lockup_detector: Introduce CONFIG_HARDLOCKUP_DETECTOR

This new config is deemed to simplify even more the lockup detector
dependencies and can make it easier to bring a smooth sorting
between archs that support the new generic lockup detector and those
that still have their own, especially for those that are in the
middle of this migration.

Instead of checking whether we have CONFIG_LOCKUP_DETECTOR +
CONFIG_PERF_EVENTS_NMI each time an arch wants to know if it needs
to build its own lockup detector, take a shortcut with this new
config. It is enabled only if the hardlockup detection part of
the whole lockup detector is on.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index 89b0efb50948..35084f280087 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -147,5 +147,9 @@ config HAVE_USER_RETURN_NOTIFIER
 
 config HAVE_PERF_EVENTS_NMI
         bool
+        help
+          System hardware can generate an NMI using the perf event
+          subsystem.  Also has support for calculating CPU cycle events
+          to determine how many clock cycles in a given period.
 
 source "kernel/gcov/Kconfig"