From: David Laight <David.Laight@ACULAB.COM>
To: 'Andy Shevchenko' <andriy.shevchenko@linux.intel.com>,
Valentin Schneider <valentin.schneider@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>
Subject: RE: [PATCH v1] sched/topology: Make compiler happy about unused constant definitions
Date: Tue, 25 Aug 2020 10:23:05 +0000 [thread overview]
Message-ID: <8dbf0f1e60c848f0abafd5fa0490ff70@AcuMS.aculab.com> (raw)
In-Reply-To: <20200825082636.GQ1891694@smile.fi.intel.com>
From: Andy Shevchenko
> Sent: 25 August 2020 09:27
>
> On Mon, Aug 24, 2020 at 06:09:41PM +0100, Valentin Schneider wrote:
> > On 24/08/20 16:39, Andy Shevchenko wrote:
> > > Compilation of almost each file ends up with
> > >
> > > In file included from .../include/linux/energy_model.h:10,
> > > from .../include/linux/device.h:16,
> > > from .../drivers/spi/spi.c:8:
> > > .../include/linux/sched/topology.h:30:27: warning: ‘SD_DEGENERATE_GROUPS_MASK’ defined but not
> used [-Wunused-const-variable=]
> > > 30 | static const unsigned int SD_DEGENERATE_GROUPS_MASK =
> > > | ^~~~~~~~~~~~~~~~~~~~~~~~~
> > > ...
> > >
> > > Make compiler happy by annotating the static constants with __maybwe_unused.
> > >
> >
> > That should see some use as long as the build is for SMP. This whole region
> > is guarded by #ifdef CONFIG_SMP, so an !SMP build shouldn't trigger this.
>
> Isn't SMP is default for most of the kernel builds?
> And honestly I didn't get the purpose of this comment.
The real fix is to not use 'static const' in C.
IIRC it is still a memory location (that can be patched) not
a compile time constant.
David
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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-08-25 10:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-24 15:39 Andy Shevchenko
2020-08-24 17:09 ` Valentin Schneider
2020-08-25 8:26 ` Andy Shevchenko
2020-08-25 9:03 ` Valentin Schneider
2020-08-25 10:12 ` Valentin Schneider
2020-08-25 11:24 ` Andy Shevchenko
2020-08-25 11:26 ` Andy Shevchenko
2020-08-25 11:32 ` Andy Shevchenko
2020-08-25 12:00 ` Valentin Schneider
2020-08-25 12:38 ` Andy Shevchenko
2020-08-25 10:23 ` David Laight [this message]
2020-08-25 11:30 ` 'Andy Shevchenko'
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