From: Andi Kleen <ak@suse.de>
To: Zachary Amsden <zach@vmware.com>
Subject: Re: [patch] i386: remove IOPL check on task switch
Date: Sat, 4 Nov 2006 21:02:12 +0100
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Cc: Chuck Ebbert <76306.1226@compuserve.com>, Andrew Morton <akpm@osdl.org>,
       Linus Torvalds <torvalds@osdl.org>,
       linux-kernel <linux-kernel@vger.kernel.org>
References: <200611031900_MC3-1-D041-6F32@compuserve.com> <454CE7D9.3070308@vmware.com> <454CEC5C.2050507@vmware.com>
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> Ok, checking shows Linus put it back to stop NT leakage. 

It is also needed to stop AC leakage

> This is  
> correct, but unlikely.  Would be nice to avoid it unless absolutely 
> necessary.  Perhaps xor eflags old and new and only set_system_eflags() 
> if non-ALU bits have changed.

If it's worth it...

If it's worth for the context switch i think it would make 
more sense to do it for the normal restore_flags() etc. which are much
more common (and could be actually handled in most cases with test + jump + sti)

-Andi
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