diff --git a/os/common/ports/SIMIA32/chcore.h b/os/common/ports/SIMIA32/chcore.h
index e80419332..14591681a 100644
--- a/os/common/ports/SIMIA32/chcore.h
+++ b/os/common/ports/SIMIA32/chcore.h
@@ -243,6 +243,16 @@ struct port_context {
 #define PORT_WORKING_AREA(s, n)                                             \
   stkalign_t s[THD_WORKING_AREA_SIZE(n) / sizeof (stkalign_t)]
 
+/**
+ * @brief   Priority level verification macro.
+ */
+#define PORT_IRQ_IS_VALID_PRIORITY(n) false
+
+/**
+ * @brief   Priority level verification macro.
+ */
+#define PORT_IRQ_IS_VALID_KERNEL_PRIORITY(n) false
+
 /**
  * @brief   IRQ prologue code.
  * @details This macro must be inserted at the start of all IRQ handlers
@@ -321,7 +331,9 @@ extern "C" {
 /**
  * @brief   Port-related initialization code.
  */
-static inline void port_init(void) {
+static inline void port_init(os_instance_t *oip) {
+
+  (void)oip;
 
   port_irq_sts = (syssts_t)0;
   port_isr_context_flag = false;
diff --git a/os/hal/ports/simulator/posix/hal_lld.c b/os/hal/ports/simulator/posix/hal_lld.c
index 0015f5b24..cf3423484 100755
--- a/os/hal/ports/simulator/posix/hal_lld.c
+++ b/os/hal/ports/simulator/posix/hal_lld.c
@@ -93,10 +93,10 @@ void _sim_check_for_interrupts(void) {
   }
 
   if (int_occurred) {
-    _dbg_check_lock();
+    __dbg_check_lock();
     if (chSchIsPreemptionRequired())
-      chSchDoReschedule();
-    _dbg_check_unlock();
+      chSchDoPreemption();
+    __dbg_check_unlock();
   }
 }
 
diff --git a/os/rt/src/chsys.c b/os/rt/src/chsys.c
index 5c35a4e84..e58d1fdf8 100644
--- a/os/rt/src/chsys.c
+++ b/os/rt/src/chsys.c
@@ -86,16 +86,19 @@ void chSysInit(void) {
 
   /* Initializing default OS instance.*/
   {
-#if (CH_DBG_ENABLE_STACK_CHECK == TRUE) || (CH_CFG_USE_DYNAMIC == TRUE)
+#if CH_DBG_ENABLE_STACK_CHECK == TRUE
     extern stkalign_t __main_thread_stack_base__,
                       __main_thread_stack_end__;
 #endif
 
     static const os_instance_config_t default_cfg = {
       .name             = "c0",
-#if (CH_DBG_ENABLE_STACK_CHECK == TRUE) || (CH_CFG_USE_DYNAMIC == TRUE)
+#if CH_DBG_ENABLE_STACK_CHECK == TRUE
       .mainthread_base  = &__main_thread_stack_base__,
       .mainthread_end   = &__main_thread_stack_end__,
+#elif CH_CFG_USE_DYNAMIC == TRUE
+      .mainthread_base  = NULL,
+      .mainthread_end   = NULL,
 #endif
 #if CH_CFG_NO_IDLE_THREAD == FALSE
       .idlethread_base  = THD_WORKING_AREA_BASE(ch_idle_thread_wa),