diff --git a/kernel/src/arch/riscv/vspace/utils.rs b/kernel/src/arch/riscv/vspace/utils.rs
index 2962161..0790547 100644
--- a/kernel/src/arch/riscv/vspace/utils.rs
+++ b/kernel/src/arch/riscv/vspace/utils.rs
@@ -96,14 +96,40 @@ pub unsafe fn setup_kernel_paging<const N: usize>(allocator: &mut RamBlock<N>) {
 
     // map 4 GiB physical memory
     // TODO: walk fdt to get all memory region?
-    for addr in (0..(3 * GIB - 1 + GIB)).step_by(TableLevel::Level1.level_size()) {
-        let phys_addr = PhysAddr(addr);
-        map(
-            mmap_phys_to_virt(phys_addr),
-            phys_addr,
-            MapAttr::READABLE | MapAttr::WRITABLE,
-            TableLevel::Level1,
-        );
+    {
+        #[cfg(feature = "legacy")]
+        let level = TableLevel::Level1;
+        #[cfg(not(feature = "legacy"))]
+        let level = TableLevel::Level2;
+
+        let addr_end = PhysAddr(3 * GIB - 1 + GIB);
+        let mut phys_addr = PhysAddr(0);
+        let mut map_level = level;
+
+        while phys_addr < addr_end {
+            let ok = map(
+                kernel_phys_to_virt(phys_addr),
+                phys_addr,
+                MapAttr::READABLE | MapAttr::WRITABLE,
+                map_level,
+            );
+
+            if ok || map_level.next().is_none() {
+                // map success or reach the end, move to next region
+                phys_addr += map_level.level_size();
+
+                // check whether we could raise the level
+                if let Some(prv) = map_level.previous()
+                    && prv.is_aligned(phys_addr)
+                {
+                    map_level = prv;
+                }
+                continue;
+            }
+
+            // already mapped, try smaller level
+            map_level = map_level.next().unwrap();
+        }
     }
 
     riscv::register::satp::set(riscv::register::satp::Mode::Sv39, 0, root_pt.to_ppn());
diff --git a/kernel/src/vspace/paging/table.rs b/kernel/src/vspace/paging/table.rs
index b01d702..3d1993c 100644
--- a/kernel/src/vspace/paging/table.rs
+++ b/kernel/src/vspace/paging/table.rs
@@ -25,6 +25,18 @@ impl TableLevel {
             Self::Level4 => Some(Self::Level3),
         }
     }
+
+    pub fn previous(&self) -> Option<Self> {
+        match self {
+            Self::Level0 => Some(Self::Level1),
+            Self::Level1 => Some(Self::Level2),
+            Self::Level2 => Some(Self::Level3),
+            #[cfg(not(feature = "legacy"))]
+            Self::Level3 => Some(Self::Level4),
+            #[cfg(not(feature = "legacy"))]
+            Self::Level4 => None,
+        }
+    }
 }
 
 #[derive(Debug)]