diff --git a/framework/rsc_enum.h b/framework/rsc_enum.h
index db312c9..9013406 100644
--- a/framework/rsc_enum.h
+++ b/framework/rsc_enum.h
@@ -66,10 +66,34 @@ enum hw_resource {
 
 typedef uint8_t ResourceMap[RSCMAP_LEN];
 
-#define RSC_IS_FREE(rscmap, rsc) (0 == (rscmap[((rsc)>>3)&0xFF] & (1<<((rsc)&0x7))))
-#define RSC_IS_HELD(rscmap, rsc) (!RSC_IS_FREE(rscmap, rsc))
-#define RSC_CLAIM(rscmap, rsc)   do { rscmap[((rsc)>>3)&0xFF] |= (1<<((rsc)&0x7)); } while(0)
-#define RSC_FREE(rscmap, rsc)   do { rscmap[((rsc)>>3)&0xFF] &= ~(1<<((rsc)&0x7)); } while(0)
+static inline bool rscmap_is_free(ResourceMap *rscmap, Resource rsc)
+{
+    return (0 == (*rscmap[((rsc)>>3)&0xFF] & (1<<((rsc)&0x7))));
+}
 
+static inline bool rscmap_is_held(ResourceMap *rscmap, Resource rsc)
+{
+    return !rscmap_is_free(rscmap, rsc);
+}
+
+static inline void rscmap_claim(ResourceMap *rscmap, Resource rsc)
+{
+    *rscmap[((rsc)>>3)&0xFF] |= (1<<((rsc)&0x7));
+}
+
+static inline void rscmap_free(ResourceMap *rscmap, Resource rsc)
+{
+    *rscmap[((rsc)>>3)&0xFF] &= ~(1<<((rsc)&0x7));
+}
+
+//#define RSC_IS_FREE(rscmap, rsc) (0 == (rscmap[((rsc)>>3)&0xFF] & (1<<((rsc)&0x7))))
+//#define RSC_IS_HELD(rscmap, rsc) (!RSC_IS_FREE(rscmap, rsc))
+//#define RSC_CLAIM(rscmap, rsc)   do { rscmap[((rsc)>>3)&0xFF] |= (1<<((rsc)&0x7)); } while(0)
+//#define RSC_FREE(rscmap, rsc)   do { rscmap[((rsc)>>3)&0xFF] &= ~(1<<((rsc)&0x7)); } while(0)
+
+#define RSC_IS_FREE(rscmap, rsc) rscmap_is_free(&rscmap, (rsc))
+#define RSC_IS_HELD(rscmap, rsc) rscmap_is_held(&rscmap, (rsc))
+#define RSC_CLAIM(rscmap, rsc)   rscmap_claim(&rscmap, (rsc))
+#define RSC_FREE(rscmap, rsc)    rscmap_free(&rscmap, (rsc))
 
 #endif //GEX_F072_RSC_ENUM_H
diff --git a/gex.mk b/gex.mk
index 0b7e2fe..84ff98e 100644
--- a/gex.mk
+++ b/gex.mk
@@ -88,7 +88,7 @@ GEX_CDEFS = $(GEX_CDEFS_BASE) \
     -DDEBUG_VFS=0 \
     -DDEBUG_FLASH_WRITE=0 \
     -DVERBOSE_HARDFAULT=1 \
-    -DUSE_STACK_MONITOR=0 \
+    -DUSE_STACK_MONITOR=1 \
     -DUSE_DEBUG_UART=1 \
     -DDEBUG_MALLOC=0 \
     -DDEBUG_RSC=0
diff --git a/platform/irq_dispatcher.c b/platform/irq_dispatcher.c
index 40715a1..7f00d8e 100644
--- a/platform/irq_dispatcher.c
+++ b/platform/irq_dispatcher.c
@@ -2,12 +2,50 @@
 // Created by MightyPork on 2018/01/14.
 //
 
-#include <stm32f072xb.h>
+#include <utils/hexdump.h>
 #include "platform.h"
 #include "irq_dispatcher.h"
 
