From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34703) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fLt3G-000827-7Z for qemu-devel@nongnu.org; Thu, 24 May 2018 12:25:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fLt3C-0002Jy-7t for qemu-devel@nongnu.org; Thu, 24 May 2018 12:25:18 -0400 From: Markus Armbruster References: <20180518180440-mutt-send-email-mst@kernel.org> <20180524113251.GB4660@redhat.com> <20180524174603-mutt-send-email-mst@kernel.org> <20180524150817.GF4008@localhost.localdomain> <20180524152014.GW2209@redhat.com> Date: Thu, 24 May 2018 18:25:05 +0200 In-Reply-To: <20180524152014.GW2209@redhat.com> (Richard W. M. Jones's message of "Thu, 24 May 2018 16:20:14 +0100") Message-ID: <87y3g9yqam.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] storing machine data in qcow images? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Richard W.M. Jones" Cc: Kevin Wolf , ehabkost@redhat.com, qemu-block@nongnu.org, "Michael S. Tsirkin" , qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com "Richard W.M. Jones" writes: > On Thu, May 24, 2018 at 05:08:17PM +0200, Kevin Wolf wrote: >> Am 24.05.2018 um 16:56 hat Michael S. Tsirkin geschrieben: >> > On Thu, May 24, 2018 at 12:32:51PM +0100, Richard W.M. Jones wrote: >> > > There is however a seed of a good idea in the thread: >> > > >> > > > I don't think QEMU needs to use this information automatically, >> > > > necessarily. I think the first step is to simply make QEMU save >> > > > this information in the disk image, and making qemu-img able to >> > > > read and write this information. >> > > >> > > It would be nice if qcow2 added arbitrary data sections (which would >> > > always be ignored by qemu) for storing additional data. This could be >> > > used to create a compact qcow2 + metadata format to rival OVA for >> > > management layers to use, and there are various other uses too. >> > > >> > > Rich. >> > >> > I think this part is pretty uncontroversial. >> > >> > But can we add data without changing the verion? >> >> Yes. Don't worry about where to store it, we'll solve this. Do worry >> about what to store. > > Ideally from my point of view: named blobs. More formally, any number > of (key, value) pairs where the key is a simple string, and the value > is a binary blob. The binary blobs might really be XML or YAML or an > icon or whatever, but qemu would not need to look inside them. > > We could then attach metadata (in some to-be-decided format) to qcow2 > files and create a compact rival to OVA without needing to encode any > knowledge of the metadata into qemu at all. > > Another use for this is allowing qcow2 files to contain names, titles, > descriptions, creation date, OS icons, etc. which could be displayed > in file managers. Have we just reinvented resource forks? SCNR ;)