Index: kernel/Makefile
===================================================================
--- kernel/Makefile	(revision abf6c018de8e29f417e189c669b1514cb9a75462)
+++ kernel/Makefile	(revision 95d45482754feecb799113e94c59c7c41e44b029)
@@ -65,5 +65,5 @@
 ifeq ($(PRECHECK),y)
 	JOBFILE = $(ROOT_PATH)/tools/jobfile.py
-	# XXX: Do not change the order of arguments.
+	# NOTE: You must not change the order of arguments.
 	CC_JOB = $(JOBFILE) $(JOB) $(CC) $< -o $@
 else
Index: kernel/arch/amd64/_link.ld.in
===================================================================
--- kernel/arch/amd64/_link.ld.in	(revision abf6c018de8e29f417e189c669b1514cb9a75462)
+++ kernel/arch/amd64/_link.ld.in	(revision 95d45482754feecb799113e94c59c7c41e44b029)
@@ -33,5 +33,5 @@
 		*(COMMON);      /* global variables */
 
-		/* XXX: bss can't be omitted from the ELF image. */
+		/* bss can't be omitted from the ELF image. */
 		*(.bss);        /* uninitialized static variables */
 
Index: kernel/arch/arm32/include/arch/context_struct.h
===================================================================
--- kernel/arch/arm32/include/arch/context_struct.h	(revision abf6c018de8e29f417e189c669b1514cb9a75462)
+++ kernel/arch/arm32/include/arch/context_struct.h	(revision 95d45482754feecb799113e94c59c7c41e44b029)
@@ -32,5 +32,5 @@
 #include <typedefs.h>
 
-// XXX: This struct must match assembly code in src/context.S
+// NOTE: This struct must match assembly code in src/context.S
 
 /*
Index: kernel/arch/arm32/include/arch/istate_struct.h
===================================================================
--- kernel/arch/arm32/include/arch/istate_struct.h	(revision abf6c018de8e29f417e189c669b1514cb9a75462)
+++ kernel/arch/arm32/include/arch/istate_struct.h	(revision 95d45482754feecb799113e94c59c7c41e44b029)
@@ -32,5 +32,5 @@
 #include <stdint.h>
 
-// XXX: Must match assembly code in src/exc_handler.S
+// NOTE: Must match assembly code in src/exc_handler.S
 
 typedef struct istate {
Index: kernel/arch/ia32/_link.ld.in
===================================================================
--- kernel/arch/ia32/_link.ld.in	(revision abf6c018de8e29f417e189c669b1514cb9a75462)
+++ kernel/arch/ia32/_link.ld.in	(revision 95d45482754feecb799113e94c59c7c41e44b029)
@@ -32,5 +32,5 @@
 		*(COMMON);              /* global variables */
 
-		/* XXX: bss can't be omitted from the ELF image. */
+		/* bss can't be omitted from the ELF image. */
 		*(.bss);                /* uninitialized static variables */
 
Index: kernel/arch/ppc32/src/exception.S
===================================================================
--- kernel/arch/ppc32/src/exception.S	(revision abf6c018de8e29f417e189c669b1514cb9a75462)
+++ kernel/arch/ppc32/src/exception.S	(revision 95d45482754feecb799113e94c59c7c41e44b029)
@@ -126,5 +126,5 @@
 .endm
 
-// XXX: K_UNMAPPED_TEXT_START section starts at 0x100,
+// NOTE: K_UNMAPPED_TEXT_START section starts at 0x100,
 // so all the following .org directives are relative to that.
 #define ABSOLUTE(x) ((x) - 0x100)
Index: kernel/generic/include/lib/refcount.h
===================================================================
--- kernel/generic/include/lib/refcount.h	(revision abf6c018de8e29f417e189c669b1514cb9a75462)
+++ kernel/generic/include/lib/refcount.h	(revision 95d45482754feecb799113e94c59c7c41e44b029)
@@ -64,7 +64,7 @@
 static inline void refcount_up(atomic_refcount_t *rc)
 {
-	// XXX: We can use relaxed operation because acquiring a reference
-	//      implies no ordering relationships. A reference-counted object
-	//      still needs to be synchronized independently of the refcount.
+	// NOTE: We can use relaxed operation because acquiring a reference
+	//       implies no ordering relationships. A reference-counted object
+	//       still needs to be synchronized independently of the refcount.
 
