[v19,2/9] docs: vm generation id device's description

Commit Message

Igor Mammedov Jan. 28, 2016, 10:54 a.m. UTC

From: Gal Hammer <[e-mail]>

Signed-off-by: Gal Hammer <[e-mail]>
Signed-off-by: Igor Mammedov <[e-mail]>
Reviewed-by: Eric Blake <[e-mail]>
---
 docs/specs/vmgenid.txt | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 docs/specs/vmgenid.txt

Patch

diff --git a/docs/specs/vmgenid.txt b/docs/specs/vmgenid.txt
new file mode 100644
index 0000000..462d17f
--- /dev/null
+++ b/docs/specs/vmgenid.txt
@@ -0,0 +1,36 @@ 
+VIRTUAL MACHINE GENERATION ID
+=============================
+
+Copyright (C) 2016 Red Hat, Inc.
+
+This work is licensed under the terms of the GNU GPL, version 2 or later.
+See the COPYING file in the top-level directory.
+
+===
+
+The VM generation ID (vmgenid) device is an emulated device which
+exposes a 128-bit, cryptographically random, integer value identifier.
+This allows management applications (e.g. libvirt) to notify the guest
+operating system when the virtual machine is executed with a different
+configuration (e.g. snapshot execution or creation from a template).
+
+This is specified on the web at: http://go.microsoft.com/fwlink/?LinkId=260709
+
+---
+
+The vmgenid device is a PCI device with the following ACPI ID: "QEMU0003".
+
+The device has a "vmgenid.guid" property, which can be set using
+the command line argument or the QMP interface.
+For example:
+QEMU  -device vmgenid,id=FOO,guid="324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb87"
+
+Or to change guid in runtime use:
+ qom-set "/machine/peripheral/FOO.guid" "124e6eaf-d1d1-4bf6-bf41-b9bb6c91fb87"
+
+According to the specification, any change to the GUID executes an
+ACPI notification. The vmgenid device triggers the \_GPE._E00 handler
+which executes the ACPI Notify operation.
+
+Although not specified in Microsoft's document, it is assumed that the
+device is expected to use the little-endian system.