From mboxrd@z Thu Jan 1 00:00:00 1970 From: Antonino Daplas Subject: Re: Reading the EDID block for x86 machines Date: 13 Mar 2003 06:38:33 +0800 Sender: linux-fbdev-devel-admin@lists.sourceforge.net Message-ID: <1047508652.1005.6.camel@localhost.localdomain> References: <20030312181658.96700.qmail@web14912.mail.yahoo.com> 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 18tEua-0006iJ-00 for ; Wed, 12 Mar 2003 14:41:24 -0800 In-Reply-To: <20030312181658.96700.qmail@web14912.mail.yahoo.com> 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: Jon Smirl Cc: James Simmons , Linux Fbdev development list On Thu, 2003-03-13 at 02:16, Jon Smirl wrote: > --- Antonino Daplas wrote: > > Unless I missed some imported BIOS calls or other > > methods to do this or > > something similar in real-mode... > > You missed something. The address of the VBIOS ROM can > be controlled by writing to the PCI config space. You > can make the ROM appear anywhere you want it to. > > This happens even for the boot video device. > Somewhere very early in the boot the system BIOS > enabled the VBIOS ROM and copied it to C000. This is > the "shadow BIOS" option. > So the steps needed would be: 1. scan for pci devices looking for the vga controller type 2. if 1 is found other than the primary, disable the current controller 3. write to PCI config space of secondary controller the address you want it to appear (ie C000:0000). Can I use other addresses? 4. enable the controller 5. far call c000:0003 6. disable the controller 7. repeat Besides the finer points, did I miss anything obvious? 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