From patchwork Mon Mar 23 21:55:01 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Glauber Costa X-Patchwork-Id: 13846 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n2NLwmWC006819 for ; Mon, 23 Mar 2009 21:58:49 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757109AbZCWV6q (ORCPT ); Mon, 23 Mar 2009 17:58:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757127AbZCWV6q (ORCPT ); Mon, 23 Mar 2009 17:58:46 -0400 Received: from mx2.redhat.com ([66.187.237.31]:38097 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756458AbZCWV6p (ORCPT ); Mon, 23 Mar 2009 17:58:45 -0400 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id n2NLwdCD031735; Mon, 23 Mar 2009 17:58:39 -0400 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx2.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n2NLwY38008213; Mon, 23 Mar 2009 17:58:34 -0400 Received: from localhost.localdomain (vpn-10-93.bos.redhat.com [10.16.10.93]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id n2NLwbXQ012117; Mon, 23 Mar 2009 17:58:38 -0400 From: Glauber Costa To: qemu-devel@nongnu.org Cc: kvm@vger.kernel.org, bochs-developers@lists.sourceforge.net Subject: [PATCH] compute checksum for roms bigger than a segment Date: Mon, 23 Mar 2009 18:55:01 -0300 Message-Id: <1237845301-15796-1-git-send-email-glommer@redhat.com> X-Scanned-By: MIMEDefang 2.58 on 172.16.27.26 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Some option roms (e1000 provided by gpxe project as an example) are bigger than a segment. The current algorithm to compute the checksum fails in such case. To proper compute the checksum, this patch deals with the possibility of the rom's size crossing a segment border. We don't need to worry about it crossing more than one segment border, since the option roms format only save one byte to store the image size (thus, maximum size = 0xff = 128k = 2 segments) Signed-off-by: Glauber Costa --- bios/rombios.c | 33 +++++++++++++++++++++++++++------ 1 files changed, 27 insertions(+), 6 deletions(-) diff --git a/bios/rombios.c b/bios/rombios.c index bc43251..6fede17 100644 --- a/bios/rombios.c +++ b/bios/rombios.c @@ -10162,22 +10162,43 @@ no_serial: ret rom_checksum: - push ax - push bx - push cx + pusha + push ds + xor ax, ax xor bx, bx xor cx, cx + xor dx, dx + mov ch, [2] shl cx, #1 + + jnc checksum_loop + mov dx, cx + mov cx, #0xffff + checksum_loop: add al, [bx] inc bx loop checksum_loop + + cmp dx, #0 + je checksum_out + + add al, [bx] + mov cx, dx + mov dx, ds + add dx, #0x1000 + mov ds, dx + xor dx, dx + xor bx, bx + + jmp checksum_loop + +checksum_out: and al, #0xff - pop cx - pop bx - pop ax + pop ds + popa ret