On Fri, Dec 17, 2021 at 3:27 PM John Garry [off-list ref] wrote:

On 17/12/2021 13:52, Niklas Schnelle wrote:

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I have tested this on s390 with HAS_IOPORT=n and allyesconfig as well
as running it with defconfig. I've also been using it on my Ryzen 3990X
workstation with LEGACY_PCI=n for a few days. I do get about 60 MiB
fewer modules compared with a similar config of v5.15.8. Hard to say
which other systems might miss things of course.

I have not yet worked on the discussed IOPORT_NATIVE flag. Mostly I'm
wondering two things. For one it feels like that could be a separate
change on top since HAS_IOPORT + LEGACY_PCI is already quite big.
Secondly I'm wondering about good ways of identifying such drivers and
how much this overlaps with the ISA config flag.

I was interesting in the IOPORT_NATIVE flag (or whatever we call it) as
it solves the problem of drivers which "unconditionally do inb()/outb()
without checking the validity of the address using firmware or other
methods first" being built for (and loaded on and crashing) unsuitable
systems. Such a problem is in [0]

So if we want to support that later, then it seems that someone would
need to go back and re-edit many same driver Kconfigs – like hwon, for
example. I think it's better to avoid that and do it now.

Arnd, any opinion on that?

I'm happy to help with that effort.

I looked at the options the other day and couldn't really find any that
fell into this category, so I suggested that Niklas would skip that for the
moment. If you have a better way of finding the affected drivers,
that would be great.

       Arnd