Hi Geert, Niklas,



Am 28.12.2021 um 23:08 schrieb Geert Uytterhoeven:

Hi Niklas,

On Mon, Dec 27, 2021 at 5:44 PM Niklas Schnelle [off-list ref] wrote:

quoted

We introduce a new HAS_IOPORT Kconfig option to gate 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. On these platforms
inb()/outb() etc are currently just stubs in asm-generic/io.h which when
called will cause a NULL pointer access which some compilers actually
detect and warn about.

The dependencies on HAS_IOPORT in drivers as well as ifdefs for
HAS_IOPORT specific sections will be added in subsequent patches on
a per subsystem basis. Then a final patch will ifdef the I/O access
functions on HAS_IOPORT thus turning any use not gated by HAS_IOPORT
into a compile-time warning.

Link: https://lore.kernel.org/lkml/CAHk-=wg80je=K7madF4e7WrRNp37e3qh6y10Svhdc7O8SZ_-8g@mail.gmail.com/ (local)
Co-developed-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>

Thanks for your patch!

quoted

--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig

@@ -16,6 +16,7 @@ config M68K
        select GENERIC_CPU_DEVICES
        select GENERIC_IOMAP
        select GENERIC_IRQ_SHOW
+       select HAS_IOPORT
        select HAVE_AOUT if MMU
        select HAVE_ASM_MODVERSIONS
        select HAVE_DEBUG_BUGVERBOSE

This looks way too broad to me: most m68k platform do not have I/O
port access support.

My gut feeling says:

    select HAS_IOPORT if PCI || ISA

but that might miss some intricate details...

In particular, this misses the Atari ROM port ISA adapter case -

	select HAS_IOPORT if PCI || ISA || ATARI_ROM_ISA

might do instead.

Cheers,

	Michael

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds