Re: [patch 5/9] x86/ioport: Reduce ioperm impact for sane usage further

[Willy Tarreau]

On Thu, Nov 07, 2019 at 11:00:27AM +0100, Thomas Gleixner wrote:
> Changing ioperm(single port, port range) to be ioperm(all) is going to
> break a bunch of test cases which actually check whether the permission is
> restricted to a single I/O port or the requested port range.

But out of curiosity, are these solely test cases or things that real
applications do ? We could imagine having a sysctl entry to indicate
whether or not we want strict compatibility with older code in which
case we'd take the slow path, or a modernized behavior using only the
fast path. If we managed to deal with mmap_min_addr over time, I think
it should be manageable to deal with the rare applications using ioperm().

Willy