From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Smirl Subject: Re: [RFC] Video Mode Handling Date: Mon, 9 Aug 2004 07:56:49 -0700 (PDT) Sender: linux-fbdev-devel-admin@lists.sourceforge.net Message-ID: <20040809145649.7829.qmail@web14925.mail.yahoo.com> References: <200408091559.18436.adaplas@hotpop.com> Mime-Version: 1.0 Return-path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.12] helo=sc8-sf-mx2.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1BuBZx-0001Lb-Ap for linux-fbdev-devel@lists.sourceforge.net; Mon, 09 Aug 2004 07:56:49 -0700 Received: from web14925.mail.yahoo.com ([216.136.225.11]) by sc8-sf-mx2.sourceforge.net with smtp (Exim 4.34) id 1BuBZx-0007Ao-1C for linux-fbdev-devel@lists.sourceforge.net; Mon, 09 Aug 2004 07:56:49 -0700 In-Reply-To: <200408091559.18436.adaplas@hotpop.com> Errors-To: linux-fbdev-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: List-Post: List-Help: List-Subscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: adaplas@pol.net, Linux Fbdev development list Cc: Andrew Morton --- "Antonino A. Daplas" wrote: > I guess most people will agree that writing to the hardware belongs > in the kernel, while choosing the correct values to write belongs to > userspace. The unanswered question is the middle part, who does the > verification? At OLS we talk about a system like this: 1) user owns graphics devices 2) user sets mode with string (or similar) format using ioctl common to all drivers. 3) driver is locked to prevent multiple mode sets 4) common code takes this string and does a hotplug event with it. 5) hotplug event runs root context in user space 6) mode is decoded and verified, this may involve a little process that maintains the DDC database and reads a file of legal modes. Other schemes are possible. 7a) mode is set using VBIOS and vm86, signal driver mode is set 7b) the register values needed to set the mode are passed into a root priv ioctl. 8) driver is unlocked. In this model all of the verification happens in user space. If you want to set modes other than the ones from DDC you have to add them to the config file. There is no need for DDC support and mode verification in the kernel. To give credit this is Alan Cox's design. ===== Jon Smirl jonsmirl@yahoo.com __________________________________ Do you Yahoo!? New and Improved Yahoo! Mail - Send 10MB messages! http://promotions.yahoo.com/new_mail ------------------------------------------------------- This SF.Net email is sponsored by OSTG. Have you noticed the changes on Linux.com, ITManagersJournal and NewsForge in the past few weeks? Now, one more big change to announce. We are now OSTG- Open Source Technology Group. Come see the changes on the new OSTG site. www.ostg.com