From mboxrd@z Thu Jan 1 00:00:00 1970 From: Antonino Daplas Subject: Re: Some questions Date: 12 Mar 2003 04:07:53 +0800 Sender: linux-fbdev-devel-admin@lists.sourceforge.net Message-ID: <1047407816.1013.182.camel@localhost.localdomain> References: Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Received: from pine.compass.com.ph ([202.70.96.37]) by sc8-sf-list1.sourceforge.net with smtp (Exim 3.31-VA-mm2 #1 (Debian)) id 18sq5T-0005E4-00 for ; Tue, 11 Mar 2003 12:10:59 -0800 In-Reply-To: Errors-To: linux-fbdev-devel-admin@lists.sourceforge.net List-Help: List-Post: List-Subscribe: , List-Id: List-Unsubscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" To: James Simmons Cc: Geert Uytterhoeven , Thomas Winischhofer , Linux Fbdev development list On Wed, 2003-03-12 at 00:29, James Simmons wrote: > > > So, I think fbcon should also detect if the previous console is not > > fbcon (ie previous con > last_fbvc || previous con < first_fbvc), and if > > it isn't, force an fb_set_par. > > This whole idea of mapping a specific VC to a specific piece of hardware > is just plain dumb and overly complex. The new console system will > allocate a set of 16 console to each independent VT. > Well, you have info->currcon, fg_console etc... No mapping is done, fbcon will just keep track of the tty's it's currently switched to (vt.c does it, and so does fbcon_switch), and fbcon will just look if the vc has a valid PID (which means a process installed its own vc) and therefore not trust it to completely preserve the graphics state. Note that X does something like this to protect itself. When switch from console to X, it refreshes its own registers. I think you may need some support for this. Several have already reported that switching from X to a console results in a corrupted display which can be cleared by doing an fbset. The choices are: 1. refresh the registers at every switch - slowest but guarantees hardware state is always preserved 2. do not refresh unless var changed - fasted but can result in corruption/crash if registers were changed behind the back of fbdev 3. selective refresh - do not refresh if switching between "trusted" consoles, refresh if switching from "untrusted" consoles. 4. Find a method to detect if the registers were changed behind the back of fbdev. Tony ------------------------------------------------------- This SF.net email is sponsored by:Crypto Challenge is now open! Get cracking and register here for some mind boggling fun and the chance of winning an Apple iPod: http://ads.sourceforge.net/cgi-bin/redirect.pl?thaw0031en