From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: [PATCH v2] xen: arm: process XENMEM_add_to_physmap_range forwards not backwards. Date: Wed, 18 Dec 2013 14:11:03 +0000 Message-ID: <52B1ACF7.4080007@eu.citrix.com> References: <1387373954-31668-1-git-send-email-ian.campbell@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1387373954-31668-1-git-send-email-ian.campbell@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell , xen-devel@lists.xen.org Cc: stefano.stabellini@eu.citrix.com, julien.grall@linaro.org, tim@xen.org, george.dunlap@citrix.com, Jan Beulich List-Id: xen-devel@lists.xenproject.org On 12/18/2013 01:39 PM, Ian Campbell wrote: > Jan points out that processing the list backwards is rather counter intuitive > and that the effect of the hypercall can differ between forwards and backwards > processing (e.g. in the presence of duplicate idx or gpfn, which would be > unusualy but as Jan says, users are a creative bunch) > > Signed-off-by: Ian Campbell > Cc: Jan Beulich > Cc: Mukesh Rathor > --- > v2: Remember to crank the errs array too. > > Resending despite abuse of overwriting the IN paramters, since coming to > rely on backwards processing is a harder hole to get out of than going > from modifying the strict to not. > > Release: subtle ABI change, should go in to 4.4 before people rely on it (they > are not relying on it today TTBOMK and it seems unlikely but lets not risk it) Yes, I agree: the risk of having to work around a bad ABI indefinitely is worse than the relatively small risk of finding a bug in this and then fixing it. Release-acked-by: George Dunlap -George