Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755060AbXEUJys (ORCPT ); Mon, 21 May 2007 05:54:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754540AbXEUJyk (ORCPT ); Mon, 21 May 2007 05:54:40 -0400 Received: from embla.aitel.hist.no ([158.38.50.22]:51787 "HELO embla.aitel.hist.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754512AbXEUJyk (ORCPT ); Mon, 21 May 2007 05:54:40 -0400 Message-ID: <46516A14.2000102@aitel.hist.no> Date: Mon, 21 May 2007 11:44:52 +0200 From: Helge Hafting User-Agent: Icedove 1.5.0.10 (X11/20070329) MIME-Version: 1.0 To: Dave Airlie CC: Jon Smirl , Jesse Barnes , jonsmirl@gmail.com, linux-kernel@vger.kernel.org Subject: Re: [RFC] enhancing the kernel's graphics subsystem References: <200705171423.46748.jesse.barnes@intel.com> <21d7e9970705210127o2360cd63mb8a41fdab9f211f9@mail.gmail.com> <465161B0.9050800@aitel.hist.no> <21d7e9970705210227x27234e2dme4e731a53f977082@mail.gmail.com> In-Reply-To: <21d7e9970705210227x27234e2dme4e731a53f977082@mail.gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3486 Lines: 88 Dave Airlie wrote: > On 5/21/07, Helge Hafting wrote: >> Dave Airlie wrote: >> > On 5/21/07, Jon Smirl wrote: >> >> On Thu, 17 May 2007 14:23:45 -0700, Jesse Barnes wrote: >> >> >> >> > In collaboration with the FB guys, we've been working on >> enhancing the >> >> > kernel's graphics subsystem in an attempt to bring some sanity >> to the >> >> > Linux graphics world and avoid the situation we have now where >> several >> >> > kernel and userspace drivers compete for control of graphics >> devices. >> >> >> >> How is supporting different users logged into each head going to >> work? >> >> The original model for this was to give each head its own fbdev >> device. >> >> It is important that each user be able to set their own mode without >> >> being >> >> root. >> > >> > TThe problem with that is the concept of heads is flawed... there is >> > in reality no such >> > thing, you have crtcs and outputs, no heads. So any attempt to enforce >> > the head concept involves putting policy into the kernel, as if I have >> > 3 outputs but 2 crtcs how do I decide the mappings without the admin >> > telling the kernel, >> > >> Solution: >> One device per crtc. You can then have two users, running consoles >> or xservers on their crtcs, without having to involve root. > > Thats pretty much what the code does, but you still are putting a > certain amount of policy in the kernel... What policy would that be? The mapping is set by root from userspace, not by the kernel. The same for ownership to crtc devices. The kernel may have to provide some default so "init=/bin/sh" will work, that's all. >> >> The crtc->output mapping must still be done by root of course. >> >> This solution allow the useful case where the computer boots, the boot >> scripts >> set up a crtc->output mapping. Then users log in through the >> various consoles (using getty or xdm or similiar) using their grahphical >> devices in whatever way they want. A true multiseat setup. >> >> >> And if one user needs to use all the screens for multi-display work? >> Let root change the mappings, possibly through some sudo setup. >> > > Multiseat isn't what i would want as a default on any machine, so the Sure. Not multiseat by default, as the kernel can't know which output goes with which keyboard. All I want it a system that allows multiseat for those that care to set it up. > default setup should be to clone the single user onto as many screens > as possible, as this is what users expect.. the system startup scripts > can then reconfigure it, to suit the admins needs.. Sure. Well, when using multiple screens as a single user, then I don't want cloning. I want a multi-screen desktop. The laptop user with a video projector is about the one case I know where cloning is wanted. Unfortunately the kernel can't always know which outputs are in use, so I see how cloning may have to be the default. :-/ Helge Hafting > > Dave. >> > - > 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/ - 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/