From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [RFC for-4.5 12/12] drivers/passthrough: arm: Add support for SMMU drivers Date: Thu, 20 Feb 2014 11:05:27 +0000 Message-ID: <5305E177.7080800@linaro.org> References: <1391794991-5919-1-git-send-email-julien.grall@linaro.org> <1391794991-5919-13-git-send-email-julien.grall@linaro.org> <1392819327.29739.85.camel@kazak.uk.xensource.com> <5304E81A.3050703@linaro.org> <1392830820.29739.97.camel@kazak.uk.xensource.com> <5304EA5B.50506@linaro.org> <5305C6B9020000780011DEC9@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WGRRc-0000Ql-Au for xen-devel@lists.xenproject.org; Thu, 20 Feb 2014 11:05:32 +0000 Received: by mail-we0-f174.google.com with SMTP id w61so1351083wes.33 for ; Thu, 20 Feb 2014 03:05:30 -0800 (PST) In-Reply-To: <5305C6B9020000780011DEC9@nat28.tlf.novell.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: Jan Beulich Cc: Ian Campbell , patches@linaro.org, tim@xen.org, stefano.stabellini@citrix.com, xen-devel@lists.xenproject.org, Xiantao Zhang List-Id: xen-devel@lists.xenproject.org Hello Jan, On 20/02/14 08:11, Jan Beulich wrote: >>>> On 19.02.14 at 18:31, Julien Grall wrote: >> On 02/19/2014 05:27 PM, Ian Campbell wrote: >>> On Wed, 2014-02-19 at 17:21 +0000, Julien Grall wrote: >>>>>> +#define SZ_4K (1 << 12) >>>>>> +#define SZ_64K (1 << 16) >>>>>> + >>>>>> +/* Driver options */ >>>>>> +#define SMMU_OPT_SECURE_CONFIG_ACCESS (1 << 0) >>>>> >>>>> Is this just retained to reduce the deviation from the Linux driver? >>>>> It's no use to us I think. (I suppose that goes for a bunch of other >>>>> stuff, eg.. the PGSZ_4K stuff, which I will avoid commenting on >>>>> further). >>>> >>>> SZ_4K and SZ_64K is used later in the code. >>> >>> But they are actually useless to us aren't they? >> >> As we use only 4K page in Xen yes. I kept it because there is few place >> where the SMMU configuration is not the same. >> >> If we want to support 64K page in the future it will harder to had >> support if this stuff is removed. >> >> The constant was added by himself as it doesn't exists on Xen. I can >> move it into the generic code. > > But if possible I'd like to encourage you using PAGE_SIZE_4K to > match up with what we already got in the IOMMU code. Unless > deviation from the sources you're cloning is deemed worse than > consistency within our code. I think this change is fine. It doesn't fundamentally change the code. I will update the patch for the next version. Regards, -- Julien Grall