From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37720) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZbUcQ-0003CZ-Hf for qemu-devel@nongnu.org; Mon, 14 Sep 2015 10:20:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZbUcM-0006vu-4T for qemu-devel@nongnu.org; Mon, 14 Sep 2015 10:20:30 -0400 From: Alberto Garcia In-Reply-To: <20150914084555.GB3550@noname.str.redhat.com> References: <1be64a26c9a89ff0af4c2b1299d6c8b58361644a.1441890725.git.berto@igalia.com> <55F30DA8.4070502@redhat.com> <20150911172854.GC5164@noname.redhat.com> <55F31075.7090101@redhat.com> <20150914084555.GB3550@noname.str.redhat.com> Date: Mon, 14 Sep 2015 16:20:12 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Subject: Re: [Qemu-devel] [PATCH v3 2/4] block: Add 'ignore-backing' field to BlockdevOptionsGenericCOWFormat List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: Stefan Hajnoczi , qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz On Mon 14 Sep 2015 10:45:55 AM CEST, Kevin Wolf wrote: >> >>> So why do we need the new flag? Because "backing: ''" is ugly? >> >> Anyway, was this ever implemented? It seems that passing a string to >> the 'backing' parameter is only specified in the JSON schema, but no >> one actually uses that. >> > I have a patch that actually allows passing a node-name reference as a > string here. v1 was posted a few months ago; it just turned out that I > need to kill bdrv_swap() before that can work because bdrv_swap() > doesn't work with nodes that have a BlockBackend attached. But there was no way to open a BDS without having a BlockBackend attached, or was there? It's possible with Max's "BlockBackend and media" series, that's why I am using it. Berto