From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:44318)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1SoA2O-0003xF-RH
	for qemu-devel@nongnu.org; Mon, 09 Jul 2012 05:13:54 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1SoA2M-00034H-Lp
	for qemu-devel@nongnu.org; Mon, 09 Jul 2012 05:13:48 -0400
Received: from mx1.redhat.com ([209.132.183.28]:12894)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1SoA2M-00033P-DQ
	for qemu-devel@nongnu.org; Mon, 09 Jul 2012 05:13:46 -0400
Message-ID: <4FFAA0C3.3080703@redhat.com>
Date: Mon, 09 Jul 2012 11:13:39 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <4FFA9C30.2070201@linux.vnet.ibm.com>
In-Reply-To: <4FFA9C30.2070201@linux.vnet.ibm.com>
Content-Type: text/plain; charset=GB2312
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [RFC] introduce a dynamic library to expose qemu
 block API
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, qemu-devel@nongnu.org

Il 09/07/2012 10:54, Wenchao Xia ha scritto:
> Following is my implementing plan draft:
>   1 introduce libqblock.so in sub directory in qemu.
>   2 write a nbd client in libqblock, similar to qemu nbd client. Then
> use it to talk with nbd server, by default is qemu-nbd, to get access
> to images. In this way, libqblock.so could be friendly LGPL licensed.

Did you actually assess the license situation of the block layer?
block.c and large parts of block/* are under a BSD license, for example.
 If the library only has to support raw files, it might do so using
synchronous I/O only.  This would remove a large body of GPL-licensed code.

>   3 still not got a good way to get additional info in (2)(3)(4),
> currently in my head is patch qemu-nbd to add an additional nbd command,
> "image-info", in which returns related info.

On the Linux kernel mailing list I would have no qualms labeling such
command as "crap".  However, since the social standards on qemu-devel
are a bit higher, I'll ask instead: what information would the command
provide beyond the size?

Paolo