linux-kernel - Re: [PATCH v4 02/14] perf evsel: Refactor evsel__set_config_if

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Message-ID: <aWe6igmKMq25GJP9@x1>
Date: Wed, 14 Jan 2026 12:47:22 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: James Clark <james.clark@...aro.org>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Mike Leach <mike.leach@...aro.org>,
	John Garry <john.g.garry@...cle.com>, Will Deacon <will@...nel.org>,
	Leo Yan <leo.yan@...ux.dev>, linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org, coresight@...ts.linaro.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 02/14] perf evsel: Refactor
 evsel__set_config_if_unset() arguments

On Wed, Jan 14, 2026 at 12:14:43PM +0000, James Clark wrote:
> On 13/01/2026 10:13 pm, Arnaldo Carvalho de Melo wrote:
> > On Mon, Dec 22, 2025 at 03:14:27PM +0000, James Clark wrote:
> > > Make the evsel argument first to match the other evsel__* functions
> > > and remove the redundant pmu argument, which can be accessed via evsel.

> > I haven't checked if this is the exactly where this takes place but
> > should be in this series, 32-bit build is broken:

> >     3: almalinux:9-i386WARNING: image platform (linux/386) does not match the expected platform (linux/amd64)
> > WARNING: image platform (linux/386) does not match the expected platform (linux/amd64)
> >      21.72 almalinux:9-i386              : FAIL gcc version 11.4.1 20231218 (Red Hat 11.4.1-3) (GCC)
> >       1378 |         perf_pmu__format_pack(&bits, val, vp, /*zero=*/true);
> >            |                               ^~~~~
> >            |                               |
> >            |                               u64 * {aka long long unsigned int *}
> >      In file included from util/evsel.h:14,
> >                       from util/evsel.c:38:
> >      util/pmu.h:282:43: note: expected ‘long unsigned int *’ but argument is of type ‘u64 *’ {aka ‘long long unsigned int *’}
> >        282 | void perf_pmu__format_pack(unsigned long *format, __u64 value, __u64 *v,
> >            |                            ~~~~~~~~~~~~~~~^~~~~~
 
> > What I have is in perf-tools-next/tmp.perf-tools-next BTW, I'll try and
> > fix this tomorrow if you don't do it first. :-)
 
> Taking a look, but I'm wondering if this is already not working properly.
> There are existing "unsigned long"s in pmu.c that operate on the config bits
> which is what I copied.
 
> On this target an unsigned long is 32bits but struct
> perf_event_attr->configs are __u64. So it looks like it might leave the top
> bits unset sometimes.
 
> I'll look at a fix for that which should fix the compilation error at the
> same time.
 
> Another question is, do we actually care about this platform?

It failed for other 32-bit platforms too, so the question is if we care
about 32-bit at all.

- Arnaldo