From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: tap/bridge: Dropping NETIF_F_GSO/NETIF_F_SG Date: Mon, 16 May 2011 10:28:46 +0300 Message-ID: <20110516072846.GA6610@redhat.com> References: <20110504181813.GA17547@redhat.com> <20110505152644.GA8459@rere.qmqm.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org, Ben Hutchings , herbert@gondor.hengli.com.au To: =?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= Return-path: Received: from mx1.redhat.com ([209.132.183.28]:35742 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751806Ab1EPH2o (ORCPT ); Mon, 16 May 2011 03:28:44 -0400 Content-Disposition: inline In-Reply-To: <20110505152644.GA8459@rere.qmqm.pl> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, May 05, 2011 at 05:26:44PM +0200, Micha=C5=82 Miros=C5=82aw wro= te: > On Wed, May 04, 2011 at 09:18:14PM +0300, Michael S. Tsirkin wrote: > > BTW, I just noticed that net-next spits out > > many of the following when I run any VMs: > [...] > > tap0: Features changed: 0x40004040 -> 0x401b4849 >=20 > Before this message, userspace called ioctl(TIOCSETOFFLOAD) > turning offloads on. >=20 > > tap0: Dropping NETIF_F_SG since no checksum feature. > > tap0: Dropping NETIF_F_GSO since no SG feature. > > tap0: Features changed: 0x401b4849 -> 0x40004040 >=20 > And then it probably called ioctl(TIOCSETOFFLOAD) again, disabling th= em. >=20 > Best Regards, > Micha=C5=82 Miros=C5=82aw I'd have to look at this some more, but I know qemu-kvm supports offloads with current kernels. There seems to be some kernel behaviour change here. > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html