {
-    let _ = writeln!(test_kernel_ramdisk::serial(), "PANIC: {}", info);
+    let _ = writeln!(test_kernel_ramdisk::serial(), "PANIC: {info}");
     exit_qemu(QemuExitCode::Failed);
 }

From 7fb15e6caf7f3c5dc79af513a44cce41b226b337 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juanjo=20Asensio=20Garc=C3=ADa?= <asengar2009@gmail.com>
Date: Fri, 27 Jan 2023 16:36:29 +0100
Subject: [PATCH 3/7] Fix clippy in common

---
 common/src/logger.rs | 2 +-
 common/src/serial.rs | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/common/src/logger.rs b/common/src/logger.rs
index 582e65e2..c2cfa54c 100644
--- a/common/src/logger.rs
+++ b/common/src/logger.rs
@@ -27,7 +27,7 @@ impl LockedLogger {
         };
 
         let serial = match serial_logger_status {
-            true => Some(Spinlock::new(SerialPort::new())),
+            true => Some(Spinlock::new(Default::default())),
             false => None,
         };
 
diff --git a/common/src/serial.rs b/common/src/serial.rs
index 1da346f2..8d350e18 100644
--- a/common/src/serial.rs
+++ b/common/src/serial.rs
@@ -4,8 +4,8 @@ pub struct SerialPort {
     port: uart_16550::SerialPort,
 }
 
-impl SerialPort {
-    pub fn new() -> Self {
+impl Default for SerialPort {
+    fn default() -> Self {
         let mut port = unsafe { uart_16550::SerialPort::new(0x3F8) };
         port.init();
         Self { port }

From 49ed52b444d613e90539108c969a4b10c1dbcd72 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juanjo=20Asensio=20Garc=C3=ADa?= <asengar2009@gmail.com>
Date: Fri, 27 Jan 2023 16:41:43 +0100
Subject: [PATCH 4/7] Fix clippy in bios

---
 bios/stage-2/src/main.rs | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/bios/stage-2/src/main.rs b/bios/stage-2/src/main.rs
index 137ca1a2..4e873699 100644
--- a/bios/stage-2/src/main.rs
+++ b/bios/stage-2/src/main.rs
@@ -102,11 +102,8 @@ fn start(disk_number: u16, partition_table_start: *const u8) -> ! {
     let kernel_page_size = (((kernel_len - 1) / 4096) + 1) as usize;
     let ramdisk_start = KERNEL_DST.wrapping_add(kernel_page_size * 4096);
     writeln!(screen::Writer, "Loading ramdisk...").unwrap();
-    let ramdisk_len = match try_load_file("ramdisk", ramdisk_start, &mut fs, &mut disk, disk_buffer)
-    {
-        Some(s) => s,
-        None => 0u64,
-    };
+    let ramdisk_len =
+        try_load_file("ramdisk", ramdisk_start, &mut fs, &mut disk, disk_buffer).unwrap_or(0u64);
 
     if ramdisk_len == 0 {
         writeln!(screen::Writer, "No ramdisk found, skipping.").unwrap();
@@ -114,16 +111,14 @@ fn start(disk_number: u16, partition_table_start: *const u8) -> ! {
         writeln!(screen::Writer, "Loaded ramdisk at {ramdisk_start:#p}").unwrap();
     }
     let config_file_start = ramdisk_start.wrapping_add(ramdisk_len.try_into().unwrap());
-    let config_file_len = match try_load_file(
+    let config_file_len = try_load_file(
         "config.json",
         config_file_start,
         &mut fs,
         &mut disk,
         disk_buffer,
-    ) {
-        Some(s) => s,
-        None => 0u64,
-    };
+    )
+    .unwrap_or(0);
 
     let memory_map = unsafe { memory_map::query_memory_map() }.unwrap();
     writeln!(screen::Writer, "{memory_map:x?}").unwrap();

