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From: Alex Henrie <alexhenrie24@gmail.com>
Date: Tue, 12 May 2015 12:05:45 -0600
Message-ID: <CAMMLpeR-JZTTLGY6yovnHdz7esAvRMrMeSRpWAKyvgenREM24g@mail.gmail.com>
Subject: Re: [PATCH v2] x86: Preserve iopl on fork and execve
To: Austin S Hemmelgarn <ahferroin7@gmail.com>
Cc: Arjan van de Ven <arjanvandeven@gmail.com>, Ingo Molnar <mingo@kernel.org>,
        One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
        Kees Cook <keescook@chromium.org>, "H . Peter Anvin" <hpa@zytor.com>,
        Doug Johnson <dougvj@gmail.com>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Tyler Hicks <tyhicks@canonical.com>,
        Al Viro <viro@zeniv.linux.org.uk>, LKML <linux-kernel@vger.kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Borislav Petkov <bp@alien8.de>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Arjan van de Ven <arjan@infradead.org>,
        Denys Vlasenko <dvlasenk@redhat.com>, Brian Gerst <brgerst@gmail.com>
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2015-05-12 9:47 GMT-06:00 Austin S Hemmelgarn <ahferroin7@gmail.com>:
> On 2015-05-12 11:25, Arjan van de Ven wrote:
>> If you look at a modern linux distro, nothing should need/use iopl and
>> co anymore, so maybe an interesting
>> question is if we can stick these behind a CONFIG_ option (default on
>> of course for compatibility)... just like
>> some of the /dev/mem like things are now hidable for folks who know
>> they don't need them.
>
> Personally, I _really_ like this idea.  The only thing I know of on any
> modern distro that even considers using ioperm is hwclock, and it only does
> so if it can't access the RTC through other means (and if you have an RTC,
> you really should have the /dev interface enabled).

Removing iopl might be OK. Removing ioperm would break my use case of
legacy code that needs direct access to the parallel port.

-Alex
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