From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1Kxj96-0008GX-6k
	for qemu-devel@nongnu.org; Wed, 05 Nov 2008 09:14:08 -0500
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1Kxj94-0008Fr-P4
	for qemu-devel@nongnu.org; Wed, 05 Nov 2008 09:14:07 -0500
Received: from [199.232.76.173] (port=42291 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1Kxj94-0008Fm-II
	for qemu-devel@nongnu.org; Wed, 05 Nov 2008 09:14:06 -0500
Received: from qw-out-1920.google.com ([74.125.92.146]:47245)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <anthony@codemonkey.ws>) id 1Kxj94-00059F-CZ
	for qemu-devel@nongnu.org; Wed, 05 Nov 2008 09:14:06 -0500
Received: by qw-out-1920.google.com with SMTP id 5so6625qwc.4
	for <qemu-devel@nongnu.org>; Wed, 05 Nov 2008 06:14:04 -0800 (PST)
Message-ID: <4911AA29.1090101@codemonkey.ws>
Date: Wed, 05 Nov 2008 08:14:01 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] Live migration - exec: support to be reintroduced?
References: <geqq17$om7$1@ger.gmane.org>
	<49113157.3090101@codemonkey.ws>	<20081105100546.GA25523@redhat.com>
	<491199A2.1040207@redhat.com>
In-Reply-To: <491199A2.1040207@redhat.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Reply-To: qemu-devel@nongnu.org
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: qemu-devel@nongnu.org

Avi Kivity wrote:
> Daniel P. Berrange wrote:
>> We used it to implement save-to-file, exec'ing 'dd'. I'd rather prefer
>> that we had a more explicit 'migrate to a file' capability rather than
>> the hack of execing dd.
>>   
>
> (qemu) acceptfd blah
> receives an file descriptor from the monitor using SCM_RIGHTS and 
> assigns it to the tag 'blah'
> (qemu) migrate fd:blah
> migrates to the fd denominated by the tag 'blah'
> (qemu) closefd blah

This could be generally useful for other things too (like char device 
redirection).

I'm not sure how many people would really use it though, you're talking 
about serious unix-fu here.

Regards,

Anthony Liguori

> You can use literal numbers instead of tags to refer to file 
> descriptors inherited from the environment:
>
> (qemu) migrate fd:17
>