diff --git a/kernel/Cargo.lock b/kernel/Cargo.lock
index 9f3cb58..6c6b307 100644
--- a/kernel/Cargo.lock
+++ b/kernel/Cargo.lock
@@ -307,7 +307,7 @@ dependencies = [
 [[package]]
 name = "riscv"
 version = "0.3.0"
-source = "git+https://github.com/riscv-and-rust-and-decaf/riscv#f6f475e35b36717cf4455e298e4468773a57eb84"
+source = "git+https://github.com/riscv-and-rust-and-decaf/riscv#ac09fc675387998df9874349fd9794aced81185c"
 dependencies = [
  "bare-metal 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "bit_field 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/kernel/Cargo.toml b/kernel/Cargo.toml
index b02f003..36ad8af 100644
--- a/kernel/Cargo.toml
+++ b/kernel/Cargo.toml
@@ -19,6 +19,9 @@ authors = [
 no_mmu = []
 # Kernel in M-mode (for riscv)
 m_mode = ["no_mmu"]
+# Page table sv39 or sv48 (for riscv64)
+sv39 = []
+board_u540 = ["sv39"]
 # (for aarch64 RaspberryPi3)
 nographic = []
 board_raspi3 = ["bcm2837"]
diff --git a/kernel/Makefile b/kernel/Makefile
index b344fcb..fbe27b6 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -124,7 +124,12 @@ endif
 
 ifdef m_mode
 features += no_mmu m_mode
-bbl_m_mode := --enable-boot-machine
+riscv_pk_args := --enable-boot-machine
+endif
+
+ifeq ($(board), u540)
+features += sv39
+riscv_pk_args += --enable-sv39
 endif
 
 ifneq ($(board), none)
@@ -210,7 +215,7 @@ ifeq ($(arch), riscv32)
 	@mkdir -p target/$(target)/bbl && \
 	cd target/$(target)/bbl && \
 	$(bbl_path)/configure \
-		$(bbl_m_mode) \
+		$(riscv_pk_args) \
 		--with-arch=rv32imac \
 		--disable-fp-emulation \
 		--host=riscv64-unknown-elf \
@@ -224,7 +229,7 @@ else
 	@mkdir -p target/$(target)/bbl && \
 	cd target/$(target)/bbl && \
 	$(bbl_path)/configure \
-		$(bbl_m_mode) \
+		$(riscv_pk_args) \
 		--with-arch=rv64imac \
 		--disable-fp-emulation \
 		--host=riscv64-unknown-elf \
diff --git a/kernel/build-rv64 b/kernel/build-rv64
index eb91e79..b4d467f 100755
--- a/kernel/build-rv64
+++ b/kernel/build-rv64
@@ -553,7 +553,7 @@ fi
 CNAME=riscv
 if ! [[ -f ${OUTDIR}/${CNAME}.o ]]
 then
-rustc --crate-name riscv $CARGO_PATH/git/checkouts/riscv-1e845b622ce46f1d/f6f475e*/src/lib.rs \
+rustc --crate-name riscv $CARGO_PATH/git/checkouts/riscv-1e845b622ce46f1d/ac09fc6*/src/lib.rs \
     --color always --crate-type lib --emit=metadata,llvm-bc \
     -C opt-level=1 \
     -C debuginfo=2 \
@@ -605,6 +605,9 @@ CNAME=rcore
 if [[ ${board} = k210 ]]; then
     export UCORE_FEATURE_ARGS='--cfg feature="m_mode" --cfg feature="no_mmu" --cfg feature="board_k210"'
     cp src/arch/riscv32/board/k210/linker.ld src/arch/riscv32/boot/linker64.ld
+elif [[ ${board} = u540 ]]; then
+    export UCORE_FEATURE_ARGS='--cfg feature="sv39" --cfg feature="board_u540"'
+    cp src/arch/riscv32/board/u540/linker.ld src/arch/riscv32/boot/linker64.ld
 else
     cp src/arch/riscv32/board/u540/linker.ld src/arch/riscv32/boot/linker64.ld
 fi
diff --git a/kernel/src/arch/riscv32/paging.rs b/kernel/src/arch/riscv32/paging.rs
index adf71ad..86a2380 100644
--- a/kernel/src/arch/riscv32/paging.rs
+++ b/kernel/src/arch/riscv32/paging.rs
@@ -3,7 +3,7 @@ use crate::consts::RECURSIVE_INDEX;
 use crate::memory::{active_table, alloc_frame, dealloc_frame};
 use riscv::addr::*;
 use riscv::asm::{sfence_vma, sfence_vma_all};
-use riscv::paging::{Mapper, PageTable as RvPageTable, PageTableEntry, PageTableFlags as EF, RecursivePageTable};
+use riscv::paging::{Mapper, PageTable as RvPageTable, PageTableEntry, PageTableFlags as EF, RecursivePageTable, PageTableType};
 use riscv::paging::{FrameAllocator, FrameDeallocator};
 use riscv::register::satp;
 use rcore_memory::paging::*;
@@ -58,7 +58,14 @@ impl PageTableExt for ActivePageTable {}
 const ROOT_PAGE_TABLE: *mut RvPageTable =
     ((RECURSIVE_INDEX     << 12 << 10) |
      ((RECURSIVE_INDEX+1) << 12)) as *mut RvPageTable;
-#[cfg(target_arch = "riscv64")]
+#[cfg(all(target_arch = "riscv64", feature = "sv39"))]
+const ROOT_PAGE_TABLE: *mut RvPageTable =
+    ((0xFFFF_0000_0000_0000) |
+     (0o777               << 12 << 9 << 9 << 9) |
+     (RECURSIVE_INDEX     << 12 << 9 << 9) |
+     (RECURSIVE_INDEX     << 12 << 9) |
+     ((RECURSIVE_INDEX+1) << 12)) as *mut RvPageTable;
+#[cfg(all(target_arch = "riscv64", not(feature = "sv39")))]
 const ROOT_PAGE_TABLE: *mut RvPageTable =
     ((0xFFFF_0000_0000_0000) |
      (RECURSIVE_INDEX     << 12 << 9 << 9 << 9) |
@@ -67,12 +74,24 @@ const ROOT_PAGE_TABLE: *mut RvPageTable =
      ((RECURSIVE_INDEX+1) << 12)) as *mut RvPageTable;
 
