Index: arch/ia64/include/mm/frame.h
===================================================================
--- arch/ia64/include/mm/frame.h	(revision 9e5938dc1a676244e7a61330a207a7bc3ec67806)
+++ arch/ia64/include/mm/frame.h	(revision bc314be837c993a70ed30ed4372ac9aa7b16138b)
@@ -30,5 +30,12 @@
 #define __ia64_FRAME_H__
 
-#define FRAME_WIDTH   14	/* 16K */
+/*
+ * Frame is defined to be 64K long.
+ * Such a relatively big frame size is used because of kernel stack requirements
+ * and organization. Portion of the stack reserved for RSE must be at least 16K
+ * long. If the memory stack is to have some space allocated, the next available
+ * frame size (i.e. 64K) needs to be used.
+ */
+#define FRAME_WIDTH   16	/* 64K */
 #define FRAME_SIZE		(1<<FRAME_WIDTH)
 
Index: arch/ia64/include/register.h
===================================================================
--- arch/ia64/include/register.h	(revision 9e5938dc1a676244e7a61330a207a7bc3ec67806)
+++ arch/ia64/include/register.h	(revision bc314be837c993a70ed30ed4372ac9aa7b16138b)
@@ -42,6 +42,4 @@
 #define PSR_RT_MASK	(1<<27)
 #define PSR_IT_MASK	0x0000001000000000
-
-
 
 /** Application registers. */
Index: arch/ia64/src/ivt.S
===================================================================
--- arch/ia64/src/ivt.S	(revision 9e5938dc1a676244e7a61330a207a7bc3ec67806)
+++ arch/ia64/src/ivt.S	(revision bc314be837c993a70ed30ed4372ac9aa7b16138b)
@@ -38,4 +38,10 @@
 #endif
 
+/** Partitioning of bank 0 registers. */
+#define R_OFFS 		r16
+#define R_HANDLER	r17
+#define R_RET		r18
+#define R_KSTACK	r23	/* keep in sync with before_thread_runs_arch() */
+
 /** Heavyweight interrupt handler
  *
@@ -55,8 +61,6 @@
 .macro HEAVYWEIGHT_HANDLER offs, handler=universal_handler
     .org ivt + \offs
-	mov r24 = \offs
-	movl r25 = \handler ;;
-	mov ar.k0 = r24
-	mov ar.k1 = r25
+	mov R_OFFS = \offs
+	movl R_HANDLER = \handler ;;
 	br heavyweight_handler
 .endm
@@ -65,4 +69,8 @@
 heavyweight_handler:
     /* 1. copy interrupt registers into bank 0 */
+    
+	/*
+	 * Note that r24-r31 from bank0 can be used only as long as PSR.ic = 0.
+	 */
 	mov r24 = cr.iip
 	mov r25 = cr.ipsr
@@ -118,9 +126,7 @@
 	
     /* steps 6 - 15 are done by heavyweight_handler_inner() */
-	mov r24 = b0 		/* save b0 belonging to interrupted context */
-	mov r26 = ar.k0
-	mov r25 = ar.k1
-	br.call.sptk.many rp = heavyweight_handler_inner
-0:	mov b0 = r24		/* restore b0 belonging to the interrupted context */
+	mov R_RET = b0 		/* save b0 belonging to interrupted context */
+	br.call.sptk.many b0 = heavyweight_handler_inner
+0:	mov b0 = R_RET		/* restore b0 belonging to the interrupted context */
 
     /* 16. RSE switch to interrupted context */
@@ -185,7 +191,7 @@
 	
 	/* bank 0 is going to be shadowed, copy essential data from there */
-	mov loc1 = r24	/* b0 belonging to interrupted context */
-	mov loc2 = r25
-	mov out0 = r26
+	mov loc1 = R_RET	/* b0 belonging to interrupted context */
+	mov loc2 = R_HANDLER
+	mov out0 = R_OFFS
 	
 	add out1 = STACK_SCRATCH_AREA_SIZE, r12
@@ -324,5 +330,5 @@
 	srlz.d
 
-	mov r24 = loc1
+	mov R_RET = loc1
 	mov ar.pfs = loc0
 	br.ret.sptk.many b0
Index: arch/ia64/src/proc/scheduler.c
===================================================================
--- arch/ia64/src/proc/scheduler.c	(revision 9e5938dc1a676244e7a61330a207a7bc3ec67806)
+++ arch/ia64/src/proc/scheduler.c	(revision bc314be837c993a70ed30ed4372ac9aa7b16138b)
@@ -30,9 +30,10 @@
 #include <proc/thread.h>
 #include <arch.h>
+#include <arch/register.h>
 #include <arch/mm/tlb.h>
 #include <config.h>
 #include <align.h>
 
-/** Record kernel stack address in ar.k7 and make sure it is mapped in DTR. */
+/** Record kernel stack address in bank 0 r23 and make sure it is mapped in DTR. */
 void before_thread_runs_arch(void)
 {
@@ -50,9 +51,12 @@
 	
 	/*
-	 * Record address of kernel stack to ar.k7
-	 * where it will be found after switch
-	 * from userspace.
+	 * Record address of kernel stack to bank 0 r23
+	 * where it will be found after switch from userspace.
 	 */
-	__asm__ volatile ("mov ar.k7 = %0\n" : : "r" (THREAD->kstack));
+	__asm__ volatile (
+		"bsw.0\n"
+		"mov r23 = %0\n"
+		"bsw.1\n"
+		 : : "r" (THREAD->kstack));
 }