On Wed, 4 May 2022, Arnd Bergmann wrote: > > POWER9 is another architecture with no port I/O space[1]: > > POWER9 is just an implementation of the power architecture > that has a particular PCI host bridge. I would assume that > arch/powerpc/ would continue to set HAS_IOPORT because > it knows how to access I/O ports at compile-time. Well, yes, except I would expect POWER9_CPU (and any higher versions we eventually get) to clear HAS_IOPORT. Generic configurations (GENERIC_CPU) would set HAS_IOPORT of course, as would any lower architecture variants that do or may support port I/O (it's not clear to me if there are any that do not). Ideally a generic configuration would not issue accesses to random MMIO locations for port I/O accesses via `inb'/`outb', etc. for systems that do not support port I/O (which it now does, or at least used to until recently). Maciej