+struct cbslot {
+    IrqCallback callback;
+    void *arg;
+};
+
+static struct callbacks_ {
+    struct cbslot usart1;
+    struct cbslot usart2;
+    struct cbslot usart3;
+#ifdef USART4
+    struct cbslot usart4;
+#endif
+#ifdef USART5
+    struct cbslot usart5;
+#endif
+    struct cbslot dma1_1;
+    struct cbslot dma1_2;
+    struct cbslot dma1_3;
+    struct cbslot dma1_4;
+    struct cbslot dma1_5;
+    struct cbslot dma1_6;
+    struct cbslot dma1_7;
+    struct cbslot dma1_8;
+
+    struct cbslot dma2_1;
+    struct cbslot dma2_2;
+    struct cbslot dma2_3;
+    struct cbslot dma2_4;
+    struct cbslot dma2_5;
+    struct cbslot dma2_6;
+    struct cbslot dma2_7;
+    struct cbslot dma2_8;
+
+    // XXX add more callbacks here when needed
+} callbacks;
+
 void irqd_init(void)
 {
+    memset(&callbacks, 0, sizeof(callbacks));
+
 //    NVIC_EnableIRQ(WWDG_IRQn);                  /*!< Window WatchDog Interrupt                                       */
 //    NVIC_EnableIRQ(PVD_VDDIO2_IRQn);            /*!< PVD & VDDIO2 Interrupt through EXTI Lines 16 and 31             */
 //    NVIC_EnableIRQ(RTC_IRQn);                   /*!< RTC Interrupt through EXTI Lines 17, 19 and 20                  */
@@ -47,6 +85,8 @@ void irqd_init(void)
 //    NVIC_EnableIRQ(TIM1_BRK_UP_TRG_COM_IRQn);   /*!< TIM1 Break, Update, Trigger and Commutation Interrupt           */ // - handled by hal msp init
 //    NVIC_EnableIRQ(TIM1_CC_IRQn);               /*!< TIM1 Capture Compare Interrupt                                  */
 //    NVIC_EnableIRQ(USB_IRQn);                   /*!< USB global Interrupt  & EXTI Line18 Interrupt                   */ // - USB IRQ is handled by the USB library
+
+    hexDump("Callbacks", &callbacks, sizeof(callbacks));
 }
 
 //void Default_Handler(void)
@@ -54,41 +94,6 @@ void irqd_init(void)
 //    warn("Missing IRQHandler, ISPR[0]=0x%p", (void*)NVIC->ISPR[0]);
 //}
 
-struct cbslot {
-    IrqCallback callback;
-    void *arg;
-};
-
-static struct callbacks_ {
-    struct cbslot usart1;
-    struct cbslot usart2;
-    struct cbslot usart3;
-#ifdef USART4
-    struct cbslot usart4;
-#endif
-#ifdef USART5
-    struct cbslot usart5;
-#endif
-    struct cbslot dma1_1;
-    struct cbslot dma1_2;
-    struct cbslot dma1_3;
-    struct cbslot dma1_4;
-    struct cbslot dma1_5;
-    struct cbslot dma1_6;
-    struct cbslot dma1_7;
-    struct cbslot dma1_8;
-
-    struct cbslot dma2_1;
-    struct cbslot dma2_2;
-    struct cbslot dma2_3;
-    struct cbslot dma2_4;
-    struct cbslot dma2_5;
-    struct cbslot dma2_6;
-    struct cbslot dma2_7;
-    struct cbslot dma2_8;
-
-    // XXX add more callbacks here when needed
-} callbacks = {0};
 
 static struct cbslot *get_slot_for_periph(void *periph)
 {
@@ -142,7 +147,12 @@ static struct cbslot *get_slot_for_periph(void *periph)
 
 void irqd_attach(void *periph, IrqCallback callback, void *arg)
 {
+    dbg("Attach irqd for periph %p, cb %p()", periph, callback);
+
+    hexDump("Callbacks", &callbacks, sizeof(callbacks));
+
     struct cbslot *slot = get_slot_for_periph(periph);
+    dbg("slot %p cb is %p()", slot, slot->callback);
     assert_param(slot->callback == NULL);
     slot->callback = callback;
     slot->arg = arg;
diff --git a/platform/plat_init.c b/platform/plat_init.c
index 743babd..12bf0cb 100644
--- a/platform/plat_init.c
+++ b/platform/plat_init.c
@@ -26,10 +26,11 @@ void plat_init(void)
     Indicator_Init();
     DebugUart_Init(); // <- only the resource claim
 
+    irqd_init();
+
     dbg("Loading settings ...");
     // Load settings from Flash and apply (includes System settings and all Unit settings)
     settings_load(); // XXX maybe this should be moved to the main task
 
     comm_init();
-    irqd_init();
 }