1 files changed, 14 insertions, 0 deletions

diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index 44ee7f6acf7b..82cb2a3f127a 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -303,6 +303,20 @@ config HPET_TIMER
           as it is off-chip.  You can find the HPET spec at
           <http://www.intel.com/labs/platcomp/hpet/hpetspec.htm>.
 
+config X86_PM_TIMER
+        bool "PM timer"
+        default y
+        help
+          Support the ACPI PM timer for time keeping. This is slow,
+          but is useful on some chipsets without HPET on systems with more
+          than one CPU. On a single processor or single socket multi core
+          system it is normally not required.
+          When the PM timer is active 64bit vsyscalls are disabled
+          and should not be enabled (/proc/sys/kernel/vsyscall64 should
+          not be changed).
+          The kernel selects the PM timer only as a last resort, so it is
+          useful to enable just in case.
+
 config HPET_EMULATE_RTC
         bool "Provide RTC interrupt"
         depends on HPET_TIMER && RTC=y