Do not use COM3 or COM4

src/arch/x86_64/device/serial.rs

@@ -13,8 +13,6 @@ pub static LPSS: Mutex<Option<&'static mut SerialPort<Mmio<u32>>>> = Mutex::new(
 pub unsafe fn init() {
     COM1.lock().init();
     COM2.lock().init();
-    COM3.lock().init();
-    COM4.lock().init();
 
     #[cfg(feature = "lpss_debug")]
     {

src/arch/x86_64/interrupt/irq.rs

@@ -2,7 +2,7 @@ use core::sync::atomic::{AtomicUsize, Ordering};
 
 use crate::context::timeout;
 use crate::device::pic;
-use crate::device::serial::{COM1, COM2, COM3, COM4};
+use crate::device::serial::{COM1, COM2};
 use crate::ipi::{ipi, IpiKind, IpiTarget};
 use crate::scheme::debug::debug_input;
 use crate::{context, ptrace, time};
@@ -78,9 +78,6 @@ interrupt!(com2, {
     while let Some(c) = COM2.lock().receive() {
         debug_input(c);
     }
-    while let Some(c) = COM4.lock().receive() {
-        debug_input(c);
-    }
     pic::MASTER.ack();
 });
 
@@ -88,9 +85,6 @@ interrupt!(com1, {
     while let Some(c) = COM1.lock().receive() {
         debug_input(c);
     }
-    while let Some(c) = COM3.lock().receive() {
-        debug_input(c);
-    }
     pic::MASTER.ack();
 });