[IA64] introduce compile time option to disable optvfault.

Debugging optvfault path is extremely difficult because
it was run with psr.ic = 0.
Make it easy to differentiate the bug in optvfault path from
other normal execution path with psr.ic = 0 by introducing compile
time option to disable optvfault.

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>

diff -r 61ba5322e8b3 xen/arch/ia64/Rules.mk
--- a/xen/arch/ia64/Rules.mk	Thu Aug 14 14:17:13 2008 +0900
+++ b/xen/arch/ia64/Rules.mk	Thu Aug 14 14:18:09 2008 +0900
@@ -14,6 +14,7 @@
 xen_ia64_tlb_track	?= y
 xen_ia64_tlb_track_cnt	?= n
 xen_ia64_tlbflush_clock	?= y
+xen_ia64_disable_optvfault ?= n
 
 # Used only by linux/Makefile.
 AFLAGS_KERNEL  += -mconstant-gp -nostdinc $(CPPFLAGS)
@@ -67,6 +68,9 @@
 else
 CFLAGS += -DVHPT_ENABLED=0
 endif
+ifeq ($(xen_ia64_disable_optvfault),y)
+CFLAGS += -DCONFIG_XEN_IA64_DISABLE_OPTVFAULT
+endif
 
 LDFLAGS := -g
 
diff -r 61ba5322e8b3 xen/arch/ia64/vmx/vmx_ivt.S
--- a/xen/arch/ia64/vmx/vmx_ivt.S	Thu Aug 14 14:17:13 2008 +0900
+++ b/xen/arch/ia64/vmx/vmx_ivt.S	Thu Aug 14 14:18:09 2008 +0900
@@ -973,6 +973,7 @@
 ENTRY(vmx_virtualization_fault)
 //    VMX_DBG_FAULT(37)
     mov r31=pr
+#ifndef CONFIG_XEN_IA64_DISABLE_OPTVFAULT
     movl r30 = virtualization_fault_table
     mov r23=b0
     ;;
@@ -981,6 +982,7 @@
     mov b0=r30
     br.sptk.many b0
     ;;
+#endif
 vmx_virtualization_fault_back:
     mov r19=37
     adds r16 = IA64_VCPU_CAUSE_OFFSET,r21