From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53357) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1axaEk-0002Fb-0n for qemu-devel@nongnu.org; Tue, 03 May 2016 09:19:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1axaEX-0000Ql-PR for qemu-devel@nongnu.org; Tue, 03 May 2016 09:19:32 -0400 Date: Tue, 3 May 2016 15:18:39 +0200 From: Kevin Wolf Message-ID: <20160503131839.GD3917@noname.str.redhat.com> References: <20160429151107.GL4350@noname.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH v9 07/11] block: Add QMP support for streaming to an intermediate layer List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alberto Garcia Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz , Eric Blake , Stefan Hajnoczi Am 03.05.2016 um 14:53 hat Alberto Garcia geschrieben: > On Fri 29 Apr 2016 05:11:07 PM CEST, Kevin Wolf wrote: > >> + if (active == NULL) { > >> + error_setg(errp, "Cannot find top level node for '%s'", device); > >> + goto out; > >> + } > > > > Hm... On the one hand, I really like that you don't expect the user to > > provide the active layer in QMP. This allows us to remove this wart > > once we have the new op blockers. > > Exactly, I still plan to stick to the API we discussed last year. > > > On the other hand, this code assumes that there is only a single > > top-level node. This isn't necessarily true any more these days. > > Hmm... if you give me an example I can test that scenario. Simply reference the same node twice: $ x86_64-softmmu/qemu-system-x86_64 \ -drive if=none,file=/tmp/backing.qcow2,id=backing \ -drive file=/tmp/test.qcow2,backing=backing,id=hda \ -drive file=/tmp/test2.qcow2,backing=backing,id=hdb If backing.qcow2 has another backing file, you can do the intermediate streaming to it and both hda and hdb are active layers on top of it. Kevin