From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Julian Braha <julianbraha@gmail.com>,
Linus Walleij <linus.walleij@linaro.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Mark Rutland <mark.rutland@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
fazilyildiran@gmail.com
Subject: Re: [PATCH] ARM: fix unmet dependency on BITREVERSE for HAVE_ARCH_BITREVERSE
Date: Fri, 29 Oct 2021 23:21:18 +0100 [thread overview]
Message-ID: <YXxz3gjIUz7Lrmsn@shell.armlinux.org.uk> (raw)
In-Reply-To: <CAK8P3a1L8x48ZGhFKaMNa0MXCGrouw2EEwe9uo640bnnf=4dOA@mail.gmail.com>
On Sat, Oct 30, 2021 at 12:05:28AM +0200, Arnd Bergmann wrote:
> On Fri, Oct 29, 2021 at 10:31 PM Julian Braha <julianbraha@gmail.com> wrote:
> >
> > When ARM is enabled, and BITREVERSE is disabled,
> > Kbuild gives the following warning:
> >
> > WARNING: unmet direct dependencies detected for HAVE_ARCH_BITREVERSE
> > Depends on [n]: BITREVERSE [=n]
> > Selected by [y]:
> > - ARM [=y] && (CPU_32v7M [=n] || CPU_32v7 [=y]) && !CPU_32v6 [=n]
> >
> > This is because ARM selects HAVE_ARCH_BITREVERSE
> > without selecting BITREVERSE, despite
> > HAVE_ARCH_BITREVERSE depending on BITREVERSE.
> >
> > This unmet dependency bug was found by Kismet,
> > a static analysis tool for Kconfig. Please advise if this
> > is not the appropriate solution.
> >
> > Signed-off-by: Julian Braha <julianbraha@gmail.com>
>
> This works, but I think it would be better handled differently:
>
> The other 'select BITREVERSE' instances are for drivers that use
> bitrever(), not those that provide it.
>
> We can probably just remove the dependency. Alternatively we could
> change arch/arm/ to
>
> select HAVE_ARCH_BITREVERSE if BITREVERSE && ((CPU_32v7M ||
> CPU_32v7) && !CPU_32v6)
>
> Regardless of what we do here, note that
>
> a) the 'select' lines in CONFIG_ARM are sorted alphabetically, and
> should be kept that way
>
> b) the same probably exists on arch/mips and arch/arm64, whatever we
> do here should be the same as on the other architectures.
I think HAVE_ARCH_BITREVERSE shouldn't depend on BITREVERSE.
BITREVERSE is set when something wants the bitreverse support.
HAVE_ARCH_BITREVERSE means that the architecture has support for
the bitreverse instructions and the generic code should not be
compiled.
I don't see any reason for HAVE_ARCH_BITREVERSE to depend on
BITREVERSE.
--
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prev parent reply other threads:[~2021-10-29 22:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-29 20:31 [PATCH] ARM: fix unmet dependency on BITREVERSE for HAVE_ARCH_BITREVERSE Julian Braha
2021-10-29 22:05 ` Arnd Bergmann
2021-10-29 22:21 ` Russell King (Oracle) [this message]
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