diff --git a/abstract-machine/am/src/x86/nemu/cte.c b/abstract-machine/am/src/x86/nemu/cte.c
index 5d7993b7..e52647f3 100644
--- a/abstract-machine/am/src/x86/nemu/cte.c
+++ b/abstract-machine/am/src/x86/nemu/cte.c
@@ -33,6 +33,8 @@ Context* __am_irq_handle(Context* c) {
             ev.event = EVENT_IRQ_TIMER;
             break;
         case 0x80:
+            if(c->eax == 9)
+                printf("Int trap, a[1] == %x\n", c->ebx);
             ev.event = EVENT_SYSCALL;
             break;
         case 0x81:
diff --git a/nanos-lite/src/mm.c b/nanos-lite/src/mm.c
index dca792b7..5cc5fe4d 100644
--- a/nanos-lite/src/mm.c
+++ b/nanos-lite/src/mm.c
@@ -29,7 +29,7 @@ void free_page(void *p) {
 // if brk exceed current->max_brk, we allocate new_page()
 void map(AddrSpace* as, void* va, void* pa, int prot);
 int mm_brk(uintptr_t brk) {
-    printf("brk == %x\n", brk);
+    printf("mm_brk, brk == %x\n", brk);
     printf("current->max_brk == %x\n", current->max_brk);
     if(brk > current->max_brk){
         uintptr_t vaddr = current->max_brk;
diff --git a/nanos-lite/src/syscall.c b/nanos-lite/src/syscall.c
index 04099051..8fc58735 100644
--- a/nanos-lite/src/syscall.c
+++ b/nanos-lite/src/syscall.c
@@ -41,6 +41,7 @@ void do_syscall(Context* c) {
     }
     case SYS_brk:
         //c->GPRx = 0;
+        printf("nanos, brk == %x\n", a[1]);
         c->GPRx = mm_brk(a[1]);
         break;
     case SYS_open:
diff --git a/navy-apps/libs/libos/src/syscall.c b/navy-apps/libs/libos/src/syscall.c
index 4d733d0d..a5da2d50 100644
--- a/navy-apps/libs/libos/src/syscall.c
+++ b/navy-apps/libs/libos/src/syscall.c
@@ -3,6 +3,7 @@
 #include <errno.h>
 #include <assert.h>
 #include <unistd.h>
+#include <string.h>
 #include <sys/stat.h>
 #include <sys/time.h>
 #include "syscall.h"
@@ -48,6 +49,14 @@
 #endif
 
 intptr_t _syscall_(intptr_t type, intptr_t a0, intptr_t a1, intptr_t a2) {
+    if(type == 9){
+        char tmp[69] = {};
+        sprintf(tmp, "navy, brk _syscall_, brk == %p\n", (char*)a0);
+        write(1, tmp, sizeof(tmp));
+        memset(tmp, 0, 69);
+        sprintf(tmp, "navy, brk _syscall_, brk == %lu\n", a0);
+        write(1, tmp, sizeof(tmp));
+    }
     register intptr_t _gpr1 asm(GPR1) = type;
     register intptr_t _gpr2 asm(GPR2) = a0;
     register intptr_t _gpr3 asm(GPR3) = a1;
@@ -76,14 +85,30 @@ int _write(int fd, void* buf, size_t count) {
 extern char  _end;
 static char* proc_brk = &_end;
 void* _sbrk(intptr_t increment) {
+    char tmp[69] = {};
+    sprintf(tmp, "navy, proc_brk == %p\n", proc_brk);
+    write(1, tmp, sizeof(tmp));
+    memset(tmp, 0, 69);
+    sprintf(tmp, "navy, increment == %p\n", (char*)increment);
+    write(1, tmp, sizeof(tmp));
+    memset(tmp, 0, 69);
+    sprintf(tmp, "navy, increment == %lu\n", increment);
+    write(1, tmp, sizeof(tmp));
+    memset(tmp, 0, 69);
     intptr_t pre_brk = (intptr_t)proc_brk;
     intptr_t req_brk = (intptr_t)proc_brk + increment;
+    sprintf(tmp, "navy, req_brk == %p\n", (char*)req_brk);
+    write(1, tmp, sizeof(tmp));
+    memset(tmp, 0, 69);
+    sprintf(tmp, "navy, req_brk == %lu\n", req_brk);
+    write(1, tmp, sizeof(tmp));
+    memset(tmp, 0, 69);
     // Attention for the argument passed to the system call.
     if((char *)req_brk < &_end){
         return (void*)-1; 
     }
 
-    if(!_syscall_(SYS_brk, (intptr_t)&req_brk, 0, 0)){
+    if(!_syscall_(SYS_brk, (intptr_t)req_brk, 0, 0)){
         proc_brk += increment;
         return (void*)pre_brk;
     } else {
diff --git a/nemu/src/device/intr.c b/nemu/src/device/intr.c
index 223fc4db..a312605e 100644
--- a/nemu/src/device/intr.c
+++ b/nemu/src/device/intr.c
@@ -1,5 +1,5 @@
 #include <isa.h>
 
 void dev_raise_intr() {
-    //cpu.INTR = true;
+    cpu.INTR = true;
 }
diff --git a/nemu/tools/gen-expr/gen-expr.c b/nemu/tools/gen-expr/gen-expr.c
index 5f14356b..228401d1 100644
--- a/nemu/tools/gen-expr/gen-expr.c
+++ b/nemu/tools/gen-expr/gen-expr.c
@@ -79,9 +79,12 @@ static inline void gen_rand_op() {
              gen_rand_expr();
              break;
          }
-     } else {
-         gen_rand_num();
-     }
+     } 
+     /*
+      *else {
+      *    gen_rand_num();
+      *}
+      */
      buf[strlen(buf)] = '\0';
  }