Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933418AbbHJL05 (ORCPT ); Mon, 10 Aug 2015 07:26:57 -0400 Received: from smtp.citrix.com ([66.165.176.89]:32468 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932553AbbHJL0z (ORCPT ); Mon, 10 Aug 2015 07:26:55 -0400 X-IronPort-AV: E=Sophos;i="5.15,645,1432598400"; d="scan'208";a="289608157" Date: Mon, 10 Aug 2015 12:25:27 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Julien Grall CC: Stefano Stabellini , , , David Vrabel , , Boris Ostrovsky , Subject: Re: [Xen-devel] [PATCH v3 09/20] xen/biomerge: Don't allow biovec to be merge when Linux is not using 4KB page In-Reply-To: <55C889E4.8050307@citrix.com> Message-ID: References: <1438966019-19322-1-git-send-email-julien.grall@citrix.com> <1438966019-19322-10-git-send-email-julien.grall@citrix.com> <55C889E4.8050307@citrix.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1447 Lines: 36 On Mon, 10 Aug 2015, Julien Grall wrote: > Hi Stefano, > > On 10/08/15 11:50, Stefano Stabellini wrote: > > On Fri, 7 Aug 2015, Julien Grall wrote: > >> On ARM all dma-capable devices on a same platform may not be protected > >> by an IOMMU. The DMA requests have to use the BFN (i.e MFN on ARM) in > >> order to use correctly the device. > >> > >> While the DOM0 memory is allocated in a 1:1 fashion (PFN == MFN), grant > >> mapping will screw this contiguous mapping. > >> > >> When Linux is using 64KB page granularitary, the page may be split > >> accross multiple non-contiguous MFN (Xen is using 4KB page > >> granularity). Therefore a DMA request will likely fail. > >> > >> Checking that a 64KB page is using contiguous MFN is tedious. For > >> now, always says that biovec are not mergeable. > >> > >> Signed-off-by: Julien Grall > > > > Please fix the grammar in the subject line. > > If I made a mistake it's unlikely that I will find myself which one I made. > > Anyway, I guess you mean to replace merge by merged? I don't see any > other in the subject. yes and page/pages: xen/biomerge: Don't allow biovec's to be merged when Linux is not using 4KB pages -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/