linux-kernel - Re: [RFC 25/32] watchdog: Kconfig: add HAS

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Date:   Tue, 28 Dec 2021 10:58:31 +0100
From:   Niklas Schnelle <schnelle@...ux.ibm.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Arnd Bergmann <arnd@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        John Garry <john.garry@...wei.com>,
        Nick Hu <nickhu@...estech.com>,
        Greentime Hu <green.hu@...il.com>,
        Vincent Chen <deanbo422@...il.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>, Guo Ren <guoren@...nel.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-csky@...r.kernel.org, linux-watchdog@...r.kernel.org
Subject: Re: [RFC 25/32] watchdog: Kconfig: add HAS_IOPORT dependencies

On Mon, 2021-12-27 at 10:03 -0800, Guenter Roeck wrote:
> On 12/27/21 8:43 AM, Niklas Schnelle wrote:
> > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
> > not being declared. We thus need to add HAS_IOPORT as dependency for
> > those drivers using them.
> > 
> 
> How is the need for HAS_IOPORT determined, when exactly is it needed,
> and when not ?

I mostly used "make allyesconfig" on s390 with the accessors ifdeffed
out (i.e. patch 32) to find where the I/O port accesses were compiled
in. This means that it doesn't find drivers which pull in a HAS_IOPORT
dependency transitively e.g. by depending on x86 or ACPI. It should get
those that use e.g. "|| COMPILE_TEST" though. This might not be ideal
but on the other hand it should catch all those drivers that currently
built with known broken code.

> 
> $ git grep -E "inb|inw" drivers/watchdog/ | cut -f1 -d: | sort -u
> drivers/watchdog/acquirewdt.c
> drivers/watchdog/advantechwdt.c
> 
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