linux-kernel - Setting of PE bit reboots the system

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Date:	Sun, 31 Jan 2010 00:06:12 +0530
From:	Swapnil Pimpale <swapnil.pict@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: Setting of PE bit reboots the system

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.
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