diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
index 66ef8f35613..9f401350f50 100644
--- a/Documentation/cpu-hotplug.txt
+++ b/Documentation/cpu-hotplug.txt
@@ -207,6 +207,30 @@ by making it not-removable.
 
 In such cases you will also notice that the online file is missing under cpu0.
 
+Q: Is CPU0 removable on X86?
+A: Yes. If kernel is compiled with CONFIG_BOOTPARAM_HOTPLUG_CPU0=y, CPU0 is
+removable by default. Otherwise, CPU0 is also removable by kernel option
+cpu0_hotplug.
+
+But some features depend on CPU0. Two known dependencies are:
+
+1. Resume from hibernate/suspend depends on CPU0. Hibernate/suspend will fail if
+CPU0 is offline and you need to online CPU0 before hibernate/suspend can
+continue.
+2. PIC interrupts also depend on CPU0. CPU0 can't be removed if a PIC interrupt
+is detected.
+
+It's said poweroff/reboot may depend on CPU0 on some machines although I haven't
+seen any poweroff/reboot failure so far after CPU0 is offline on a few tested
+machines.
+
+Please let me know if you know or see any other dependencies of CPU0.
+
+If the dependencies are under your control, you can turn on CPU0 hotplug feature
+either by CONFIG_BOOTPARAM_HOTPLUG_CPU0 or by kernel parameter cpu0_hotplug.
+
+--Fenghua Yu <fenghua.yu@intel.com>
+
 Q: How do i find out if a particular CPU is not removable?
 A: Depending on the implementation, some architectures may show this by the
 absence of the "online" file. This is done if it can be determined ahead of
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9776f068306..f7cbe1d98cb 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1984,6 +1984,20 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 
 	nox2apic	[X86-64,APIC] Do not enable x2APIC mode.
 
+	cpu0_hotplug	[X86] Turn on CPU0 hotplug feature when
+			CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
+			Some features depend on CPU0. Known dependencies are:
+			1. Resume from suspend/hibernate depends on CPU0.
+			Suspend/hibernate will fail if CPU0 is offline and you
+			need to online CPU0 before suspend/hibernate.
+			2. PIC interrupts also depend on CPU0. CPU0 can't be
+			removed if a PIC interrupt is detected.
+			It's said poweroff/reboot may depend on CPU0 on some
+			machines although I haven't seen such issues so far
+			after CPU0 is offline on a few tested machines.
+			If the dependencies are under your control, you can
+			turn on cpu0_hotplug.
+
 	nptcg=		[IA-64] Override max number of concurrent global TLB
 			purges which is reported from either PAL_VM_SUMMARY or
 			SAL PALO.