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From: "Wang, Baojun" <wangbj@lzu.edu.cn>
To: linuxppc-embedded@ozlabs.org,
 "Bai Shuwei" <baishuwei@gmail.com>
Subject: Re: ring on PowerPC
Date: Wed, 31 Oct 2007 14:12:34 +0800
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On Wednesday 31 October 2007 13:05:16, Bai Shuwei wrote=EF=BC=9A
> Hi, everyone
>    As we know, the program on the X86 can run on the differnt ring(0, 1, =
2,
> 3) and the linux kernel run in the ring 0 and user program in the ring 3.
> And now I want to know wether there is a simple mechanism on the PowerPC
> architecture? thx all!
>
> best regards!
>
> Buroc

powerpc has a machine state register(MSR), bit MSR_PR present the current=20
privilege level, if msr & MSR_PR, then it's from user space, otherwise(msr =
&=20
MSR_PR =3D=3D 0) it's kernel space.

besides, the linux implementation only use ring0 and ring3 under i386, ring=
0=20
is highest(kernel space), ring3 is lowest (userspace)

Wang
=2D-=20
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