From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42156) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aRJeA-0002Qm-Pb for qemu-devel@nongnu.org; Thu, 04 Feb 2016 08:08:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aRJe9-0002us-R7 for qemu-devel@nongnu.org; Thu, 04 Feb 2016 08:08:30 -0500 Date: Thu, 4 Feb 2016 14:08:23 +0100 From: Kevin Wolf Message-ID: <20160204130823.GC2314@noname> References: <1454517196-4560-1-git-send-email-mreitz@redhat.com> <1454517196-4560-3-git-send-email-mreitz@redhat.com> <20160203170609.GR30222@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160203170609.GR30222@redhat.com> Subject: Re: [Qemu-devel] [PATCH 2/2] qapi: Allow blockdev-add for NBD List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: Markus Armbruster , Paolo Bonzini , qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz Am 03.02.2016 um 18:06 hat Daniel P. Berrange geschrieben: > On Wed, Feb 03, 2016 at 05:33:16PM +0100, Max Reitz wrote: > > We have to introduce a new object (BlockdevOptionsNbd) for several > > reasons: > > - Neither of InetSocketAddress nor UnixSocketAddress alone is > > sufficient, because both are supported > > - We cannot use SocketAddress because NBD does not support an fd, > > and because it is not a flat union which BlockdevOptionsNbd is > > With my patch series that converts NBD to use QIOChannel, all the > entry points for client & server *do* take a SocketAddress struct > to provide address info. So internally the code does in fact allow > use of an FD, if there were a way to specify it a the QAPI level... > > eg see > > https://lists.gnu.org/archive/html/qemu-devel/2016-01/msg04159.html That's patch 1 of a series that has a few more dependencies. Can the patch be applied without the rest of the series (and without the dependencies) so that we don't have to wait for a very long time with Max's patches? > > - We cannot use a flat union of InetSocketAddress and > > UnixSocketAddress because we would need some kind of discriminator > > which we do not have; we could inline the UnixSocketAddress as a > > string and then make it an 'alternate' type instead of a union, but > > this will not work either, because: > > - InetSocketAddress itself is not suitable for NBD because the port is > > not optional (which it is for NBD) and because it offers more options > > (like choosing between ipv4 and ipv6) which NBD does not support. > > The *should* support ipv4 and ipv6 options for NBD. We should also make > the port optional in the SocketAddress struct - I tried to do that previously > but my patch was flawed, but we should revisit this. > > So IMHO all the things you list above are reasons *for* using SocketAddress > and not re-inventing it poorly with explicit host + port fields. Agreed. Anything in SocketAddress that isn't supported is either a bug or a missing feature. Kevin