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From: Daniel Phillips <phillips@arcor.de>
To: Luca Barbieri <ldb@ldb.ods.org>,
       Linux-Kernel ML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH][RFC] x86 multiple user-mode privilege rings
Date: Mon, 28 Oct 2002 13:12:02 +0100
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Cc: Karim Yaghmour <karim@opersys.com>
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On Sunday 27 October 2002 03:48, Luca Barbieri wrote:
> Short explaination: 
> This patch implements a feature called "x86 multiring", which is a
> shorthand for x86 multiple user-mode privilege rings support. 
> It allows user-mode programs to create DPL 1 and 2 segments and get a
> modifiable per-process copy of IDT. 
> 
> User Mode Linux can use these features to implement a syscall mechanism
> identical to the one used by the kernel-mode kernel, and thus much
> faster than the current one, with free memory protection and with zero
> context switches. 
> 
> Wine could also use it to achieve fast syscall-level emulation of
> Windows NT (and, to a lesser extent, Windows 3.1 and 9x). 

Karim once talked about doing a flavor of Adeos that would drop a running 
kernel into ring 1 as a result of insmodding an Adeos module, which would 
allow Adeos to combine an unmodified Linux kernel with a realtime executive.

-- 
Daniel
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