From 63c9810735a20e5f5ac4d8d14689b552167073b4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juanjo=20Asensio=20Garc=C3=ADa?= <asengar2009@gmail.com>
Date: Fri, 27 Jan 2023 16:49:09 +0100
Subject: [PATCH 5/7] Fix clippy in uefi

---
 uefi/src/main.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/uefi/src/main.rs b/uefi/src/main.rs
index 47653ca1..56aea62c 100644
--- a/uefi/src/main.rs
+++ b/uefi/src/main.rs
@@ -187,8 +187,8 @@ fn main_inner(image: Handle, mut st: SystemTable<Boot>) -> Status {
                 .or_else(|| config_entries.find(|entry| matches!(entry.guid, cfg::ACPI_GUID)));
             rsdp.map(|entry| PhysAddr::new(entry.address as u64))
         },
-        ramdisk_addr: ramdisk_addr,
-        ramdisk_len: ramdisk_len,
+        ramdisk_addr,
+        ramdisk_len,
     };
 
     bootloader_x86_64_common::load_and_switch_to_kernel(
@@ -382,7 +382,7 @@ fn load_file_from_tftp_boot_server(
     let filename = CStr8::from_bytes_with_nul(name.as_bytes()).unwrap();
 
     // Determine the kernel file size.
-    let file_size = base_code.tftp_get_file_size(&server_ip, &filename).ok()?;
+    let file_size = base_code.tftp_get_file_size(&server_ip, filename).ok()?;
     let kernel_size = usize::try_from(file_size).expect("The file size should fit into usize");
 
     // Allocate some memory for the kernel file.
@@ -398,7 +398,7 @@ fn load_file_from_tftp_boot_server(
 
     // Load the kernel file.
     base_code
-        .tftp_read_file(&server_ip, &filename, Some(slice))
+        .tftp_read_file(&server_ip, filename, Some(slice))
         .expect("Failed to read kernel file from the TFTP boot server");
 
     Some(slice)

From aecd0a4dd9d0c2fd3b053cc4f15f1f28b60d5b48 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juanjo=20Asensio=20Garc=C3=ADa?= <asengar2009@gmail.com>
Date: Fri, 27 Jan 2023 17:08:17 +0100
Subject: [PATCH 6/7] Improve SerialPort constructor

---
 common/src/logger.rs | 2 +-
 common/src/serial.rs | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/common/src/logger.rs b/common/src/logger.rs
index c2cfa54c..a7491c58 100644
--- a/common/src/logger.rs
+++ b/common/src/logger.rs
@@ -27,7 +27,7 @@ impl LockedLogger {
         };
 
         let serial = match serial_logger_status {
-            true => Some(Spinlock::new(Default::default())),
+            true => Some(Spinlock::new(unsafe { SerialPort::init() })),
             false => None,
         };
 
diff --git a/common/src/serial.rs b/common/src/serial.rs
index 8d350e18..59f7b172 100644
--- a/common/src/serial.rs
+++ b/common/src/serial.rs
@@ -4,8 +4,8 @@ pub struct SerialPort {
     port: uart_16550::SerialPort,
 }
 
-impl Default for SerialPort {
-    fn default() -> Self {
+impl SerialPort {
+    pub unsafe fn init() -> Self {
         let mut port = unsafe { uart_16550::SerialPort::new(0x3F8) };
         port.init();
         Self { port }

From cfded08f7e8af7d62c4f9901a8de610dd80d1e5b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juanjo=20Asensio=20Garc=C3=ADa?=
 <101601871+asensio-project@users.noreply.github.com>
Date: Fri, 27 Jan 2023 17:21:04 +0100
Subject: [PATCH 7/7] Add docs for serial port

---
 common/src/serial.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/common/src/serial.rs b/common/src/serial.rs
index 59f7b172..1882e366 100644
--- a/common/src/serial.rs
+++ b/common/src/serial.rs
@@ -5,6 +5,9 @@ pub struct 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();