[Qemu-devel] [PATCH V9 1/3] docs: vm generation id device's description

[Gal Hammer <ghammer@redhat.com>]

Signed-off-by: Gal Hammer <ghammer@redhat.com>

---
 docs/specs/vmgenid.txt | 27 +++++++++++++++++++++++++++
 1 file changed, 27 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..9a09d11
--- /dev/null
+++ b/docs/specs/vmgenid.txt
@@ -0,0 +1,27 @@
+VIRTUAL MACHINE GENERATION ID
+=============================
+
+The VM generation ID (vmgenid) device is an emulated device which
+expose 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).
+
+Specs is on the web at: http://go.microsoft.com/fwlink/?LinkId=260709
+
+---
+
+The vmgenid device is a sysbus device with the following ACPI ID:
+"QEMU0002".
+
+The device adds a "vmgenid.uuid" property, which can be modifed using
+the -global command line argument or the QMP interface.
+
+The device uses a fixed memory resource: 0xfedf0000-0xfedf0003. The
+guest is expected to write the physical address of the GUID's buffer
+to that memory resource. This allows the device to modify the GUID if
+requested by the management application.
+
+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.
-- 
1.9.3