From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: xen-netback: make feature-rx-notify mandatory -- Breaks stubdoms Date: Wed, 10 Dec 2014 14:12:19 +0000 Message-ID: <548854C3.7060008@citrix.com> References: <54884DA8.7030003@nuclearfallout.net> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Cc: "Xen-devel@lists.xen.org" , Ian Campbell , Wei Liu , "netdev@vger.kernel.org" To: John Return-path: Received: from smtp.citrix.com ([66.165.176.89]:8386 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753874AbaLJOMW (ORCPT ); Wed, 10 Dec 2014 09:12:22 -0500 In-Reply-To: <54884DA8.7030003@nuclearfallout.net> Sender: netdev-owner@vger.kernel.org List-ID: On 10/12/14 13:42, John wrote: > David, > > This patch you put into 3.18.0 appears to break the latest version of > stubdomains. I found this out today when I tried to update a machine to > 3.18.0 and all of the domUs crashed on start with the dmesg output like > this: Cc'ing the lists and relevant netback maintainers. I guess the stubdoms are using minios's netfront? This is something I forgot about when deciding if it was ok to make this feature mandatory. The patch cannot be reverted as it's a prerequisite for a critical (security) bug fix. I am also unconvinced that the no-feature-rx-notify support worked correctly anyway. This can be resolved by: - Fixing minios's netfront to support feature-rx-notify. This should be easy but wouldn't help existing Xen deployments. Or: - Reimplement feature-rx-notify support. I think the easiest way is to queue packets on the guest Rx internal queue with a short expiry time. > [ 83.045785] device vif2.0 entered promiscuous mode > [ 83.059220] vif vif-2-0: 22 feature-rx-notify is mandatory > [ 83.060763] vif vif-2-0: 1 mapping in shared page 2047 from domain 2 > [ 83.060861] vif vif-2-0: 1 mapping shared-frames 2047/2046 port tx 4 > rx 4 > > This is on the very latest patched version of 4.4. David