From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH] kvm tools: virtio-net mergable rx buffers Date: Wed, 24 Apr 2013 12:23:28 +0300 Message-ID: <20130424092328.GC11245@redhat.com> References: <1366677147-2150-1-git-send-email-sasha.levin@oracle.com> <51774894.7080008@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Sasha Levin , Eric Northup , Will Deacon , Marc Zyngier , KVM , Asias He , jasowang@redhat.com, Rusty Russell To: Pekka Enberg Return-path: Received: from mx1.redhat.com ([209.132.183.28]:10199 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752166Ab3DXJcu (ORCPT ); Wed, 24 Apr 2013 05:32:50 -0400 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Apr 24, 2013 at 09:51:57AM +0300, Pekka Enberg wrote: > Hi, > > On 04/23/2013 12:35 PM, Eric Northup wrote: > >> Do you care about guests with drivers that don't negotiate > >> VIRTIO_NET_F_MRG_RXBUF? > > On Wed, Apr 24, 2013 at 5:51 AM, Sasha Levin wrote: > > We usually try to keep backward compatibility, but in this case > > mergable RX buffers are about 5 years old now, so it's safe to > > assume they'll be running in any guest. > > > > Unless there is a specific reason to allow working without them > > I'd rather keep the code simple in this case. > > Are there such guests around? What's the failure scenario for them > after this patch? > > Pekka Warning: have not looked at the patch, just a general comment. I think it's reasonable to assume embedded guests such as PXE won't negotiate any features. And, running old guests is one of the reasons people use virtualization at all. So 5 years is not a lot. In any case, stick to the device spec please, if you want it changed please send a spec patch, don't deviate from it randomly. -- MST