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Date: Wed, 20 Jul 2011 21:42:40 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Mike Waychison <mikew@google.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@suse.de>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] x86: Allow disabling of sys_iopl, sys_ioperm
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* Mike Waychison <mikew@google.com> wrote:

> On Thu, Jul 14, 2011 at 3:35 PM, H. Peter Anvin <hpa@zytor.com> wrote:
> > On 07/14/2011 03:31 PM, Andrew Morton wrote:
> >>
> >> sys_iopl() is missing asmlinkage.
> >>
> >> It would be far more conventional to use cond_syscall().  Perhaps by
> >> adding a CONFIG_X86 area into kernel/sys_ni.c
> >>
> >> fyi, I'm offering special deals on checkpatch.pl site licenses this month.
> >
> > Again, I don't think this makes sense as a compile-time-only option.
> 
> echo "enabled" > /proc/sys/kernel/iopl_available
> echo "disabled" > /proc/sys/kernel/iopl_available
> echo "locked" > /proc/sys/kernel/iopl_available

1, 0 and -1 ought to be a rather straightforward mapping to 'on', 
'off' and 'off forever'.

Thanks,

	Ingo