Messages in this thread | | | Date | Wed, 4 May 2022 15:24:39 +0100 (BST) | From | "Maciej W. Rozycki" <> | Subject | Re: [RFC v2 25/39] pcmcia: add HAS_IOPORT dependencies |
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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
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