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[222.155.5.102]) by smtp.gmail.com with ESMTPSA id cm20sm18920963pjb.28.2021.12.28.17.20.41 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 28 Dec 2021 17:21:06 -0800 (PST) Subject: Re: [RFC 02/32] Kconfig: introduce HAS_IOPORT option and select it as necessary To: Geert Uytterhoeven , Niklas Schnelle References: <20211227164317.4146918-1-schnelle@linux.ibm.com> <20211227164317.4146918-3-schnelle@linux.ibm.com> Cc: Arnd Bergmann , Bjorn Helgaas , John Garry , Nick Hu , Greentime Hu , Vincent Chen , Paul Walmsley , Palmer Dabbelt , Albert Ou , Guo Ren , Dinh Nguyen , Chris Zankel , Karol Gugala , Jeff Dike , Yoshinori Sato , Brian Cain , Heiko Carstens , Richard Henderson , Ivan Kokshaysky , Matt Turner , Vineet Gupta , Russell King , Catalin Marinas , Will Deacon , Michal Simek , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Rich Felker , "David S. Miller" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-pci@vger.kernel.org, linux-riscv@lists.infradead.org, linux-csky@vger.kernel.org, linux-xtensa@linux-xtensa.org, openrisc@lists.librecores.org, linux-s390@vger.kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, Greg Ungerer From: Michael Schmitz Message-ID: Date: Wed, 29 Dec 2021 14:20:38 +1300 User-Agent: Mozilla/5.0 (X11; Linux ppc; rv:45.0) Gecko/20100101 Icedove/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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@mail.gmail.com/ >> Co-developed-by: Arnd Bergmann >> Signed-off-by: Arnd Bergmann >> Signed-off-by: Niklas Schnelle > > 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. 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 >