From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NKHo3-0006vR-SQ for qemu-devel@nongnu.org; Mon, 14 Dec 2009 15:46:11 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NKHnz-0006rh-0w for qemu-devel@nongnu.org; Mon, 14 Dec 2009 15:46:11 -0500 Received: from [199.232.76.173] (port=44646 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NKHny-0006rW-T7 for qemu-devel@nongnu.org; Mon, 14 Dec 2009 15:46:06 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51554) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NKHny-00023i-3t for qemu-devel@nongnu.org; Mon, 14 Dec 2009 15:46:06 -0500 Received: from int-mx08.intmail.prod.int.phx2.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id nBEKk4cg005115 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 14 Dec 2009 15:46:04 -0500 Date: Mon, 14 Dec 2009 22:43:19 +0200 From: "Michael S. Tsirkin" Subject: Re: [Qemu-devel] Re: [PATCH RFC] virtio: add features qdev property Message-ID: <20091214204319.GA6398@redhat.com> References: <4B261269.7080801@redhat.com> <20091214111046.GB32355@redhat.com> <4B262379.1060009@redhat.com> <20091214135915.GN973@redhat.com> <4B26534D.1060806@redhat.com> <20091214162342.GB5807@redhat.com> <4B267365.5090608@redhat.com> <20091214191742.GA6100@redhat.com> <4B26A2BC.6010501@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B26A2BC.6010501@redhat.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: Markus Armbruster , qemu-devel@nongnu.org On Mon, Dec 14, 2009 at 09:40:28PM +0100, Gerd Hoffmann wrote: > On 12/14/09 20:17, Michael S. Tsirkin wrote: >> On Mon, Dec 14, 2009 at 06:18:29PM +0100, Gerd Hoffmann wrote: >>> On 12/14/09 17:23, Michael S. Tsirkin wrote: >>>> On Mon, Dec 14, 2009 at 04:01:33PM +0100, Gerd Hoffmann wrote: >>>> So how do you do this? >>>> Assume we have -disable_hw_csum. >>>> We want new machine type to have it off, right? >>>> But now you run qemu on host which does >>>> not support hw_csum. With your suggestion >>>> it will not enable hw csum? >>> >>> I have trouble getting the setup you are talking about ... >>> >>> Sounds like hw_csum could be enabled/disabled depending on the hardware >>> capabilities on the host. Is that correct? >>> >>> cheers, >>> Gerd >> >> This currently depends on version of tun driver in the host. > > So this has nothing to do with -M pc-0.11 backward compatibility, right? Yes, this does. With 0.11 you must not expose this even if supported by host. Otherwise you wnt be able to migrate to 0.11. > You'll hit this when migrating 0.12 -> 0.12 with different host > kernels, right? And the common bit here is that both issues can be > handled by configuring virtio feature bits via properties, right? Yes. > What was the question again? > > cheers, > Gerd What do we put in e.g. 0.11 compat? Any features we enable there might not be supported by host. -- MST