From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:43595)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1X1cgh-0003B7-5i
	for qemu-devel@nongnu.org; Mon, 30 Jun 2014 10:36:16 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1X1cgY-0003Ry-5J
	for qemu-devel@nongnu.org; Mon, 30 Jun 2014 10:36:07 -0400
Received: from mail-wi0-x22c.google.com ([2a00:1450:400c:c05::22c]:59834)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1X1cgX-0003Rf-Ui
	for qemu-devel@nongnu.org; Mon, 30 Jun 2014 10:35:58 -0400
Received: by mail-wi0-f172.google.com with SMTP id hi2so6179447wib.17
	for <qemu-devel@nongnu.org>; Mon, 30 Jun 2014 07:35:57 -0700 (PDT)
Sender: Paolo Bonzini <paolo.bonzini@gmail.com>
Message-ID: <53B175C9.3070806@redhat.com>
Date: Mon, 30 Jun 2014 16:35:53 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <CACtCCo8YTsg6sgWB3YjYYk8AHokw0mLNvEMfkoa5Dg6=tokugA@mail.gmail.com>	<53ADE6F8.1070303@redhat.com>	<CACtCCo-QTDp72ZNDvk2rWUaA7bAv+6tTCo2jFqvFYKDObOVGqQ@mail.gmail.com>	<53B14064.8010600@redhat.com>
	<CACtCCo85ftTWMPDVZ20Pdq_URKH2fTCeaeQ3TzKtN1-qsZotZA@mail.gmail.com>
In-Reply-To: <CACtCCo85ftTWMPDVZ20Pdq_URKH2fTCeaeQ3TzKtN1-qsZotZA@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] The first function called after migration for a
	block device
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: Xiongzi Ge <gexxx132@umn.edu>
Cc: qemu-devel@nongnu.org

Il 30/06/2014 16:03, Xiongzi Ge ha scritto:
> I tried. It invalidated the cache of the block device after migration.

It didn't invalidate anything in the guest, and there's *NO WAY* 
absolutely for QEMU to influence the cache in the guest.

Again: all you can do is use O_DIRECT in the guest.

> So, here, we can use a new cache for the block device after migration.

I don't understand what you mean.

> Is it right?  I can implement a simple block driver in block/ directory.

Probably not.

Paolo