 	int old = atomic_fetch_add_explicit(&rc->__cnt, 1,
@@ -96,6 +96,6 @@
 static inline bool refcount_down(atomic_refcount_t *rc)
 {
-	// XXX: The decrementers don't need to synchronize with each other,
-	//      but they do need to synchronize with the one doing deallocation.
+	// NOTE: The decrementers don't need to synchronize with each other,
+	//       but they do need to synchronize with the one doing deallocation.
 	int old = atomic_fetch_sub_explicit(&rc->__cnt, 1,
 	    memory_order_release);
@@ -104,6 +104,6 @@
 
 	if (old == 0) {
-		// XXX: We are holding the last reference, so we must now
-		//      synchronize with all the other decrementers.
+		// NOTE: We are holding the last reference, so we must now
+		//       synchronize with all the other decrementers.
 
 		int val = atomic_load_explicit(&rc->__cnt,
Index: kernel/generic/src/cpu/cpu.c
===================================================================
--- kernel/generic/src/cpu/cpu.c	(revision abf6c018de8e29f417e189c669b1514cb9a75462)
+++ kernel/generic/src/cpu/cpu.c	(revision 95d45482754feecb799113e94c59c7c41e44b029)
@@ -71,6 +71,6 @@
 		memsetb(cpus, sizeof(cpu_t) * config.cpu_count, 0);
 
-		// XXX: All kernel stacks must be aligned to STACK_SIZE,
-		//      see get_stack_base().
+		// NOTE: All kernel stacks must be aligned to STACK_SIZE,
+		//       see get_stack_base().
 		size_t i;
 		for (i = 0; i < config.cpu_count; i++) {
Index: kernel/generic/src/main/main.c
===================================================================
--- kernel/generic/src/main/main.c	(revision abf6c018de8e29f417e189c669b1514cb9a75462)
+++ kernel/generic/src/main/main.c	(revision 95d45482754feecb799113e94c59c7c41e44b029)
@@ -171,6 +171,6 @@
 	    ALIGN_UP((uintptr_t) kdata_end - config.base, PAGE_SIZE);
 
-	// XXX: All kernel stacks must be aligned to STACK_SIZE,
-	//      see get_stack_base().
+	// NOTE: All kernel stacks must be aligned to STACK_SIZE,
+	//       see get_stack_base().
 
 	/* Place the stack after the kernel, init and ballocs. */
Index: kernel/generic/src/proc/thread.c
===================================================================
--- kernel/generic/src/proc/thread.c	(revision abf6c018de8e29f417e189c669b1514cb9a75462)
+++ kernel/generic/src/proc/thread.c	(revision 95d45482754feecb799113e94c59c7c41e44b029)
@@ -190,6 +190,6 @@
 	kmflags &= ~FRAME_HIGHMEM;
 
-	// XXX: All kernel stacks must be aligned to STACK_SIZE,
-	//      see get_stack_base().
+	// NOTE: All kernel stacks must be aligned to STACK_SIZE,
+	//       see get_stack_base().
 
 	uintptr_t stack_phys =
Index: kernel/generic/src/synch/spinlock.c
===================================================================
--- kernel/generic/src/synch/spinlock.c	(revision abf6c018de8e29f417e189c669b1514cb9a75462)
+++ kernel/generic/src/synch/spinlock.c	(revision 95d45482754feecb799113e94c59c7c41e44b029)
@@ -161,8 +161,8 @@
 bool spinlock_locked(spinlock_t *lock)
 {
-	// XXX: Atomic flag doesn't support simple atomic read (by design),
-	//      so instead we test_and_set and then clear if necessary.
-	//      This function is only used inside assert, so we don't need
-	//      any preemption_disable/enable here.
+	// NOTE: Atomic flag doesn't support simple atomic read (by design),
+	//       so instead we test_and_set and then clear if necessary.
+	//       This function is only used inside assert, so we don't need
+	//       any preemption_disable/enable here.
 
 	bool ret = atomic_flag_test_and_set_explicit(&lock->flag, memory_order_relaxed);