WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] Re: [kvm-devel] [PATCH RFC 3/3] virtio infrastructure: examp

To: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: [kvm-devel] [PATCH RFC 3/3] virtio infrastructure: example block driver
From: Carsten Otte <cotte@xxxxxxxxxx>
Date: Thu, 31 May 2007 14:57:27 +0200
Cc: Jimi Xenidis <jimix@xxxxxxxxxxxxxx>, Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>, Xen Mailing List <xen-devel@xxxxxxxxxxxxxxxxxxx>, "jmk@xxxxxxxxxxxxxxxxxxx" <jmk@xxxxxxxxxxxxxxxxxxx>, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>, kvm-devel <kvm-devel@xxxxxxxxxxxxxxxxxxxxx>, mschwid2@xxxxxxxxxxxxxxxxxx, virtualization <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Christian Borntraeger <cborntra@xxxxxxxxxx>, Suzanne McIntosh <skranjac@xxxxxxxxxx>
Delivery-date: Thu, 31 May 2007 10:28:33 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <1180614091.11133.63.camel@xxxxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Organization: IBM Deutschland Entwicklung GmbH,Vorsitzender des Aufsichtsrats: Johann Weihen,Geschäftsführung: Herbert Kircher,Sitz der Gesellschaft: Böblingen,Registergericht: Amtsgericht Stuttgart, HRB 243294
References: <1180613947.11133.58.camel@xxxxxxxxxxxxxxxxxxxxx> <1180614044.11133.61.camel@xxxxxxxxxxxxxxxxxxxxx> <1180614091.11133.63.camel@xxxxxxxxxxxxxxxxxxxxx>
Reply-to: carsteno@xxxxxxxxxx
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mozilla-Thunderbird 2.0.0.0 (X11/20070521)
Rusty Russell wrote:
Example block driver using virtio.

The block driver uses outbufs with sg[0] being the request information
(struct virtio_blk_outhdr) with the type, sector and inbuf id.  For a
write, the rest of the sg will contain the data to be written.

The first segment of the inbuf is a result code (struct
virtio_blk_inhdr).  For a read, the rest of the sg points to the input
buffer.

TODO:
        1) Ordered tag support.
Implementing a do_request function has quite a few disadvantages over hooking into q->make_request_fn. This way, we have the device plug (latency), request merging, and I/O scheduling inside the guest. It seems preferable to do that in the host, especially when requests of multiple guests end up on the same physical media (shared access, or partitioned).

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel