On Fri, Apr 29, 2022 at 03:49:59PM +0200, Niklas Schnelle wrote:

We introduce a new HAS_IOPORT Kconfig option to indicate support for
I/O Port access. In a future patch HAS_IOPORT=n will disable compilation
of the I/O accessor functions inb()/outb() and friends on architectures
which can not meaningfully support legacy I/O spaces such as s390 or
where such support is optional. 

So you plan to drop inb()/outb() on architectures where I/O port space
is optional?  So even platforms that have I/O port space may not be
able to use it?

This feels like a lot of work where the main benefit is to keep
Kconfig from offering drivers that aren't of interest on s390.

Granted, there may be issues where inb()/outb() does the wrong thing
such as dereferencing null pointers when I/O port space isn't
implemented.  I think that's a defect in inb()/outb() and could be
fixed there.

Bjorn