From owner-freebsd-hackers@FreeBSD.ORG Fri Oct 21 18:24:06 2005 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id B93FE16A422 for ; Fri, 21 Oct 2005 18:24:06 +0000 (GMT) (envelope-from gbergling@0xfce3.net) Received: from einhorn.in-berlin.de (einhorn.in-berlin.de [192.109.42.8]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9936E43D46 for ; Fri, 21 Oct 2005 18:24:04 +0000 (GMT) (envelope-from gbergling@0xfce3.net) X-Envelope-From: gbergling@0xfce3.net X-Envelope-To: Received: from node26.0xfce3.net (port-212-202-34-7.dynamic.qsc.de [212.202.34.7]) (authenticated bits=128) by einhorn.in-berlin.de (8.12.10/8.12.10/Debian-4) with ESMTP id j9LIO0Xl014919 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Fri, 21 Oct 2005 20:24:00 +0200 Received: from node26.0xfce3.net (localhost [127.0.0.1]) by node26.0xfce3.net (8.13.4/8.13.4) with ESMTP id j9LINxZ7011096 for ; Fri, 21 Oct 2005 20:23:59 +0200 (CEST) (envelope-from gbergling@0xfce3.net) Received: (from gordon@localhost) by node26.0xfce3.net (8.13.4/8.13.4/Submit) id j9LINw9m011095 for freebsd-hackers@freebsd.org; Fri, 21 Oct 2005 20:23:58 +0200 (CEST) (envelope-from gbergling@0xfce3.net) X-Authentication-Warning: node26.0xfce3.net: gordon set sender to gbergling@0xfce3.net using -f Date: Fri, 21 Oct 2005 20:23:58 +0200 From: Gordon Bergling To: freebsd-hackers@freebsd.org Message-ID: <20051021182358.GA11009@node26.0xfce3.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Url: X-Operating-System: FreeBSD 6.0-RC1 i386 X-Host-Uptime: 8:12PM up 1:37, 3 users, load averages: 0.23, 0.13, 0.05 User-Agent: Mutt/1.5.11 X-Spam-Score: (0.721) AWL,BAYES_40,FORGED_RCVD_HELO,HELO_DYNAMIC_DHCP X-Scanned-By: MIMEDefang_at_IN-Berlin_e.V. on 192.109.42.8 Subject: locking of a subsystem (remove of spl calls) X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 21 Oct 2005 18:24:06 -0000 Hi, I am about to write a special display driver, which should be something like a framebuffer device, in terms of FreeBSD. I whould like to make this driver from at the beginning MPSAFE, but I am not sure that this is possible. Looking at some devices in sys/dev/fb and sys/dev/syscons there are a lot of spl calls with make these drivers require GIANT. My question is now where to start. Should I write my driver with spl calls or is there an MPSAFE way which could I take? And while I am here how hard whould it to get the looking of syscons right. I have studied the source code for a while now and could take this part. I am not sure about the other kernel subsystems like tty for example. Whould it be possible to lock down syscons and maybe some device in sys/dev/fb without a complete GIANT removal from the tty subsystem? best regards, Gordon -- Gordon Bergling http://www.0xFCE3.net/ PGP Fingerprint: 7732 9BB1 5013 AE8B E42C 28E0 93B9 D32B C76F 02A0 RIPE-HDL: MDTP-RIPE "There is no place like 127.0.0.0/8"