diff -ruN kozos37/extintr.c kozos38/extintr.c
--- kozos37/extintr.c	Mon Jan 26 21:44:44 2009
+++ kozos38/extintr.c	Mon Jan 26 22:57:44 2009
@@ -43,6 +43,8 @@
     struct consreg *cons;
   } regs;
 
+  int (*mask)(struct interrupts *intp);
+  int (*unmask)(struct interrupts *intp);
   int (*checkintr)(struct interrupts *intp);
   int (*intr)(struct interrupts *intp);
   int (*command)(struct interrupts *intp, int id, int size, char *command);
@@ -139,6 +141,68 @@
   return 0;
 }
 
+static struct interrupts *interrupts_search(int id)
+{
+  int i;
+  struct interrupts *intp;
+  for (i = 0; i < EXTINTR_INTERRUPTS_NUM; i++) {
+    intp = &interrupts[i];
+    if (intp->id == id) return intp;
+  }
+  return NULL;
+}
+
+static void preproc(int id)
+{
+  struct interrupts *intp;
+  int i, n;
+
+  /*
+   * 本関数は kz_precall() によりスレッドのディスパッチ前にOS内部から
+   * 呼ばれるので，システムコールを利用してはいけない．
+   */
+
+  if (id == 0)
+    n = 0;
+  else if ((intp = interrupts_search(id)) == NULL)
+    n = EXTINTR_INTERRUPTS_NUM;
+  else
+    n = intp - interrupts;
+
+  for (i = 0; i < EXTINTR_INTERRUPTS_NUM; i++) {
+    intp = &interrupts[i];
+    if (intp->type == INTERRUPTS_TYPE_UNKNOWN)
+      continue;
+    if (i < n)
+      intp->unmask(intp);
+    else
+      intp->mask(intp);
+  }
+
+  return;
+}
+
+static void allmask(int id)
+{
+  preproc(0);
+}
+
+static int timer_mask(struct interrupts *intp)
+{
+  char c;
+  c = EXTINTR_CMD_TIMER_MASK;
+  write(intp->regs.timer->cnt_fd, &c, 1);
+  return 0;
+}
+
+static int timer_unmask(struct interrupts *intp)
+{
+  char c;
+  c = EXTINTR_CMD_TIMER_UNMASK;
+  write(intp->regs.timer->cnt_fd, &c, 1);
+  return 0;
+}
+
 static int timer_checkintr(struct interrupts *intp)
 {
   return extintr_checkfd(intp->regs.timer->read_fd);
@@ -160,6 +224,7 @@
   switch (command[0]) {
   case EXTINTR_CMD_TIMER_USE:
     intp->id = id;
+    kz_precall(id, preproc);
     break;
 
   case EXTINTR_CMD_TIMER_START:
@@ -187,6 +252,8 @@
 static int timer_init(struct interrupts *intp)
 {
   intp->type      = INTERRUPTS_TYPE_TIMER;
+  intp->mask      = timer_mask;
+  intp->unmask    = timer_unmask;
   intp->checkintr = timer_checkintr;
   intp->intr      = timer_intr;
   intp->command   = timer_command;
@@ -194,6 +261,22 @@
   return 0;
 }
 
+static int cons_mask(struct interrupts *intp)
+{
+  char c;
+  c = EXTINTR_CMD_CONSOLE_DISABLE;
+  write(intp->regs.cons->cnt_fd, &c, 1);
+  return 0;
+}
+
+static int cons_unmask(struct interrupts *intp)
+{
+  char c;
+  c = EXTINTR_CMD_CONSOLE_ENABLE;
+  write(intp->regs.cons->cnt_fd, &c, 1);
+  return 0;
+}
+
 static int cons_checkintr(struct interrupts *intp)
 {
   return extintr_checkfd(intp->regs.cons->read_fd);
@@ -219,6 +302,7 @@
   switch (command[0]) {
   case EXTINTR_CMD_CONSOLE_USE: /* コンソールの利用 */
     intp->id = id;
+    kz_precall(id, preproc);
     break;
 
