xen_balloon: support memory auto onlining policy

[cascardo/linux.git] / drivers / xen / Kconfig

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 73708ac..979a831 100644 (file)
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -37,23 +37,30 @@ config XEN_BALLOON_MEMORY_HOTPLUG
 
          Memory could be hotplugged in following steps:
 
-           1) dom0: xl mem-max <domU> <maxmem>
+           1) target domain: ensure that memory auto online policy is in
+              effect by checking /sys/devices/system/memory/auto_online_blocks
+              file (should be 'online').
+
+           2) control domain: xl mem-max <target-domain> <maxmem>
               where <maxmem> is >= requested memory size,
 
-           2) dom0: xl mem-set <domU> <memory>
+           3) control domain: xl mem-set <target-domain> <memory>
               where <memory> is requested memory size; alternatively memory
               could be added by writing proper value to
               /sys/devices/system/xen_memory/xen_memory0/target or
-              /sys/devices/system/xen_memory/xen_memory0/target_kb on dumU,
+              /sys/devices/system/xen_memory/xen_memory0/target_kb on the
+              target domain.
 
-           3) domU: for i in /sys/devices/system/memory/memory*/state; do \
-                      [ "`cat "$i"`" = offline ] && echo online > "$i"; done
+         Alternatively, if memory auto onlining was not requested at step 1
+         the newly added memory can be manually onlined in the target domain
+         by doing the following:
 
-         Memory could be onlined automatically on domU by adding following line to udev rules:
+               for i in /sys/devices/system/memory/memory*/state; do \
+                 [ "`cat "$i"`" = offline ] && echo online > "$i"; done
 
-         SUBSYSTEM=="memory", ACTION=="add", RUN+="/bin/sh -c '[ -f /sys$devpath/state ] && echo online > /sys$devpath/state'"
+         or by adding the following line to udev rules:
 
-         In that case step 3 should be omitted.
+         SUBSYSTEM=="memory", ACTION=="add", RUN+="/bin/sh -c '[ -f /sys$devpath/state ] && echo online > /sys$devpath/state'"
 
 config XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
        int "Hotplugged memory limit (in GiB) for a PV guest"