Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751813AbaKEWB4 (ORCPT ); Wed, 5 Nov 2014 17:01:56 -0500 Received: from mail-la0-f42.google.com ([209.85.215.42]:48628 "EHLO mail-la0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751219AbaKEWBx convert rfc822-to-8bit (ORCPT ); Wed, 5 Nov 2014 17:01:53 -0500 From: Michal Nazarewicz To: Weijie Yang , Gregory Fong Cc: linux-mm@kvack.org, Laura Abbott , iamjoonsoo.kim@lge.com, Marek Szyprowski , "linux-kernel\@vger.kernel.org" , Florian Fainelli , Brian Norris Subject: Re: CMA alignment question In-Reply-To: Organization: http://mina86.com/ References: User-Agent: Notmuch/0.17+15~gb65ca8e (http://notmuchmail.org) Emacs/25.0.50.1 (x86_64-unknown-linux-gnu) X-Face: PbkBB1w#)bOqd`iCe"Ds{e+!C7`pkC9a|f)Qo^BMQvy\q5x3?vDQJeN(DS?|-^$uMti[3D*#^_Ts"pU$jBQLq~Ud6iNwAw_r_o_4]|JO?]}P_}Nc&"p#D(ZgUb4uCNPe7~a[DbPG0T~!&c.y$Ur,=N4RT>]dNpd;KFrfMCylc}gc??'U2j,!8%xdD Face: 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 X-PGP: 50751FF4 X-PGP-FP: AC1F 5F5C D418 88F8 CC84 5858 2060 4012 5075 1FF4 X-Hashcash: 1:20:141105:m.szyprowski@samsung.com::/RmCDym6P+6MMC/K:0000000000000000000000000000000000000085+ X-Hashcash: 1:20:141105:iamjoonsoo.kim@lge.com::jJ1TBS/VKR3WKjRR:0000000000000000000000000000000000000001aM7 X-Hashcash: 1:20:141105:lauraa@codeaurora.org::vnuRBScpsXNmW4m7:00000000000000000000000000000000000000001qHG X-Hashcash: 1:20:141105:computersforpeace@gmail.com::jtoaP8m7WiRITmH1:000000000000000000000000000000000028nR X-Hashcash: 1:20:141105:f.fainelli@gmail.com::AToVKL/RlhpDMfCd:000000000000000000000000000000000000000002Ku9 X-Hashcash: 1:20:141105:weijie.yang.kh@gmail.com::BpS1TlfvWYL7RgHA:00000000000000000000000000000000000004Zsq X-Hashcash: 1:20:141105:linux-mm@kvack.org::3UVVGOd84o/eMvzC:00000000000000000000000000000000000000000003fsR X-Hashcash: 1:20:141105:gregory.0xf0@gmail.com::w6NV4TD7Y1v5x7AS:0000000000000000000000000000000000000005a9D X-Hashcash: 1:20:141105:linux-kernel@vger.kernel.org::MacOIKc5kD3pS0FV:0000000000000000000000000000000007qFT Date: Wed, 05 Nov 2014 23:01:48 +0100 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Tue, Nov 04 2014, Gregory Fong wrote: >> The alignment in cma_alloc() is done w.r.t. the bitmap. This is a >> problem when, for example: >> >> - a device requires 16M (order 12) alignment >> - the CMA region is not 16 M aligned On Wed, Nov 05 2014, Weijie Yang wrote: > I think the device driver should ensure that situation could not occur, > by assign suitable alignment parameter in cma_declare_contiguous(). What about default CMA area? Besides, I think principle of least surprise applies here and alignment should be physical. -- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michał “mina86” Nazarewicz (o o) ooo +------ooO--(_)--Ooo-- -- 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/