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SubjectRe: [RFC 02/32] Kconfig: introduce HAS_IOPORT option and select it as necessary
Em Mon, 27 Dec 2021 17:42:47 +0100
Niklas Schnelle <> escreveu:

> 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:
> Co-developed-by: Arnd Bergmann <>
> Signed-off-by: Arnd Bergmann <>
> Signed-off-by: Niklas Schnelle <>


> @@ -486,6 +487,9 @@ config HAS_IOMEM
> depends on !NO_IOMEM
> default y
> +config HAS_IOPORT
> + def_bool ISA || LEGACY_PCI
> +

That doesn't sound right.

The only dependency for LEGACY_PCI is PCI. If one selects LEGACY_PCI
on an architecture that doesn't support it, this will cause problems.

Instead, HAS_IOPORT should be selected at architecture level, and
the dependency here should be just the opposite: LEGACY_API should
depends on HAS_IOPORT.


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