   case EXTINTR_CMD_CONSOLE_ENABLE:
@@ -245,6 +329,8 @@
 static int cons_init(struct interrupts *intp)
 {
   intp->type      = INTERRUPTS_TYPE_CONSOLE;
+  intp->mask      = cons_mask;
+  intp->unmask    = cons_unmask;
   intp->checkintr = cons_checkintr;
   intp->intr      = cons_intr;
   intp->command   = cons_command;
@@ -354,6 +440,9 @@
   extintr_intr_regist(&interrupts[5], & consreg[2],  cons_init);
   extintr_intr_regist(&interrupts[6], &timerreg[3], timer_init);
   extintr_intr_regist(&interrupts[7], & consreg[3],  cons_init);
+
+  kz_precall(0, preproc);
+  kz_precall(kz_getid(), allmask);
 
   extintr_mainloop();
 
diff -ruN kozos37/main.c kozos38/main.c
--- kozos37/main.c	Thu Jan 22 19:52:33 2009
+++ kozos38/main.c	Mon Jan 26 22:57:44 2009
@@ -9,13 +9,13 @@
 #if 0
   stubd_id    = kz_run(stubd_main,    "stubd",     2, 0, NULL);
 #endif
-  outlog_id   = kz_run(outlog_main,   "outlog",    3, 0, NULL);
-  timerd_id   = kz_run(timerd_main,   "timerd",    4, 0, NULL);
+  outlog_id   = kz_run(outlog_main,   "outlog",   20, 0, NULL);
+  timerd_id   = kz_run(timerd_main,   "timerd",   12, 0, NULL);
   idle_id     = kz_run(idle_main,     "idle",     31, 0, NULL);
-  clock_id    = kz_run(clock_main,    "clock",     7, 0, NULL);
-  clock2_id   = kz_run(clock2_main,   "clock2",    7, 0, NULL);
-  clock3_id   = kz_run(clock3_main,   "clock3",    7, 0, NULL);
-  command_id  = kz_run(command_main,  "command",   8, 0, NULL);
+  clock_id    = kz_run(clock_main,    "clock",    10, 0, NULL);
+  clock2_id   = kz_run(clock2_main,   "clock2",   21, 0, NULL);
+  clock3_id   = kz_run(clock3_main,   "clock3",   21, 0, NULL);
+  command_id  = kz_run(command_main,  "command",  11, 0, NULL);
 
   return 0;
 }
diff -ruN kozos37/thread.c kozos38/thread.c
--- kozos37/thread.c	Thu Jan 22 19:52:33 2009
+++ kozos38/thread.c	Mon Jan 26 22:57:44 2009
@@ -27,6 +27,7 @@
 static sigset_t block_old;
 static int block_count = 0;
 static stack_t intrstack;
+static kz_prefunc default_precall = NULL;
 
 kz_thread *current;
 
@@ -290,7 +291,10 @@
 static int thread_precall(int id, kz_prefunc func)
 {
   kz_thread *thp = (kz_thread *)id;
-  thp->precall = func;
+  if (thp)
+    thp->precall = func;
+  else
+    default_precall = func;
   putcurrent();
   return 0;
 }
@@ -469,6 +473,8 @@
 
   if (current->precall) {
     current->precall((int)current);
+  } else if (default_precall) {
+    default_precall((int)current);
   }
 
   /*
diff -ruN kozos37/timerd.c kozos38/timerd.c
--- kozos37/timerd.c	Fri Jan 23 22:04:58 2009
+++ kozos38/timerd.c	Mon Jan 26 22:57:44 2009
@@ -52,7 +52,7 @@
   timebuf **tmpp;
   timebuf *tmp;
   struct timeval tm;
-  int diffmsec;
+  int s, diffmsec;
 
   tmp = kz_kmalloc(sizeof(*tmp));
   tmp->next = NULL;
@@ -60,8 +60,9 @@
 
   gettimeofday(&tm, NULL);
   if (timers) {
-    diffmsec = (tm.tv_sec - alarm_tm.tv_sec) * 1000 + 
-      (tm.tv_usec - alarm_tm.tv_usec) / 1000;
+    s = tm.tv_usec < alarm_tm.tv_usec ? 1 : 0;
+    diffmsec = (-s + tm.tv_sec - alarm_tm.tv_sec) * 1000 + 
+      (s * 1000000 + tm.tv_usec - alarm_tm.tv_usec) / 1000;
     if (timers->msec > diffmsec)
       timers->msec -= diffmsec;
     else