From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50763) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yn6Lm-0003cb-Bw for qemu-devel@nongnu.org; Tue, 28 Apr 2015 10:19:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Yn6Lj-0000za-26 for qemu-devel@nongnu.org; Tue, 28 Apr 2015 10:19:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60361) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yn6Li-0000zF-Rr for qemu-devel@nongnu.org; Tue, 28 Apr 2015 10:18:59 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t3SEIveh028974 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Tue, 28 Apr 2015 10:18:57 -0400 Message-ID: <553F971F.9050204@redhat.com> Date: Tue, 28 Apr 2015 17:20:15 +0300 From: Gal Hammer MIME-Version: 1.0 References: <1430133591-6197-1-git-send-email-ghammer@redhat.com> <1430133591-6197-2-git-send-email-ghammer@redhat.com> <20150427155221-mutt-send-email-mst@redhat.com> In-Reply-To: <20150427155221-mutt-send-email-mst@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH V15 1/5] docs: vm generation id device's description List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: imammedo@redhat.com, qemu-devel@nongnu.org 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 >> --- >> 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