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Date:	Sat, 04 Nov 2006 11:19:53 -0800
From:	Zachary Amsden <>
To:	Chuck Ebbert <>
Cc:	Andi Kleen <>, Andrew Morton <>,
	Linus Torvalds <>,
	linux-kernel <>
Subject: Re: [patch] i386: remove IOPL check on task switch

Chuck Ebbert wrote:
> In-Reply-To: <>
> On Fri, 03 Nov 2006 10:06:04 -0800, Zachary Amsden wrote:
>> Chuck Ebbert wrote:
>>> IOPL is implicitly saved and restored on task switch,
>>> so explicit check is no longer needed.
>> Nack.  This is used for paravirt-ops kernels that use IOPL'd userspace.  
> How does that work?  In the stock kernel, anything done by
> the call to set_iopl_mask() (that was removed by the patch)
> will be nullified by the 'popfl' at the end of the switch_to()
> macro.

Who put a popfl back in switch_to?  I took it out some time ago.  It 
should not be there.  The only reason for it was to stop IOPL leaking 
from one process to another from a sleep during a sysenter based system 

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