diff --git a/include/common.h b/include/common.h
index 89721c25941c34853684585de7b022e2ea82470d..52b03ef20115e9bf4956cb81514b182c97d6eb74 100644
--- a/include/common.h
+++ b/include/common.h
@@ -2,7 +2,7 @@
 #define __COMMON_H__
 
 #define DEBUG
-#define DIFF_TEST
+//#define DIFF_TEST
 
 #define ISA64
 
diff --git a/src/isa/riscv64/diff-test.c b/src/isa/riscv64/diff-test.c
index c3401d76a8cbb68034bf39f2a2a25de64f15be18..d0e26cf5c0986a00c58fa221b92e9a32238da753 100644
--- a/src/isa/riscv64/diff-test.c
+++ b/src/isa/riscv64/diff-test.c
@@ -2,6 +2,14 @@
 #include "monitor/diff-test.h"
 
 bool isa_difftest_checkregs(CPU_state *ref_r, vaddr_t pc) {
+  /*
+  int i;
+  for (i = 0; i < sizeof(cpu.gpr) / sizeof(cpu.gpr[0]); i ++) {
+    if (((uint64_t)cpu.gpr[i]._64) > ((uint64_t)0xffffffff)) {
+      printf("!!-0x%lx, 0x%lx\n", ref_r->gpr[i]._64, cpu.gpr[i]._64);
+    }
+  }*/
+  
   if (memcmp(&cpu, ref_r, DIFFTEST_REG_SIZE)) {
     int i;
     for (i = 0; i < sizeof(cpu.gpr) / sizeof(cpu.gpr[0]); i ++) {
diff --git a/src/isa/riscv64/exec/compute.c b/src/isa/riscv64/exec/compute.c
index 5d370ad13f9b3865c39fb6c500876d78ba7d0f5a..4162edd273b27f11eb97f9f36c3ec01ec414a659 100644
--- a/src/isa/riscv64/exec/compute.c
+++ b/src/isa/riscv64/exec/compute.c
@@ -93,6 +93,7 @@ make_EHelper(auipc) {
 }
 
 make_EHelper(lui) {
+  rtl_sext(&id_src->val, &id_src->val, 4);
   rtl_sr(id_dest->reg, &id_src->val, 4);
 
   print_asm_template2(lui);
diff --git a/src/monitor/diff-test/diff-test.c b/src/monitor/diff-test/diff-test.c
index 89b3aff906cfc5ae286830a47fd50ef418522318..76ae5d95f9ce845fd100891947e4297bbdc88d0e 100644
--- a/src/monitor/diff-test/diff-test.c
+++ b/src/monitor/diff-test/diff-test.c
@@ -67,7 +67,6 @@ void init_difftest(char *ref_so_file, long img_size) {
       "If it is not necessary, you can turn it off in include/common.h.", ref_so_file);
 
   ref_difftest_init();
-  Log("Init done\n");
   ref_difftest_memcpy_from_dut(PC_START, guest_to_host(IMAGE_START), img_size);
   ref_difftest_setregs(&cpu);
 }
diff --git a/tools/qemu-diff/src/diff-test.c b/tools/qemu-diff/src/diff-test.c
index f4d44dd7956aa6d6288839678977cdb249789f4e..1c214ee2c59b2ebf31e0cc7604026160c361e55b 100644
--- a/tools/qemu-diff/src/diff-test.c
+++ b/tools/qemu-diff/src/diff-test.c
@@ -31,9 +31,7 @@ void difftest_setregs(const void *r) {
 }
 
 void difftest_exec(uint64_t n) {
-  while (n --) { 
-    gdb_si();
-  }
+  while (n --) gdb_si();
 }
 
 void difftest_init(void) {
diff --git a/tools/qemu-diff/src/gdb-host.c b/tools/qemu-diff/src/gdb-host.c
index 65c97569d64a3ae8079cdb96fb078ecd0af68b93..7e30617716582a076fd51a3f9ee2f79753ac5821 100644
--- a/tools/qemu-diff/src/gdb-host.c
+++ b/tools/qemu-diff/src/gdb-host.c
@@ -90,7 +90,7 @@ bool gdb_setregs(union isa_gdb_regs *r) {
 }
 
 bool gdb_si(void) {
-  
+
   char buf[] = "vCont;s:1";
   gdb_send(conn, (const uint8_t *)buf, strlen(buf));
   size_t size;
diff --git a/tools/qemu-diff/src/isa/riscv64/include/isa.h b/tools/qemu-diff/src/isa/riscv64/include/isa.h
index a1a2e827464603cf041f96b4bf2b1c8c3df5ef83..3d13d80d5ea909aef6cedc2af66f4e64906a9c20 100644
--- a/tools/qemu-diff/src/isa/riscv64/include/isa.h
+++ b/tools/qemu-diff/src/isa/riscv64/include/isa.h
@@ -8,8 +8,8 @@
 
 union isa_gdb_regs {
   struct {
-    uint32_t gpr[32];
-    uint32_t pc;
+    uint64_t gpr[32];
+    uint64_t pc;
   };
   struct {
     uint32_t array[77];
diff --git a/tools/qemu-diff/src/isa/riscv64/init.c b/tools/qemu-diff/src/isa/riscv64/init.c
index 651f58ce285f1e05610084a02ae818ca4fc877a2..bff7e7a7202159abbc86bc86cf9a6110b3cc7334 100644
--- a/tools/qemu-diff/src/isa/riscv64/init.c
+++ b/tools/qemu-diff/src/isa/riscv64/init.c
@@ -6,7 +6,8 @@ bool gdb_setregs(union isa_gdb_regs *);
 void difftest_exec(uint64_t n);
 
 static uint32_t initcode[] = {
-  0x800006b7,  // lui a3,0x8000
+  //0x800006b7,  // lui a3,0x8000
+  0x00000697,  // auipc a3, 0x0
   0x03c68693,  // addi a3,a3,0x3c # 800003c
   0x30569073,  // csrw mtvec,a3
 
@@ -49,16 +50,15 @@ void init_isa(void) {
 
   gdb_getregs(&r);
 
-  /*
-  int i;
+  
+  /*int i;
   printf("print regs:\n");
   for (i = 0; i < 32; i++) {
-    printf("0x%x\n", r.gpr[i]);
+    printf("0x%lx\n", r.gpr[i]);
   }
-  printf("0x%x\nend print\n", r.pc);
+  printf("0x%lx\nend print\n", r.pc);
   fflush(stdout);*/
 
   // execute enough instructions
-  difftest_exec(19);
-
+  difftest_exec(20);
 }