From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [PATCH] Work around dhclient brokenness Date: Tue, 19 Aug 2008 14:41:01 +1000 Message-ID: <200808191441.01882.rusty@rustcorp.com.au> References: <1218829632-19037-1-git-send-email-aliguori@us.ibm.com> <200808191045.20980.rusty@rustcorp.com.au> <20080819031757.GA6468@puku.stupidest.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Herbert Xu , Avi Kivity , Anthony Liguori , kvm@vger.kernel.org, Mark McLoughlin To: Chris Wedgwood Return-path: Received: from ozlabs.org ([203.10.76.45]:37127 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754158AbYHSEnd (ORCPT ); Tue, 19 Aug 2008 00:43:33 -0400 In-Reply-To: <20080819031757.GA6468@puku.stupidest.org> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: On Tuesday 19 August 2008 13:17:57 Chris Wedgwood wrote: > On Tue, Aug 19, 2008 at 10:45:20AM +1000, Rusty Russell wrote: > > For those not following closely: We already have a method for the > > guest to accept or reject features. Our problem is that the guest > > is already accepting the CSUM feature: but one critical userspace > > app (dhcp-client) can't actually handle it due to a bug. > > Can't we just get dhcp-client client fixed upstream and let the > distro's update in a couple of months? Herbert has already fixed the client, but it seems upstream hasn't released yet. > > The proposal is to add another mechanism, whereby the host doesn't > > advertise CSUM, but advertises a new CSUM2 feature. The driver > > doesn't accept this by default: then guest userspace says "hey, I > > *really can* handle CSUM". This would have to be done dby resetting > > the device in the ethtool callback (that's how we renegotiate > > features). And guests need a special virtio hack in their init > > scripts. > > If guest can have modified scripts for virtio and what not, they can > have a fixed dhcp-client. They need to do both. This way if they don't, it still works, but networking is at a penalty (no CSUM offload). Rusty.