From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754037Ab0A3SgO (ORCPT ); Sat, 30 Jan 2010 13:36:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753543Ab0A3SgO (ORCPT ); Sat, 30 Jan 2010 13:36:14 -0500 Received: from mail-pz0-f172.google.com ([209.85.222.172]:51193 "EHLO mail-pz0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752311Ab0A3SgN (ORCPT ); Sat, 30 Jan 2010 13:36:13 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type; b=cgzSNVDx/rugbO2eHhA9EhNGyd6JyOp1eaKyWgMKMo/ErKaSafQNq035e8lKLn6ntU 0hVkhgXYMxCfV0XQ1rHmmA6n0mpuRFqUKdrMG9OzzpF9ZQIA+0fXtwF85d3KMPVtGaaC nznrlOk1NxiKFmM28A2V0+dE388ORpyvY2Zqg= MIME-Version: 1.0 Date: Sun, 31 Jan 2010 00:06:12 +0530 Message-ID: Subject: Setting of PE bit reboots the system From: Swapnil Pimpale To: linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi all, I am working on Intel Core 2 Duo architecture. As a part of my academic project, I need to bring up the second core from the bootloader (GRUB). When the second core comes up, I need to switch it from real mode to protected mode. For this, I am trying to set the PE bit of cr0 register. But, whenever I set the PE bit the system reboots. For switching from real to protected mode I use the following steps: 1) Clear Interrupts 2) Load GDT 3) Set PE bit of cr0 4) Long Jump to Protected mode code Is there any thing that I am missing? Should the gate A20 line be turned on from the second core also? Is there any solution on the problem of setting PE bit? Thanks, Swapnil Pimpale.