From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: Xen Project policy on feature flags Date: Mon, 29 Sep 2014 10:00:13 +0100 Message-ID: <54291F9D.4030705@eu.citrix.com> References: <542588A90200007800039B3E@mail.emea.novell.com> <1411741172.26149.75.camel@kazak.uk.xensource.com> <20140926142959.GA19421@laptop.dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Stefano Stabellini , Konrad Rzeszutek Wilk Cc: xen-devel@lists.xensource.com, keir@xen.org, Tim Deegan , Ian Jackson , Lars Kurth , DavidVrabel , Jan Beulich , Ian Campbell List-Id: xen-devel@lists.xenproject.org On 09/26/2014 03:49 PM, Stefano Stabellini wrote: >> Let me rephrase - will it boot in the same fashion (And with the same >> bugs) as it did prior to this functionality being introduced? > 3.15 -> dom0 on ARM broken (if netback is used) > 3.17 -> dom0 on ARM is fixed, only if the kernel is compiled with CONFIG_ARM_LPAE > > Reverting the XENFEAT_grant_map_identity related changes would give you > a system broken even with CONFIG_ARM_LPAE. > Reverting Zoltan's changes to netback would give you a working system. So the *only* reason to include this flag at this point is to allow people to run an unmodified 3.17 kernel with netback, is that right? It seems like a really jerk move to encourage people to put 3.17 on their systems, and then deliberately break it on a subsequent release. Particularly with ARM, where people are used to doing platform-specific things, it seems like encouraging people to either use pre-3.15 or to revert Zoltan's changes would be a better option. -George