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

From: Austin S Hemmelgarn
Date: Tue May 12 2015 - 14:12:29 EST

On 2015-05-12 14:05, Alex Henrie wrote:
2015-05-12 9:47 GMT-06:00 Austin S Hemmelgarn <ahferroin7@xxxxxxxxx>:
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.


The discussion isn't about outright removing them, just providing a config option to disable them. It might be a good idea though to provide separate config options for each of iopl() and ioperm(), as iopl() is more dangerous, and ioperm() is more widely used, and people may need one but not want to have the other.

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