i386, x86-64: show that CONFIG_HOTPLUG_CPU is required for suspend on SMP

It's not sufficiently documented that CONFIG_HOTPLUG_CPU is required for
suspend/hibernation on SMP.

Point out the non-obvious.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index 145bb824b2a8..5ce94430c019 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -428,12 +428,15 @@ config NR_CPUS
           memory in the static kernel configuration.
 
 config HOTPLUG_CPU
-        bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
+        bool "Support for suspend on SMP and hot-pluggable CPUs (EXPERIMENTAL)"
         depends on SMP && HOTPLUG && EXPERIMENTAL
         help
                 Say Y here to experiment with turning CPUs off and on.  CPUs
                 can be controlled through /sys/devices/system/cpu/cpu#.
-                Say N if you want to disable CPU hotplug.
+                This is also required for suspend/hibernation on SMP systems.
+
+                Say N if you want to disable CPU hotplug and don't need to
+                suspend.
 
 config ARCH_ENABLE_MEMORY_HOTPLUG
         def_bool y