Re: [linux-next:master 6577/7309] drivers/perf/arm_pmuv3.c:44:2: error: use of undeclared identifier 'PERF_MAP_ALL_UNSUPPORTED' - Zaid Al-Bassam

From: Zaid Al-Bassam <zalbassam@google.com>
To: Marc Zyngier <maz@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Will Deacon <will@kernel.org>,
	kernel test robot <lkp@intel.com>,
	 llvm@lists.linux.dev, oe-kbuild-all@lists.linux.dev,
	 Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [linux-next:master 6577/7309] drivers/perf/arm_pmuv3.c:44:2: error: use of undeclared identifier 'PERF_MAP_ALL_UNSUPPORTED'
Date: Tue, 28 Mar 2023 12:37:42 -0400	[thread overview]
Message-ID: <CALBRaFmmTZSZ+pm-=QKh5x_Pp8iMX_zdF50-u9HPdweq24jmzQ@mail.gmail.com> (raw)
In-Reply-To: <86o7ocx51a.wl-maz@kernel.org>

Thank you Marc.

Arnd, Do you want to change your patch to drop [1], or should I create
a new patch? Btw, Thank you for the patch.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/commit/?id=3b16f6268e66

Zaid

On Tue, Mar 28, 2023 at 11:35 AM Marc Zyngier <maz@kernel.org> wrote:
>
> On Tue, 28 Mar 2023 16:29:07 +0100,
> "Arnd Bergmann" <arnd@arndb.de> wrote:
> >
> > On Tue, Mar 28, 2023, at 14:21, Will Deacon wrote:
> > > On Tue, Mar 28, 2023 at 04:01:49PM +0800, kernel test robot wrote:
> >
> > > I think the Kconfig warning is relevant here:
> > >
> > >> Kconfig warnings: (for reference only)
> > >>    WARNING: unmet direct dependencies detected for ARM_PMUV3
> > >>    Depends on [n]: PERF_EVENTS [=y] && HW_PERF_EVENTS [=n] && (ARM [=y] && CPU_V7 [=y] || ARM64)
> > >>    Selected by [y]:
> > >>    - ARCH_VIRT [=y] && ARCH_MULTI_V7 [=y] && PERF_EVENTS [=y]
> > >
> > > Since we're selecting an option which has its own dependencies. I think
> > > the easiest bet is to invert the linkage so that PMUV3 has a dependency
> > > on ARCH_VIRT for 32-bit Arm (diff below).
> > >
> > > Marc, Zaid -- what do you think?
> >
> > I think dropping the 'select' is best, as this is still a user-visible
> > option. How about this instead:
> >
> > --- a/drivers/perf/Kconfig
> > +++ b/drivers/perf/Kconfig
> > @@ -103,7 +103,7 @@ config ARM_SMMU_V3_PMU
> >  config ARM_PMUV3
> >         depends on HW_PERF_EVENTS && ((ARM && CPU_V7) || ARM64)
> >         bool "ARM PMUv3 support" if !ARM64
> > -       default ARM64
> > +       default ARM64 || ARCH_VIRT
> >           help
> >           Say y if you want to use the ARM performance monitor unit (PMU)
> >           version 3. The PMUv3 is the CPU performance monitors on ARMv8
> >
> > This way, it's still enabled by default for most people, but
> > there is no dependency problem and it's also possible to
> > turn it off.
>
> [removing my old self from the Cc list]
>
> Either way work for me. Or even drop that patch altogether and let
> people select PMUv3 if they really want it. This is extremely niche
> anyway, and most people won't care.
>
> Thanks,
>
>         M.
>
> --
> Without deviation from the norm, progress is not possible.