From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1JFLN6-0004Xk-Hn for qemu-devel@nongnu.org; Wed, 16 Jan 2008 22:24:52 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1JFLN3-0004V6-26 for qemu-devel@nongnu.org; Wed, 16 Jan 2008 22:24:52 -0500 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1JFLN2-0004V3-Pm for qemu-devel@nongnu.org; Wed, 16 Jan 2008 22:24:48 -0500 Received: from terminus.zytor.com ([198.137.202.10]) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1JFLN2-0006K2-F8 for qemu-devel@nongnu.org; Wed, 16 Jan 2008 22:24:48 -0500 Message-ID: <478EC91C.1030601@zytor.com> Date: Wed, 16 Jan 2008 22:18:52 -0500 From: "H. Peter Anvin" MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Motivation of BIOS patch? 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 I saw the following patch in the Qemu source: Index: rombios.c =================================================================== RCS file: /cvsroot/bochs/bochs/bios/rombios.c,v retrieving revision 1.174 diff -u -w -r1.174 rombios.c --- rombios.c 17 Oct 2006 16:48:05 -0000 1.174 +++ rombios.c 8 Feb 2007 21:57:48 -0000 @@ -9472,6 +9472,14 @@ mov eax, #0x00040000 call eax + ;; reset the memory (some boot loaders such as syslinux suppose + ;; that the memory is set to zero) + mov edi, #0x00040000 + mov ecx, #0x40000 / 4 + xor eax, eax + rep + stosd + ;; return to 16 bit protected mode first db 0xea dd rombios32_10 Being the SYSLINUX author I'm more than a little surprised about this; this is probably indicative of a serious bug (possibly now fixed). Anyone who has any information about this? -hpa