Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758092AbXFBI5m (ORCPT ); Sat, 2 Jun 2007 04:57:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753908AbXFBI5g (ORCPT ); Sat, 2 Jun 2007 04:57:36 -0400 Received: from smtp6-g19.free.fr ([212.27.42.36]:52006 "EHLO smtp6-g19.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753544AbXFBI5f (ORCPT ); Sat, 2 Jun 2007 04:57:35 -0400 Message-ID: <466131CB.20301@free.fr> Date: Sat, 02 Jun 2007 11:00:59 +0200 From: Thierry Merle User-Agent: Thunderbird 2.0.0.0 (X11/20070326) MIME-Version: 1.0 To: Mauro Carvalho Chehab CC: video4linux-list@redhat.com, linux-kernel@vger.kernel.org, Andrew Morton , Jiri Slaby Subject: Re: [PATCH 1/1] V4L: stk11xx, add a new webcam driver References: <2172422218943432279@wsc.cz> <1180364420.21547.160.camel@localhost> <1180378677.21547.189.camel@localhost> <1180383071.21547.230.camel@localhost> <465B49EB.4080204@free.fr> <465BBAFB.30906@free.fr> <1180448712.21547.314.camel@localhost> <465C7920.2080203@free.fr> <1180467116.9509.73.camel@localhost> <465F3361.106@free.fr> <1180739401.3904.50.camel@localhost> In-Reply-To: <1180739401.3904.50.camel@localhost> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1343 Lines: 33 Mauro Carvalho Chehab a ?crit : >>> This seems to be an interesting approach. >>> >>> >>> >> Interesting but impossible to do for ioctl calls. >> When the application does a ioctl(fd_of_mnt_video0,VIDIOC_G_FMT,&arg) >> for example, there is no way for the userspace helper to catch this ioctl. >> The application could only open/read from the userspace helper's file >> /mnt/video0. >> ioctl would still have to be done on the kernel device driver. >> I thought also about a /proc interface for decompression algorithms (a >> helper would listen on a /proc file and write on another /proc file) but >> /proc is not designed for that kind of thing. >> A separate library seems to be the simplest solution. >> > > There are some ways for this to work. For example, you may create a > helper device for the daemon driver to bind, even requiring it to have > root permission. > > Right, but I am afraid that complex userspace/kernelspace context changes breaks performance. Nevertheless, I will start to specify the framework. The helper daemon would link to the v4l2-apps/lib. - 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/