diff --git a/Cargo.lock b/Cargo.lock
index 7e6945bb..c2ab1e66 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -54,12 +54,6 @@ dependencies = [
  "spinning_top",
 ]
 
-[[package]]
-name = "array-init"
-version = "2.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3d62b7694a562cdf5a74227903507c56ab2cc8bdd1f781ed5cb4cf9c9f810bfc"
-
 [[package]]
 name = "arrayvec"
 version = "0.5.2"
@@ -1050,7 +1044,6 @@ dependencies = [
  "acpi",
  "align_ext",
  "aml",
- "array-init",
  "bit_field",
  "bitflags 1.3.2",
  "bitvec",
diff --git a/ostd/Cargo.toml b/ostd/Cargo.toml
index 6fa985a1..edbbbd5b 100644
--- a/ostd/Cargo.toml
+++ b/ostd/Cargo.toml
@@ -16,7 +16,6 @@ targets = ["x86_64-unknown-none"]
 
 [dependencies]
 align_ext = { path = "libs/align_ext", version = "0.1.0" }
-array-init = "2.0"
 bit_field = "0.10.1"
 buddy_system_allocator = "0.9.0"
 bitflags = "1.3"
diff --git a/ostd/src/boot/smp.rs b/ostd/src/boot/smp.rs
index b442cd97..33a52daa 100644
--- a/ostd/src/boot/smp.rs
+++ b/ostd/src/boot/smp.rs
@@ -15,7 +15,6 @@ use crate::{
         page::{self, meta::KernelMeta, ContPages},
         PAGE_SIZE,
     },
-    trap,
 };
 
 pub(crate) static AP_BOOT_INFO: Once<ApBootInfo> = Once::new();
@@ -120,7 +119,10 @@ fn ap_early_entry(local_apic_id: u32) -> ! {
         cpu::set_this_cpu_id(local_apic_id);
     }
 
-    trap::init();
+    // SAFETY: this function is only called once on this AP.
+    unsafe {
+        trapframe::init();
+    }
     crate::arch::irq::enable_local();
 
     // Mark the AP as started.
diff --git a/ostd/src/lib.rs b/ostd/src/lib.rs
index ff7a8096..b35bb245 100644
--- a/ostd/src/lib.rs
+++ b/ostd/src/lib.rs
@@ -86,7 +86,9 @@ pub unsafe fn init() {
     mm::kspace::init_kernel_page_table(mm::init_page_meta());
     mm::misc_init();
 
-    trap::init();
+    trapframe::init();
+    // SAFETY: This function is called only once in the entire system.
+    unsafe { trap::softirq::init() };
     arch::init_on_bsp();
 
     bus::init();
diff --git a/ostd/src/trap/mod.rs b/ostd/src/trap/mod.rs
index 358cf045..3c99972b 100644
--- a/ostd/src/trap/mod.rs
+++ b/ostd/src/trap/mod.rs
@@ -12,10 +12,3 @@ pub use trapframe::TrapFrame;
 
 pub(crate) use self::handler::call_irq_callback_functions;
 pub use self::irq::{disable_local, DisabledLocalIrqGuard, IrqCallbackFunction, IrqLine};
-
-pub(crate) fn init() {
-    unsafe {
-        trapframe::init();
-    }
-    softirq::init();
-}
diff --git a/ostd/src/trap/softirq.rs b/ostd/src/trap/softirq.rs
index 3d9a136c..6efa8ec5 100644
--- a/ostd/src/trap/softirq.rs
+++ b/ostd/src/trap/softirq.rs
@@ -95,9 +95,14 @@ impl SoftIrqLine {
 /// A slice that stores the [`SoftIrqLine`]s, whose ID is equal to its offset in the slice.
 static LINES: Once<[SoftIrqLine; SoftIrqLine::NR_LINES as usize]> = Once::new();
 
-pub(super) fn init() {
+/// Initializes the softirq lines.
+///
+/// # Safety
+///
+/// This function must be called only once.
+pub unsafe fn init() {
     let lines: [SoftIrqLine; SoftIrqLine::NR_LINES as usize] =
-        array_init::array_init(|i| SoftIrqLine::new(i as u8));
+        core::array::from_fn(|i| SoftIrqLine::new(i as u8));
     LINES.call_once(|| lines);
 }