Re: [RFC 02/32] Kconfig: introduce HAS_IOPORT option and select it as necessary
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From: Mauro Carvalho Chehab <mchehab@kernel.org>
Date: 2021-12-28 16:32:24
Also in:
linux-alpha, linux-arch, linux-m68k, linux-mips, linux-pci, linux-riscv, linux-s390, linux-sh, lkml, sparclinux
Em Mon, 27 Dec 2021 17:42:47 +0100 Niklas Schnelle [off-list ref] 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: 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>
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@@ -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. Thanks, Mauro