Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754456AbZGTXqY (ORCPT ); Mon, 20 Jul 2009 19:46:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754328AbZGTXqV (ORCPT ); Mon, 20 Jul 2009 19:46:21 -0400 Received: from solo.fdn.fr ([80.67.169.19]:34688 "EHLO solo.fdn.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754273AbZGTXqV (ORCPT ); Mon, 20 Jul 2009 19:46:21 -0400 Date: Tue, 21 Jul 2009 01:46:18 +0200 From: Samuel Thibault To: linux-kernel@vger.kernel.org, linux-console@vger.kernel.org Subject: inotify on /dev/vcsa? Message-ID: <20090720234618.GR5397@const.famille.thibault.fr> Mail-Followup-To: Samuel Thibault , linux-kernel@vger.kernel.org, linux-console@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.12-2006-07-14 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1209 Lines: 24 Hello, Powersaving is everywhere, including accessibility. User-level daemons use /dev/vcsa to know what text is displayed on the screen. Problem is: there is no way to _wait_ for an update to happen, so these daemons actually poll every e.g. 40ms so as to be reactive enough for smooth user experience. That means waking up 25 times per second, which is not so greenish while the computer could be completely idle else. An ioctl could be devised to wait for updates, but I was wondering if there could be a way to just use inotify for that. However, drivers/char/vc_screen.c would have to collect the list of opened files in order to notify all of them (processes may even have opened another node with same devno as /dev/vcsa), which is not really pretty, and actually maybe some other device drivers would want to achieve the same kind of thing, so I was wondering whether that could fit into another place like the generic device infrastructure? Samuel -- 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/