 impl ActivePageTable {
+    #[cfg(target_arch = "riscv32")]
     pub unsafe fn new() -> Self {
         ActivePageTable(
             RecursivePageTable::new(&mut *ROOT_PAGE_TABLE).unwrap(),
             ::core::mem::uninitialized()
         )
     }
+    #[cfg(target_arch = "riscv64")]
+    pub unsafe fn new() -> Self {
+        #[cfg(feature = "sv39")]
+        let type_ = PageTableType::Sv39;
+        #[cfg(not(feature = "sv39"))]
+        let type_ = PageTableType::Sv48;
+        ActivePageTable(
+            RecursivePageTable::new(&mut *ROOT_PAGE_TABLE, type_).unwrap(),
+            ::core::mem::uninitialized()
+        )
+    }
 }
 
 /// implementation for the Entry trait in /crate/memory/src/paging/mod.rs
@@ -177,7 +196,10 @@ impl InactivePageTable for InactivePageTable0 {
         use bit_field::BitField;
         let mut satp = self.root_frame.number();
         satp.set_bits(44..60, 0);  // AS is 0
-        satp.set_bits(60..64, satp::Mode::Sv48 as usize);  // Mode is Sv48
+        #[cfg(feature = "sv39")]
+        satp.set_bits(60..64, satp::Mode::Sv39 as usize);
+        #[cfg(not(feature = "sv39"))]
+        satp.set_bits(60..64, satp::Mode::Sv48 as usize);
         satp
     }
 
diff --git a/riscv-pk b/riscv-pk
index e309fff..e216edb 160000
--- a/riscv-pk
+++ b/riscv-pk
@@ -1 +1 @@
-Subproject commit e309fff977870e7596f87788c891dfd393fd5296
+Subproject commit e216edbf9898b5bdb5c3b2c1fe6c0df00c8a7ba9