From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH v3 05/13] xen/iommu: arm: Remove temporary the SMMU driver Date: Fri, 20 Feb 2015 13:47:55 +0000 Message-ID: <1424440075.30924.245.camel@citrix.com> References: <1422643768-23614-1-git-send-email-julien.grall@linaro.org> <1422643768-23614-6-git-send-email-julien.grall@linaro.org> <1424434719.30924.198.camel@citrix.com> <54E72E3E.5040703@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YOnwP-0001xH-Nk for xen-devel@lists.xenproject.org; Fri, 20 Feb 2015 13:48:25 +0000 In-Reply-To: <54E72E3E.5040703@linaro.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Julien Grall Cc: xen-devel@lists.xenproject.org, tim@xen.org, stefano.stabellini@citrix.com List-Id: xen-devel@lists.xenproject.org On Fri, 2015-02-20 at 12:53 +0000, Julien Grall wrote: > Hi Ian, > > On 20/02/15 12:18, Ian Campbell wrote: > > On Fri, 2015-01-30 at 18:49 +0000, Julien Grall wrote: > >> The current SMMU driver has completly diverged. That makes me hard to > >> maintain. > > > > Will this temporarily regress anything in a noticeable way? I think > > it'll just potentially make some hypothetical platform switch back to > > 1:1 dom0 mode, which in practice they all use anyway, IOW no harm done, > > even temporarily. So: > > We still have to keep the 1:1 DOM0 mapping with SMMU. It's because we > don't know if all devices are protected. > > The only possible regression is the SMMU node won't be remove from DOM0 > and threfore may be used by Linux. Aside that there is no different for > the user. Might that cause issues? The main thing I'm worried about is if the bisector is searching a range which includes this change looking for some unrelated change and this commit causes some sort of spurious issue or perturbation which confuses the bisector. Perhaps a temporary stub could be put in which just marks SMMUs as used by Xen but doesn't actually use them? > >> Signed-off-by: Julien Grall > >> Acked-by: Stefano Stabellini > > > > Acked-by: Ian Campbell > > Regards, >