From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:37447)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1WIds3-0004Q0-Ec
	for qemu-devel@nongnu.org; Wed, 26 Feb 2014 07:46:01 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1WIdrx-0007rE-8G
	for qemu-devel@nongnu.org; Wed, 26 Feb 2014 07:45:55 -0500
Received: from mx1.redhat.com ([209.132.183.28]:52277)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1WIdrw-0007r8-Vi
	for qemu-devel@nongnu.org; Wed, 26 Feb 2014 07:45:49 -0500
Message-ID: <530DE1F2.6060701@redhat.com>
Date: Wed, 26 Feb 2014 13:45:38 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <cover.1392794450.git.hutao@cn.fujitsu.com>	<fad899d2a898a9a4b487fd27791b32dee6ddeaff.1392794450.git.hutao@cn.fujitsu.com>	<53047351.80300@redhat.com>	<20140219103657.4daed264@nial.usersys.redhat.com>	<20140226055706.GA5090@G08FNSTD100614.fnst.cn.fujitsu.com>	<20140226101056.1a9ec3b3@nial.usersys.redhat.com>	<530DC2FA.9080401@redhat.com>
	<20140226133119.3ccca5a3@nial.usersys.redhat.com>
In-Reply-To: <20140226133119.3ccca5a3@nial.usersys.redhat.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory
 backend ram fields
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: Igor Mammedov <imammedo@redhat.com>
Cc: Hu Tao <hutao@cn.fujitsu.com>, Marcelo Tosatti <mtosatti@redhat.com>, lersek@redhat.com, qemu-devel@nongnu.org, Wanlong Gao <gaowanlong@cn.fujitsu.com>

Il 26/02/2014 13:31, Igor Mammedov ha scritto:
>> > The problem is that some backends might not be handled the same way.
>> > For example, not all backends might produce a single void*/size_t pair
>> > for the entire region.  Think of a "composite" backend that produces a
>> > large memory region from two smaller ones.
> I'd prefer to keep backends simple, with 1:1 mapping to memory regions.

I agree.  However not all backends may have a mapping to a RAM memory 
region.  A composite backend could create a container memory region 
whose children are other HostMemoryBackend objects.

> Is there a need in composite one or something similar?

I've heard of users that want a node backed partially by hugetlbfs and 
partially by regular RAM.  Not sure why.

Paolo