From: Ian Rogers <irogers@google.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: "Peter Zijlstra" <peterz@infradead.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Arnaldo Carvalho de Melo" <acme@kernel.org>,
"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
"Jiri Olsa" <jolsa@kernel.org>,
"Adrian Hunter" <adrian.hunter@intel.com>,
"John Garry" <john.g.garry@oracle.com>,
"Will Deacon" <will@kernel.org>,
"James Clark" <james.clark@linaro.org>,
"Mike Leach" <mike.leach@linaro.org>,
"Leo Yan" <leo.yan@linux.dev>,
"Suzuki K Poulose" <suzuki.poulose@arm.com>,
"Yicong Yang" <yangyicong@hisilicon.com>,
"Jonathan Cameron" <jonathan.cameron@huawei.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Darren Hart" <dvhart@infradead.org>,
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"André Almeida" <andrealmeid@igalia.com>,
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"Yuzhuo Jing" <yuzhuo@google.com>,
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"Andi Kleen" <ak@linux.intel.com>,
"Howard Chu" <howardchu95@gmail.com>,
"Zecheng Li" <zecheng@google.com>, tanze <tanze@kylinos.cn>,
"Gabriele Monaco" <gmonaco@redhat.com>,
"GuoHan Zhao" <zhaoguohan@kylinos.cn>,
"Markus Elfring" <Markus.Elfring@web.de>,
"Colin Ian King" <colin.i.king@gmail.com>,
"Kan Liang" <kan.liang@linux.intel.com>,
"Dr. David Alan Gilbert" <linux@treblig.org>,
"Jean-Philippe Romain" <jean-philippe.romain@foss.st.com>,
"Yang Li" <yang.lee@linux.alibaba.com>,
linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v1 0/5] Remove NO_AUXTRACE build option
Date: Tue, 11 Nov 2025 10:01:40 -0800 [thread overview]
Message-ID: <CAP-5=fW4XSL_tAD9-BzG9ceUJSr005bWi3Q1-kiJ_xyiHJZggg@mail.gmail.com> (raw)
In-Reply-To: <aRLV50z1L9A3YRFF@google.com>
On Mon, Nov 10, 2025 at 10:21 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Hi Ian,
>
> On Sun, Nov 09, 2025 at 05:31:47PM -0800, Ian Rogers wrote:
> > Switch the __get_cpuid feature for intel-pt to use the provided cpuid
> > function in perf, this removes the need for NO_AUXTRACE when the
> > feature detection fails. Remove the now unnecessary feature
> > detection. Remove NO_AUXTRACE as it just builds a more broken version
>
> Can you please elaborate what the broken part is?
Sure. I'll summarize what alters in patch 4. NO_AUXTRACE is
controlling 3 main things:
* set up of aux options for PMUs (code in the arch directory)
* ARM: coresight and SPE
* Intel: BTS and PT
* PowerPC: VPA DTL
* S390: cpumsf
* support for decoding aux events (common code that can be
cross-compiled assuming other library dependencies are available)
* ARM: coresight
* HiSi: PTT decoder
* Intel: BTS and PT
* PowerPC: VPA DTL
* S390: cpumsf
* Tool support for aux buffers (common shared builtin code):
* perf record: aux options for events, snapshot, aux-sample
* perf inject: aux events will fail the entire perf inject command
So somebody with a NO_AUXTRACE build would generally experience a very
sad perf command. Having the option made sense when there were feature
tests that could fail, but possibly that should have just controlled
not compiling intel-pt. Having the option is extra burden on
developers/maintainers, as shown in my comment:
> This was prompted by needing to make a v2 patch set of:
> https://lore.kernel.org/lkml/20251107170712.2302714-1-irogers@google.com/
> due to a broken NO_AUXTRACE configuration.
Somebody may have been using NO_AUXTRACE as a proxy for not having
some library, but I don't see that in the code. If this is the case we
should add the appropriate feature test, ..
Not having NO_AUXTRACE may have been a bug work around for someone, in
which case we should work to fix the bug. Again, I don't know of this
case and don't see it in the code.
Thanks,
Ian
> Thanks,
> Namhyung
next prev parent reply other threads:[~2025-11-11 18:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-10 1:31 [PATCH v1 0/5] Remove NO_AUXTRACE build option Ian Rogers
2025-11-10 1:31 ` [PATCH v1 1/5] perf intel-pt: Use the perf provided "cpuid.h" Ian Rogers
2025-11-10 1:31 ` [PATCH v1 2/5] perf build: Don't add NO_AUXTRACE if missing feature-get_cpuid Ian Rogers
2025-11-10 1:31 ` [PATCH v1 3/5] tool build: Remove __get_cpuid feature test Ian Rogers
2025-11-10 1:31 ` [PATCH v1 4/5] perf build: Remove NO_AUXTRACE build option Ian Rogers
2025-11-10 1:31 ` [PATCH v1 5/5] perf auxtrace: Remove errno.h from auxtrace.h and fix transitive dependencies Ian Rogers
2025-11-11 6:21 ` [PATCH v1 0/5] Remove NO_AUXTRACE build option Namhyung Kim
2025-11-11 18:01 ` Ian Rogers [this message]
2025-11-12 9:21 ` James Clark
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