From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753543Ab2ARMOV (ORCPT ); Wed, 18 Jan 2012 07:14:21 -0500 Received: from moutng.kundenserver.de ([212.227.126.171]:53218 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751915Ab2ARMOU (ORCPT ); Wed, 18 Jan 2012 07:14:20 -0500 From: Arnd Bergmann To: "Semwal, Sumit" Subject: Re: [PATCH] dma-buf: Use EXPORT_SYMBOL Date: Wed, 18 Jan 2012 12:14:11 +0000 User-Agent: KMail/1.12.2 (Linux/3.2.0-rc7; KDE/4.3.2; x86_64; ; ) Cc: Robert Morell , Mauro Carvalho Chehab , Konrad Rzeszutek Wilk , linux-kernel@vger.kernel.org, sumit.semwal@linaro.org, airlied@linux.ie, dri-devel@lists.freedesktop.org References: <1326845297-6233-2-git-send-email-rmorell@nvidia.com> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201201181214.12055.arnd@arndb.de> X-Provags-ID: V02:K0:yDp0vA3YeQMqH3oStXuVDeKb1zK31WVsZ6oD6Yw3UuB aioa+KuFuB3sgMsKwAft6Tr/lpSVRmlO6oT+oD77QUTpYSOHQR AEIPpYc9sxaz/5bsZ1riDzIOufn024VekMWy0enpGLxukKFCZm 3LDJfaY0Ew935U4H+wJDPYN60lVoONydrzagr3THaWngc2gNVn XAUIR4uO1n043UxIuUd74txy2CBu2eOze/lVhk8zuHaH9/IrIh 0UbRcKHXqQCH+YN2Dzv4ExWlfab8v37I1fbPrhDhBdVIZ1Ke5/ Dpgff1UcneIHmlgn2z2d5aU/YWEkVX1A/rQohiclfyMaqa5/4+ fx3dpgWG+DGVrA8AUsws= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 18 January 2012, Semwal, Sumit wrote: > On Wed, Jan 18, 2012 at 5:38 AM, Robert Morell wrote: > > EXPORT_SYMBOL_GPL is intended to be used for "an internal implementation > > issue, and not really an interface". The dma-buf infrastructure is > > explicitly intended as an interface between modules/drivers, so it > > should use EXPORT_SYMBOL instead. > > + Konrad, Arnd, Mauro: there were strong objections on using > EXPORT_SYMBOL in place of EXPORT_SYMBOL_GPL by all 3 of them; I > suggest we first arrive at a consensus before merging this patch. We discussed this before. The reason for using EXPORT_SYMBOL_GPL here is that the interface is low-level and that it's meant to be used by subsystems that export user-level interface based on that and come with their own device driver interface, such as V4L or DRM. While there is an eternal debate over whether there should or should not be out of tree device drivers, I think there is very little to gain by allowing dma_buf to be used by out of tree *subsystems*. Further, a device driver that tries to use the interface but sits outside of the regular subsystems is a bad technical choice and we should not encourage those either. NAK Arnd