Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging

[mirror_qemu.git] / docs / memory-hotplug.txt

diff --git a/docs/memory-hotplug.txt b/docs/memory-hotplug.txt
index f70571df0ca7fb19af62dd61d34206e307fc98ed..6aa5e17e26090f619787de7b71888093fb9d0117 100644 (file)
--- a/docs/memory-hotplug.txt
+++ b/docs/memory-hotplug.txt
@@ -4,9 +4,7 @@ QEMU memory hotplug
 This document explains how to use the memory hotplug feature in QEMU,
 which is present since v2.1.0.
 
-Please, note that memory hotunplug is not supported yet. This means
-that you're able to add memory, but you're not able to remove it.
-Also, proper guest support is required for memory hotplug to work.
+Guest support is required for memory hotplug to work.
 
 Basic RAM hotplug
 -----------------
@@ -26,7 +24,7 @@ Where,
 
 For example, the following command-line:
 
- qemu [...] 1G,slots=3,maxmem=4G
+ qemu [...] -m 1G,slots=3,maxmem=4G
 
 Creates a guest with 1GB of memory and three hotpluggable memory slots.
 The hotpluggable memory slots are empty when the guest is booted, so all
@@ -64,7 +62,7 @@ It's also possible to start a guest with memory cold-plugged into the
 hotpluggable memory slots. This might seem counterintuitive at first,
 but this allows for a lot of flexibility when using the file backend.
 
-In the following command-line example, a 8GB guest is created where 6GB
+In the following command-line example, an 8GB guest is created where 6GB
 comes from regular RAM, 1GB is a 1GB hugepage page and 256MB is from
 2MB pages. Also, the guest has additional memory slots to hotplug more
 2GB if needed:
@@ -74,3 +72,22 @@ comes from regular RAM, 1GB is a 1GB hugepage page and 256MB is from
    -device pc-dimm,id=dimm1,memdev=mem1 \
    -object memory-backend-file,id=mem2,size=256M,mem-path=/mnt/hugepages-2MB \
    -device pc-dimm,id=dimm2,memdev=mem2
+
+
+RAM hot-unplug
+---------------
+
+In order to be able to hot unplug pc-dimm device, QEMU has to be told the ids
+of pc-dimm device and memory backend object. The ids were assigned when you hot
+plugged memory.
+
+Two monitor commands are used to hot unplug memory:
+
+ - "device_del": deletes a front-end pc-dimm device
+ - "object_del": deletes a memory backend object
+
+For example, assuming that the pc-dimm device with id "dimm1" exists, and its memory
+backend is "mem1", the following commands tries to remove it.
+
+  (qemu) device_del dimm1
+  (qemu) object_del mem1