nmi_watchdog: Config option to enable new nmi_watchdog

These are the bits that enable the new nmi_watchdog and safely
isolate the old nmi_watchdog.  Only one or the other can run,
not both at the same time.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: gorcunov@gmail.com
Cc: aris@redhat.com
Cc: peterz@infradead.org
LKML-Reference: <1265424425-31562-4-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 13 insertions, 0 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 25c3ed594c54..f80b67e72aa0 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -170,6 +170,19 @@ config DETECT_SOFTLOCKUP
            can be detected via the NMI-watchdog, on platforms that
            support it.)
 
+config NMI_WATCHDOG
+        bool "Detect Hard Lockups with an NMI Watchdog"
+        depends on DEBUG_KERNEL && PERF_EVENTS
+        default y
+        help
+          Say Y here to enable the kernel to use the NMI as a watchdog
+          to detect hard lockups.  This is useful when a cpu hangs for no
+          reason but can still respond to NMIs.  A backtrace is displayed
+          for reviewing and reporting.
+
+          The overhead should be minimal, just an extra NMI every few
+          seconds.
+
 config BOOTPARAM_SOFTLOCKUP_PANIC
         bool "Panic (Reboot) On Soft Lockups"
         depends on DETECT_SOFTLOCKUP