Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753576AbaJBQm2 (ORCPT ); Thu, 2 Oct 2014 12:42:28 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:49441 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751497AbaJBQm1 (ORCPT ); Thu, 2 Oct 2014 12:42:27 -0400 Date: Thu, 2 Oct 2014 12:41:21 -0400 From: Konrad Rzeszutek Wilk To: Peter Hurley Cc: Thomas Gleixner , Akinobu Mita , LKML , Andrew Morton , Marek Szyprowski , David Woodhouse , Don Dutile , Ingo Molnar , "H. Peter Anvin" , Andi Kleen , x86@kernel.org, iommu@lists.linux-foundation.org, Greg KH Subject: Re: [PATCH v3 0/5] enhance DMA CMA on x86 Message-ID: <20141002164121.GF1715@laptop.dumpdata.com> References: <1397567329-3771-1-git-send-email-akinobu.mita@gmail.com> <5426CA0A.7000806@hurleysoftware.com> <54294C0B.1060705@hurleysoftware.com> <542ABF77.1020402@hurleysoftware.com> <542B5DC2.8020806@hurleysoftware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <542B5DC2.8020806@hurleysoftware.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-Source-IP: acsinet21.oracle.com [141.146.126.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 30, 2014 at 09:49:54PM -0400, Peter Hurley wrote: > On 09/30/2014 07:45 PM, Thomas Gleixner wrote: > > Whether the proposed patchset is the correct solution to support it is > > a completely different question. > > This patchset has been in mainline since 3.16 and has already caused > regressions, so the question of whether this is the correct solution has > already been answered. > > > So either you stop this right now and help Akinobu to find the proper > > solution > > If this is only a test platform for ARM parts then I don't think it > unreasonable to suggest forking x86 swiotlb support into a iommu=cma Not sure what you mean by 'forking x86 swiotlb' ? As in have SWIOTLB work under ARM? > selector that gets DMA mapping working for this test platform and doesn't > cause a bunch of breakage. I think you might want to take a look at the IOMMU_DETECT macros and enable CMA there only if the certain devices are available. That way the normal flow of detecting which IOMMU to use is still present and will turn of CMA if there is no device that would use it. > > Which is different than if the plan is to ship production units for x86; > then a general purpose solution will be required. > > As to the good design of a general purpose solution for allocating and > mapping huge order pages, you are certainly more qualified to help Akinobu > than I am. > > Regards, > Peter Hurley > -- 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/