From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: fbdv/fbcon pending problems Date: Mon, 23 Feb 2004 11:53:14 +1100 Sender: linux-fbdev-devel-admin@lists.sourceforge.net Message-ID: <1077497593.5960.28.camel@gaston> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.11] helo=sc8-sf-mx1.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1Av4Za-0004mp-7M for linux-fbdev-devel@lists.sourceforge.net; Sun, 22 Feb 2004 17:07:50 -0800 Received: from gate.crashing.org ([63.228.1.57] ident=root) by sc8-sf-mx1.sourceforge.net with esmtp (TLSv1:AES256-SHA:256) (Exim 4.30) id 1Av4SG-0001AS-7d for linux-fbdev-devel@lists.sourceforge.net; Sun, 22 Feb 2004 17:00:16 -0800 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" To: James Simmons Cc: Linux Fbdev development list , Linux Kernel list Hi ! Here's a list of pending issues with fbdev (either upstream or in the fbdev bk treee), I figured posting it here may help getting more people on those issues as my time is sparse and I suppose James too. - First one, I will deal with, just writing it for completeness: When switching from KD_GRAPHICS to KD_TEXT (either same console changing mode or switching to a different console), we need a callback so the fbdev has a chance to restore the accel engine setting (or even the whole mode, to be safe). - Memory corruption problems. There is still at least one identified when using stty. Just use crazy values, like flipping rows & cols (like stty rows 132 cols 30) and usually, you'll see the box blow up very soon with heavy memory corruption. - mach64 lockups on LT-G (I'll try on an LT-Pro soon) plus other mach64 bugs in the new version in the bk fbdev, I'll have a patch for some of the problems, but I didn't find a good explanation for the accel lockups yet - Logo problems. When booting with a logo, then going to getty, the logo doesn't get erased until we actually switch to another console (or reset the console). At this point, using things like vi & scrolling up doesn't work properly. Actually, last time I tried, I had to switch back & forth twice before my console that had the logo got fully working with vi. - Back buffer problem: maybe related to the logo ? After boot, doing shift-pageup to go back to the boot message, usually you get crap displayed at various places. - On x86, various junk displayed when the fbdev takes over. Reported by radeonfb users, I couldn't test myself, I don't have an x86 with radeon at hand for the moment. Apparently, the takeover from vgacon doesn't properly "convert" the previous VGA text buffer content - stty & mode picking. Currently, fbcon_resize() (called when stty is used to resize the console) will hack a "var" strcture by just putting new width/height in it and pass that to set_var. The way the various drivers react to that mostly broken "var" structure is rather random. We need to explicitely differenciate between a mode that is "complete" (like what fbset or X passes down the fbdev) or a mode that is just width/height and eventually a hint of frequency, like what fbcon passes in this case. I added FB_ACTIVATE_FIND for that purpose, but that needs better driver support to "pick" up a proper mode. The algorithm for that isn't trivial. Could be moved to common code. - fbset doesn't resize the console. I consider that a regression from 2.4. I have some code based on the notification mecanism to address that, but it tends to trigger the same memory corruption problem as reported with stty & bogus coordinates. There is something hairy going on with console resizes. That code is a bit foreign to me though. Ok, that's all that comes to my mind right now, help is welcome :) Ben. ------------------------------------------------------- SF.Net is sponsored by: Speed Start Your Linux Apps Now. Build and deploy apps & Web services for Linux with a free DVD software kit from IBM. Click Now! http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click