Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752714AbbEHIfW (ORCPT ); Fri, 8 May 2015 04:35:22 -0400 Received: from mail-wg0-f45.google.com ([74.125.82.45]:32990 "EHLO mail-wg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752226AbbEHIfR (ORCPT ); Fri, 8 May 2015 04:35:17 -0400 Date: Fri, 8 May 2015 10:37:35 +0200 From: Daniel Vetter To: One Thousand Gnomes Cc: Daniel Vetter , Thierry Reding , Benjamin Gaignard , "linux-media@vger.kernel.org" , Linux Kernel Mailing List , "dri-devel@lists.freedesktop.org" , Hans Verkuil , Laurent Pinchart , Rob Clark , Dave Airlie , Sumit Semwal , Tom Gall Subject: Re: [RFC] How implement Secure Data Path ? Message-ID: <20150508083735.GB15256@phenom.ffwll.local> Mail-Followup-To: One Thousand Gnomes , Thierry Reding , Benjamin Gaignard , "linux-media@vger.kernel.org" , Linux Kernel Mailing List , "dri-devel@lists.freedesktop.org" , Hans Verkuil , Laurent Pinchart , Rob Clark , Dave Airlie , Sumit Semwal , Tom Gall References: <20150505175405.2787db4b@lxorguk.ukuu.org.uk> <20150506083552.GF30184@phenom.ffwll.local> <20150506091919.GC16325@ulmo.nvidia.com> <20150506131532.GC30184@phenom.ffwll.local> <20150507132218.GA24541@ulmo.nvidia.com> <20150507135212.GD30184@phenom.ffwll.local> <20150507174003.2a5b42e6@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150507174003.2a5b42e6@lxorguk.ukuu.org.uk> X-Operating-System: Linux phenom 4.0.0-rc3+ User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2118 Lines: 46 On Thu, May 07, 2015 at 05:40:03PM +0100, One Thousand Gnomes wrote: > On Thu, 7 May 2015 15:52:12 +0200 > Daniel Vetter wrote: > > > On Thu, May 07, 2015 at 03:22:20PM +0200, Thierry Reding wrote: > > > On Wed, May 06, 2015 at 03:15:32PM +0200, Daniel Vetter wrote: > > > > Yes the idea would be a special-purpose allocater thing like ion. Might > > > > even want that to be a syscall to do it properly. > > > > > > Would you care to elaborate why a syscall would be more proper? Not that > > > I'm objecting to it, just for my education. > > > > It seems to be the theme with someone proposing a global /dev node for a > > few system wide ioctls, then reviewers ask to make a proper ioctl out of > > it. E.g. kdbus, but I have vague memory of this happening a lot. > > kdbus is not necessarily an advert for how to do anything 8) > > If it can be user allocated then it really ought to be one or more device > nodes IMHO, because you want the resource to be passable between users, > you need a handle to it and you want it to go away nicely on last close. > In the cases where the CPU is allowed to or expected to have write only > access you also might want an mmap of it. dma-buf user handles are fds, which means anything allocated can be passed around nicely already. The question really is whether we'll have one ioctl on top of a special dev node or a syscall. I thought that in these cases where the dev node is only ever used to allocate the real thing, a syscall is the preferred way to go. > I guess the same kind of logic as with GEM (except preferably without > the DoS security holes) applies as to why its useful to have handles to > the DMA buffers. We have handles (well file descriptors) to dma-bufs already, I'm a bit confused what you mean? -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch -- 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/