From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH v4 19/21] xen/arm: grant: Add another entry to map MFN 1:1 in dom0 p2m Date: Mon, 28 Apr 2014 15:47:21 +0100 Message-ID: <535E69F9.10404@linaro.org> References: <1398172475-27873-1-git-send-email-julien.grall@linaro.org> <1398172475-27873-20-git-send-email-julien.grall@linaro.org> <1398694316.29700.128.camel@kazak.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" 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 1Wemq5-0007Ga-JG for xen-devel@lists.xenproject.org; Mon, 28 Apr 2014 14:47:25 +0000 Received: by mail-ee0-f51.google.com with SMTP id c13so4967510eek.38 for ; Mon, 28 Apr 2014 07:47:23 -0700 (PDT) In-Reply-To: <1398694316.29700.128.camel@kazak.uk.xensource.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 Cc: xen-devel@lists.xenproject.org, tim@xen.org, stefano.stabellini@citrix.com List-Id: xen-devel@lists.xenproject.org On 04/28/2014 03:11 PM, Ian Campbell wrote: > On Tue, 2014-04-22 at 14:14 +0100, Julien Grall wrote: >> Grant mapping can be used for DMA request. The dev_bus_addr returned by the >> hypercall is the MFN (not the IPA). Currently Linux is using this address (via >> swiotlb) to program the DMA. >> When the device is protected by IOMMU the request will fail. We have to >> add 1:1 mapping in the domain p2m to allow DMA request working. >> >> This is valid because DOM0 has its memory mapped 1:1. > Go on to say: > > ... and therefore we know that RAM and devices cannot clash (or > something). Your sentence sounds good. I will update the commit message with it. >> Signed-off-by: Julien Grall > > With that: Acked-by: Ian Campbell Thanks! -- Julien Grall