Index: kernel/arch/ia64/include/context.h
===================================================================
--- kernel/arch/ia64/include/context.h	(revision d99c1d2ba8c7b2c687d430f2e9fd237046606545)
+++ kernel/arch/ia64/include/context.h	(revision 7b712b60a3329d7528f8fc68effc1878b0911e5c)
@@ -49,11 +49,11 @@
 #define SP_DELTA	(0 + ALIGN_UP(STACK_ITEM_SIZE, STACK_ALIGNMENT))
 
-/* RSE stack starts at the bottom of memory stack. */
+/* RSE stack starts at the bottom of memory stack, hence the division by 2. */
 #define context_set(c, _pc, stack, size)								\
 	do {												\
 		(c)->pc = (uintptr_t) _pc;								\
-		(c)->bsp = ((uintptr_t) stack) + ALIGN_UP((size), REGISTER_STACK_ALIGNMENT);		\
+		(c)->bsp = ((uintptr_t) stack) + ALIGN_UP((size / 2), REGISTER_STACK_ALIGNMENT);	\
 		(c)->ar_pfs &= PFM_MASK; 								\
-		(c)->sp = ((uintptr_t) stack) + ALIGN_UP((size), STACK_ALIGNMENT) - SP_DELTA;		\
+		(c)->sp = ((uintptr_t) stack) + ALIGN_UP((size / 2), STACK_ALIGNMENT) - SP_DELTA;	\
 	} while (0);