diff --git a/SPEC.md b/SPEC.md
index f65b7b3d..990c9840 100644
--- a/SPEC.md
+++ b/SPEC.md
@@ -46,7 +46,8 @@
   * `_EVENT_BUS_ERROR`:总线错误(cause: 产生错误的地址)
   * `_EVENT_NUMERIC`:数值错误(无cause)
   * `_EVENT_TRAP`:内核态自陷(无cause)
-  * `_EVENT_SYSCALL`: 系统调用(无cause)，系统调用参数将`_RegSet`转换为`intptr_t*`后按次序排列。第一个参数为返回值。
+  * `_EVENT_SYSCALL`: 系统调用(无cause)
+* `SYSCALL_ARGx(reg);`从寄存器现场中获取系统调用的参数。其中`x`为`1`~`4`。
 * `_RegSet *_make(_Area kstack, void *entry, void *arg);`创建一个内核上下文,参数arg。
 * `void _trap();`在内核态自陷。线程需要睡眠/让出CPU时使用。
 * `int _istatus(int enable);`设置中断状态(enable非0时打开)。返回设置前的中断状态(0/1)。
diff --git a/am/arch/x86-nemu/include/arch.h b/am/arch/x86-nemu/include/arch.h
index 70ba1d4d..1bb1fc40 100644
--- a/am/arch/x86-nemu/include/arch.h
+++ b/am/arch/x86-nemu/include/arch.h
@@ -16,6 +16,10 @@ struct _RegSet {
 };
 
 typedef struct _RegSet TrapFrame;
+#define SYSCALL_ARG1(r) ((r)->eax)
+#define SYSCALL_ARG2(r) ((r)->ebx)
+#define SYSCALL_ARG3(r) ((r)->ecx)
+#define SYSCALL_ARG4(r) ((r)->edx)
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/am/arch/x86-nemu/src/asye.c b/am/arch/x86-nemu/src/asye.c
index 272ef848..065a35a1 100644
--- a/am/arch/x86-nemu/src/asye.c
+++ b/am/arch/x86-nemu/src/asye.c
@@ -12,27 +12,14 @@ uintptr_t irq_handle(_RegSet *r) {
   _RegSet *next = r;
   if (H) {
     _Event ev;
-    intptr_t args[4];
     switch (r->irq) {
       case 32: ev.event = _EVENT_IRQ_TIME; break;
-      case 0x80: {
-        ev.event = _EVENT_SYSCALL;
-        args[0] = r->eax;
-        args[1] = r->ebx;
-        args[2] = r->ecx;
-        args[3] = r->edx;
-        ev.cause = (intptr_t)args;
-        break;
-      }
+      case 0x80: ev.event = _EVENT_SYSCALL; break;
       case 0x81: ev.event = _EVENT_TRAP; break;
       default: ev.event = _EVENT_ERROR; break;
     }
 
     next = H(ev, r);
-    if (ev.event == _EVENT_SYSCALL) {
-      r->eax = args[0];
-    }
-
     if (next == NULL) {
       next = r;
     }
diff --git a/apps/nanos-lite/src/irq.c b/apps/nanos-lite/src/irq.c
index 28e3db6f..0d107bce 100644
--- a/apps/nanos-lite/src/irq.c
+++ b/apps/nanos-lite/src/irq.c
@@ -1,14 +1,15 @@
 #include "common.h"
 
 _RegSet* schedule(_RegSet *);
-_RegSet* do_syscall(uintptr_t *);
+_RegSet* do_syscall(_RegSet *);
 
 static _RegSet* do_event(_Event e, _RegSet* r) {
   _RegSet *ret = NULL;
+
   switch (e.event) {
     case _EVENT_IRQ_TIME: ret = schedule(r); break;
     case _EVENT_TRAP: ret = schedule(r); break;
-    case _EVENT_SYSCALL: ret = do_syscall((uintptr_t *)e.cause); break;
+    case _EVENT_SYSCALL: ret = do_syscall(r); break;
     default: panic("Unhandled event ID = %d", e.event);
   }
 
diff --git a/apps/nanos-lite/src/syscall.c b/apps/nanos-lite/src/syscall.c
index 4e41e427..5924d27c 100644
--- a/apps/nanos-lite/src/syscall.c
+++ b/apps/nanos-lite/src/syscall.c
@@ -37,19 +37,27 @@ int sys_brk(uintptr_t brk) {
   return mm_brk(brk);
 }
 
-_RegSet* do_syscall(uintptr_t *args) {
+_RegSet* do_syscall(_RegSet *r) {
   int ret = 0;
-  switch (args[0]) {
-    case SYS_exit: sys_exit(args[1]); break;
-    case SYS_read: ret = sys_read(args[1], (void *)args[2], args[3]); break;
-    case SYS_write: ret = sys_write(args[1], (const void *)args[2], args[3]); break;
-    case SYS_open: ret = sys_open((const char *)args[1], args[2], args[3]); break;
-    case SYS_lseek: ret = sys_lseek(args[1], args[2], args[3]); break;
-    case SYS_close: ret = sys_close(args[1]); break;
-    case SYS_brk: ret = sys_brk(args[1]); break;
-    default: panic("Unhandled syscall ID = %d", args[0]);
+  uintptr_t a[4];
+  a[0] = SYSCALL_ARG1(r);
+  a[1] = SYSCALL_ARG2(r);
+  a[2] = SYSCALL_ARG3(r);
+  a[3] = SYSCALL_ARG4(r);
+  Log("syscall = %d", a[0]);
+
+  switch (a[0]) {
+    case SYS_none: break;
+    case SYS_exit: sys_exit(a[1]); break;
+    case SYS_read: ret = sys_read(a[1], (void *)a[2], a[3]); break;
+    case SYS_write: ret = sys_write(a[1], (const void *)a[2], a[3]); break;
+    case SYS_open: ret = sys_open((const char *)a[1], a[2], a[3]); break;
+    case SYS_lseek: ret = sys_lseek(a[1], a[2], a[3]); break;
+    case SYS_close: ret = sys_close(a[1]); break;
+    case SYS_brk: ret = sys_brk(a[1]); break;
+    default: panic("Unhandled syscall ID = %d", a[0]);
   }
 
-  args[0] = ret;
+  SYSCALL_ARG1(r) = ret;
   return NULL;
 }