On Tue, Dec 28, 2021 at 8:20 PM Michael Schmitz <schmitzmic@xxxxxxxxx> wrote: > Am 28.12.2021 um 23:08 schrieb Geert Uytterhoeven: > > On Mon, Dec 27, 2021 at 5:44 PM Niklas Schnelle <schnelle@xxxxxxxxxxxxx> wrote: > >> 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@xxxxxxxxxxxxxx/ > >> Co-developed-by: Arnd Bergmann <arnd@xxxxxxxxxx> > >> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxxxx> > >> Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx> > > > > Thanks for your patch! > > > >> --- 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. Right, makes sense. I had suggested to go the easy way and assume that each architecture would select HAS_IOPORT if any configuration supports it, but it looks like for m68k there is a clearly defined set of platforms that do. Note that for the platforms that don't set any of the three symbols, the fallback makes inb() an alias for readb() with a different argument type, so there may be m68k specific drivers that rely on this, but those would already be broken if ATARI_ROM_ISA is set. Arnd
