Re: [PATCH v2] x86: Preserve iopl on fork and execve

From: Austin S Hemmelgarn
Date: Tue May 12 2015 - 11:47:55 EST

On 2015-05-12 11:25, Arjan van de Ven wrote:

also the interesting question is:
can a process give up these perms?
otherwise it becomes a "once given, never gotten rid of" hell hole.

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).

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