From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47753) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cTUxX-0001Yv-DM for qemu-devel@nongnu.org; Tue, 17 Jan 2017 09:42:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cTUxS-00016m-IL for qemu-devel@nongnu.org; Tue, 17 Jan 2017 09:42:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48852) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cTUxS-00016Z-CP for qemu-devel@nongnu.org; Tue, 17 Jan 2017 09:41:58 -0500 Date: Tue, 17 Jan 2017 16:41:57 +0200 From: "Michael S. Tsirkin" Message-ID: <20170117163848-mutt-send-email-mst@kernel.org> References: <20170117140058.166de8c2@nial.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170117140058.166de8c2@nial.brq.redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 3/6] ACPI: Add Virtual Machine Generation ID support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Igor Mammedov Cc: ben@skyportsystems.com, qemu-devel@nongnu.org, Laszlo Ersek , Gerd Hoffmann On Tue, Jan 17, 2017 at 02:00:58PM +0100, Igor Mammedov wrote: > Question is how you'd get address of it and I think that's where > writable fwcfg files come in play. > I'd prefer fwcfg_loader in firmware to write it back after buffer > allocation is done as it's already has utilities for fw_cfg, > but that probably would mean extending loader protocol to support > new writeback command. Right. It's quite easy to do as at least seabios was written to ignore commands it does not recognize. So with old bios you just don't get a write. Not sure about UEFI, worth checking. > PS, address one would get from guest should be migrated as well IIRC writeable fw cfg blobs are migrated automatically. -- MST