From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53363) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XOnjE-0000gT-Hw for qemu-devel@nongnu.org; Tue, 02 Sep 2014 09:02:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XOnj8-0002HR-D1 for qemu-devel@nongnu.org; Tue, 02 Sep 2014 09:02:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59604) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XOnj8-0002HK-4C for qemu-devel@nongnu.org; Tue, 02 Sep 2014 09:02:26 -0400 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s82D2Ott027632 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Tue, 2 Sep 2014 09:02:25 -0400 Message-ID: <5405BFEC.8070403@redhat.com> Date: Tue, 02 Sep 2014 16:02:36 +0300 From: Gal Hammer MIME-Version: 1.0 References: <1407670353-14971-1-git-send-email-ghammer@redhat.com> <1407670353-14971-3-git-send-email-ghammer@redhat.com> <53E7AA72.6030204@redhat.com> <53E9CA22.8090300@redhat.com> <53F07AB2.4070601@redhat.com> <54041E26.8070406@redhat.com> <540434EA.8080203@redhat.com> In-Reply-To: <540434EA.8080203@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 2/2] i386: Add a Virtual Machine Generation ID device. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , qemu-devel@nongnu.org On 01/09/2014 11:57, Paolo Bonzini wrote: > Il 01/09/2014 09:20, Gal Hammer ha scritto: >>> >>> We are still in the process of defining which devices/methods go in the >>> DSDT and which go in the SSDT. We had bad experiences with ACPI table >>> migration in 2.1, and one plan to fix them is the following: >>> >>> * the DSDT should always be the same size no matter what command line >>> options are there >>> >>> * the SSDT should have the exact same content (byte-for-byte) for >>> different versions of QEMU, with the same command line options >>> (including the machine type). >>> >>> Right now your code obeys the first rule, not the second rule, so it >>> should add the device to the DSDT. >> >> Are you sure about selecting the DSDT? I don't see anyone else is using >> the ACPI_EXTRACT_NAME_* macros in the DSDT table (and I keep crashing my >> guest, but ignore it for now ;-)). > > There is one user: > > acpi-dsdt-isa.dsl: ACPI_EXTRACT_NAME_BYTE_CONST DSDT_APPLESMC_STA Found it after I've stopped looking only at the acpi-dsdt.dsl file. >>> BTW, which events would cause the ID to change? How should live cloning >>> (or revert to a disk+RAM snapshot) be implemented by layers above QEMU >>> for the VM gen ID to be patched? Can you add something to docs/ about >>> it? >> >> The VGID is expected to change when executing a VM with the -snapshot >> option, when a VM is restored from a backup or when it is imported, >> copied or cloned. So I would say it is a management's call. > > Ok, got it. > > So to support migration (which includes reverting to an earlier disk+RAM > snapshot) you just need to ensure the VGID is patched accordingly. > Whether VGID _will_ be different or not, that's management's call. > >> I think that the Microsoft's document describes the requirements better >> than me :-). >> >>> Also, how does this ID compare to the UUID in the DMI info (-uuid)? >> >> The -uuid is not expected to change after the VM was created. Unlike the >> -vmgenid that is designed to give the guest OS a notification that a >> change has occurred. Microsoft, as an example, writes that is can be use >> for a safer cryptographic software. > > I would say that cloning should change the UUID (and the VMGID). Again, that's a management call as well. One might choose not to change the BIOS UUID when cloning the machine in order to prevent Windows from trying to re-activate itself (or any other licensed software for that matter). > Paolo > A V2 of the patch was send to the list. Gal.