nmi_watchdog: Use a boolean config flag for compiling

Determines if an arch has setup arch specific perf_events and
nmi_watchdog code.  This should restrict compiles to only those
arches ready.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: peterz@infradead.org
Cc: gorcunov@gmail.com
Cc: aris@redhat.com
LKML-Reference: <1266013161-31197-1-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/Kconfig

@@ -52,6 +52,7 @@ config X86
 	select HAVE_KERNEL_LZO
 	select HAVE_HW_BREAKPOINT
 	select PERF_EVENTS
+	select PERF_EVENTS_NMI
 	select ANON_INODES
 	select HAVE_ARCH_KMEMCHECK
 	select HAVE_USER_RETURN_NOTIFIER

init/Kconfig

@@ -946,6 +946,11 @@ config PERF_USE_VMALLOC
 	help
 	  See tools/perf/design.txt for details
 
+config PERF_EVENTS_NMI
+	bool
+	help
+	  Arch has support for nmi_watchdog
+
 menu "Kernel Performance Events And Counters"
 
 config PERF_EVENTS

lib/Kconfig.debug

@@ -172,8 +172,7 @@ config DETECT_SOFTLOCKUP
 
 config NMI_WATCHDOG
 	bool "Detect Hard Lockups with an NMI Watchdog"
-	depends on DEBUG_KERNEL && PERF_EVENTS
-	depends on X86
+	depends on DEBUG_KERNEL && PERF_EVENTS && PERF_EVENTS_NMI
 	default y
 	help
 	  Say Y here to enable the kernel to use the NMI as a watchdog