From: Zachary Amsden <zach@vmware.com>
To: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Andi Kleen <ak@suse.de>, Andrew Morton <akpm@osdl.org>,
Linus Torvalds <torvalds@osdl.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [patch] i386: remove IOPL check on task switch
Date: Sat, 04 Nov 2006 11:19:53 -0800 [thread overview]
Message-ID: <454CE7D9.3070308@vmware.com> (raw)
In-Reply-To: <200611031900_MC3-1-D041-6F32@compuserve.com>
Chuck Ebbert wrote:
> In-Reply-To: <454B850C.3050402@vmware.com>
>
> 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
call.
Zach
next prev parent reply other threads:[~2006-11-04 19:19 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-03 23:57 [patch] i386: remove IOPL check on task switch Chuck Ebbert
2006-11-04 19:19 ` Zachary Amsden [this message]
2006-11-04 19:39 ` Zachary Amsden
2006-11-04 19:52 ` Linus Torvalds
2006-11-04 20:09 ` Zachary Amsden
2006-11-04 20:02 ` Andi Kleen
-- strict thread matches above, loose matches on Subject: below --
2006-11-04 0:00 Chuck Ebbert
2006-11-03 6:27 Chuck Ebbert
2006-11-03 18:06 ` Zachary Amsden
2006-11-03 18:41 ` Andi Kleen
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