diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 2ad6301..3d22bb8 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -399,6 +399,10 @@
 	def_bool y
 	depends on ((MWINCHIP3D || MWINCHIP2 || MCRUSOE || MEFFICEON || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || MK8 || MVIAC3_2 || MVIAC7 || MGEODEGX1 || MGEODE_LX || MCORE2) && !X86_NUMAQ) || X86_64
 
+config X86_CMPXCHG64
+	def_bool y
+	depends on X86_PAE || X86_64
+
 # this should be set for all -march=.. options where the compiler
 # generates cmov.
 config X86_CMOV