Merge branch 'perf/core' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux...

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

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 03bc471..f815283 100644 (file)
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -26,6 +26,36 @@ config XEN_SELFBALLOONING
          kernel boot parameter.  Note that systems without a sufficiently
          large swap device should not enable self-ballooning.
 
+config XEN_BALLOON_MEMORY_HOTPLUG
+       bool "Memory hotplug support for Xen balloon driver"
+       default n
+       depends on XEN_BALLOON && MEMORY_HOTPLUG
+       help
+         Memory hotplug support for Xen balloon driver allows expanding memory
+         available for the system above limit declared at system startup.
+         It is very useful on critical systems which require long
+         run without rebooting.
+
+         Memory could be hotplugged in following steps:
+
+           1) dom0: xl mem-max <domU> <maxmem>
+              where <maxmem> is >= requested memory size,
+
+           2) dom0: xl mem-set <domU> <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,
+
+           3) domU: for i in /sys/devices/system/memory/memory*/state; do \
+                      [ "`cat "$i"`" = offline ] && echo online > "$i"; done
+
+         Memory could be onlined automatically on domU by adding following line to udev rules:
+
+         SUBSYSTEM=="memory", ACTION=="add", RUN+="/bin/sh -c '[ -f /sys$devpath/state ] && echo online > /sys$devpath/state'"
+
+         In that case step 3 should be omitted.
+
 config XEN_SCRUB_PAGES
        bool "Scrub pages before returning them to system"
        depends on XEN_BALLOON