diff --git a/crate/bit-allocator/src/lib.rs b/crate/bit-allocator/src/lib.rs
index 28f1d5d..325e74e 100644
--- a/crate/bit-allocator/src/lib.rs
+++ b/crate/bit-allocator/src/lib.rs
@@ -134,6 +134,12 @@ fn log2(x: u16) -> usize {
 #[inline(always)]
 #[cfg(not(target_arch = "x86_64"))]
 fn log2(x: u16) -> usize {
+    log2_naive(x)
+}
+
+#[cfg(not(target_arch = "x86_64"))]
+#[inline(always)]
+fn log2_naive(mut x: u16) -> usize {
     //a naive implement
     assert_ne!(x, 0);
     let mut pos = -1;
@@ -148,6 +154,7 @@ fn log2(x: u16) -> usize {
 mod tests {
     use super::*;
 
+    #[cfg(not(target_arch = "x86_64"))]
     #[test]
     fn log2_() {
         for x in 1..=0xffff {
diff --git a/kernel/src/arch/aarch64/board/raspi3/irq.rs b/kernel/src/arch/aarch64/board/raspi3/irq.rs
index d8730dc..9575e29 100644
--- a/kernel/src/arch/aarch64/board/raspi3/irq.rs
+++ b/kernel/src/arch/aarch64/board/raspi3/irq.rs
@@ -1,6 +1,5 @@
 use crate::arch::interrupt::TrapFrame;
 use bcm2837::interrupt::Controller;
-use log::*;
 
 pub use bcm2837::interrupt::Interrupt;
 
diff --git a/kernel/src/arch/aarch64/memory.rs b/kernel/src/arch/aarch64/memory.rs
index 1ba7a67..13996fe 100644
--- a/kernel/src/arch/aarch64/memory.rs
+++ b/kernel/src/arch/aarch64/memory.rs
@@ -5,7 +5,7 @@ use ucore_memory::PAGE_SIZE;
 use atags::atags::Atags;
 use aarch64::{barrier, regs::*, addr::*};
 use aarch64::paging::{PhysFrame as Frame, memory_attribute::*};
-use crate::memory::{FRAME_ALLOCATOR, init_heap, MemoryArea, MemoryAttr, MemorySet, Linear};
+use crate::memory::{FRAME_ALLOCATOR, init_heap, MemoryAttr, MemorySet, Linear};
 
 /// Memory initialization.
 pub fn init() {
diff --git a/kernel/src/arch/aarch64/paging.rs b/kernel/src/arch/aarch64/paging.rs
index 8173681..8bfee47 100644
--- a/kernel/src/arch/aarch64/paging.rs
+++ b/kernel/src/arch/aarch64/paging.rs
@@ -1,8 +1,6 @@
 //! Page table implementations for aarch64.
-use ucore_memory::memory_set::*;
-use ucore_memory::PAGE_SIZE;
 use ucore_memory::paging::*;
-use aarch64::asm::{tlb_invalidate, tlb_invalidate_all, flush_icache_all, ttbr_el1_read, ttbr_el1_write};
+use aarch64::asm::{tlb_invalidate, tlb_invalidate_all, ttbr_el1_read, ttbr_el1_write};
 use aarch64::{PhysAddr, VirtAddr};
 use aarch64::paging::{Mapper, PageTable as Aarch64PageTable, PageTableEntry, PageTableFlags as EF, RecursivePageTable};
 use aarch64::paging::{FrameAllocator, FrameDeallocator, Page, PhysFrame as Frame, Size4KiB, Size2MiB, Size1GiB};