Member Avatar for nuliknol

Hi,
I am writing my own OS for 64bit processors and I am stuck with the problem of general protection. My OS will not rely on page fault to implement user space protection mechanism, so I found there is a way to do it with segment limit checking:

This presentation from VMWare

http://download3.vmware.com/vmworld/2005/pac346.pdf

on page 20 says:

> - Initial AMD64 architecture did not include segmentation in 64-bit mode
> - Segmentation also missing from EMT64T
>
> How do we protect the VMM ?
> - 64-bit guest support requires additional hardware assitance
> - Segment limit checks available in 64-bit mode on newer AMD processors

Now, I have the newer AMD processor model and my question is how do I achieve limit segment limit check on AMD processor in 64-bit (long) mode ? I have downloaded the Sep 2011 version (lastest) of developer's manual and I can't find how to do this in any place, please help.

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Member Avatar for nuliknol

found it:
Long Mode Segment Limit Enable bit (LMSLE bit 13)

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