Message-ID: <52E5BC9C.9070400@intel.com>
Date: Mon, 27 Jan 2014 09:55:40 +0800
From: Ren Qiaowei <qiaowei.ren@intel.com>
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To: "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>
CC: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        x86@kernel.org, linux-kernel@vger.kernel.org,
        Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH v3 3/4] x86, mpx: add prctl commands PR_MPX_INIT, PR_MPX_RELEASE
References: <1390727338-20487-1-git-send-email-qiaowei.ren@intel.com> <1390727338-20487-4-git-send-email-qiaowei.ren@intel.com> <20140126082201.GB28831@gmail.com> <52E4C5F2.8070707@intel.com> <20140126083942.GB29339@gmail.com> <52E5BB66.8060104@zytor.com>
In-Reply-To: <52E5BB66.8060104@zytor.com>
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On 01/27/2014 09:50 AM, H. Peter Anvin wrote:
> On 01/26/2014 12:39 AM, Ingo Molnar wrote:
>>>
>>> It will be only once per startup.
>>
>> In that case it would be more efficient to make this part of the
>> binary execution environment so that exec() sets it up automatically,
>> not a separate prctl() syscall.
>>
>
> This is not necessarily possible, and in particular it might need to be
> deferred until the MPX runtime has initialized.
>
> What isn't clear to me is if these syscalls are needed at all, or if it
> would be better to just let the MPX runtile set BNDSTATUS and BNDCFGU
> directly in userspace.  The kernel cannot rely on them staying
> consistent across userspace anyway.
>
> Now, it might be beneficial for the kernel to have them anyway.  It's a
> bit of a tough call.
>
> 	-hpa
>
Peter, you mean we should remove these two call and do what they do in 
user-space, right?

Thanks,
Qiaowei
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