From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.33) id 1BXT9O-00015t-Jw for qemu-devel@nongnu.org; Mon, 07 Jun 2004 19:03:30 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.33) id 1BXT9K-00015d-O3 for qemu-devel@nongnu.org; Mon, 07 Jun 2004 19:03:29 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.33) id 1BXT9K-00015a-6y for qemu-devel@nongnu.org; Mon, 07 Jun 2004 19:03:26 -0400 Received: from [81.209.184.159] (helo=dd2718.kasserver.com) by monty-python.gnu.org with esmtp (Exim 4.34) id 1BXT8g-0006nF-Mb for qemu-devel@nongnu.org; Mon, 07 Jun 2004 19:02:47 -0400 Received: from [192.168.0.7] (dsl-082-082-145-050.arcor-ip.net [82.82.145.50]) by dd2718.kasserver.com (Postfix) with ESMTP id 3E30BB76D2 for ; Tue, 8 Jun 2004 01:00:49 +0200 (CEST) Message-ID: <40C4F3ED.7050205@fabianowski.de> Date: Tue, 08 Jun 2004 01:02:05 +0200 From: Bartosz Fabianowski MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Purpose of Cirrus VGA BIOS Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Hi all I am trying to figure out how the new Cirrus emulation works. One thing I am still not sure about is the purpose of the Cirrus BIOS. The emulation coded inside QEMU seems to be trapping the graphics card interrupt as well as port and memory accesses. It also performs lots of operations and reacts to registers being changed or the interrupt being invoked. So, what exactly is the purpose of the graphics card BIOS in this scenario? What purpose does it serve? Obviously, a real Cirrus BIOS contains lots of code that would control a real Cirrus graphics card and that is totally unnecessary in QEMU. What other stuff does it contain that can't be done in native C code? - Bartosz