On 27/04/2015 16:55, Michael S. Tsirkin wrote:
On Mon, Apr 27, 2015 at 02:19:47PM +0300, Gal Hammer wrote:
Signed-off-by: Gal Hammer <gham...@redhat.com>
---
docs/specs/vmgenid.txt | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
create mode 100644 docs/specs/vmgenid.txt
diff --git a/docs/specs/vmgenid.txt b/docs/specs/vmgenid.txt
new file mode 100644
index 0000000..86ce6ab
--- /dev/null
+++ b/docs/specs/vmgenid.txt
@@ -0,0 +1,35 @@
+VIRTUAL MACHINE GENERATION ID
+=============================
+
+Copyright (C) 2014 Red Hat, Inc.
It's 2015, isn't it?
+
+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.
The value is up to user, let's not claim it's cryptographically random.
I'll add a sentence that clear this issue.
+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 sysbus device with the following ACPI ID:
+"QEMU0002".
No one is expected to locate it using that ID, right?
Nope. According to the specs the device should be identified through its
_CID and/or _DDN names.
+
+The device adds a "vmgenid.uuid" property, which can be modified using
+the -global command line argument or the QMP interface.
+
+The device uses a fixed memory resource: 0xfedf0000-0xfedf000f to store
+the GUID's buffer.
+
+According to the specification, any change to the GUID executes an
+ACPI notification. The vmgenid device triggers the GPE._E00 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.
--
2.1.0