Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751642AbbEGQkc (ORCPT ); Thu, 7 May 2015 12:40:32 -0400 Received: from 251.110.2.81.in-addr.arpa ([81.2.110.251]:44698 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750905AbbEGQka (ORCPT ); Thu, 7 May 2015 12:40:30 -0400 Date: Thu, 7 May 2015 17:40:03 +0100 From: One Thousand Gnomes To: Daniel Vetter Cc: 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: <20150507174003.2a5b42e6@lxorguk.ukuu.org.uk> In-Reply-To: <20150507135212.GD30184@phenom.ffwll.local> 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> Organization: Intel Corporation X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.27; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1498 Lines: 33 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. 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. Alan -- 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/