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Date: Sat, 12 Apr 2008 12:49:47 -0700
From: Arjan van de Ven <arjan@infradead.org>
To: Erik Bosman <ebn310@few.vu.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
       "H. Peter Anvin" <hpa@zytor.com>,
       Andrea Arcangeli <andrea@cpushare.com>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] x86: Implement prctl PR_GET_TSC and PR_SET_TSC
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On Fri, 11 Apr 2008 18:55:58 +0200 (CEST)
Erik Bosman <ebn310@few.vu.nl> wrote:

> 
>     x86: Implement prctl PR_GET_TSC and PR_SET_TSC
> 
>     This patch adds a configure option CONFIG_DISABLE_TSC
>     (off by default) for the x86 platform to enable the
>     PR_GET_TSC and PR_SET_TSC commands. These control the
>     ability to use the timestamp counter from userspace
>     (the RDTSC instruction.)
> 
>     This patch uses code earlier used to disable the
>     timestamp counter for the SECCOMP framework. It used
>     to disable the RDTSC on 32 bit kernels, but allow it
>     on x86_64. This patch makes SECCOMP disable the
>     timestamp counter whenever CONFIG_DISABLE_TSC is
>     enabled.


Hi,

why did you make this a configuration option? In general it's not
a good idea to make userspace visible ABI's (PR_* clearly is one of these)
a CONFIG option unless there's some HUGE space saving going on.
I don't see that here....

So can you explain your rationale for making this a config option?

Greetings,
   Arjan van de Ven 

-- 
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