From: Namhyung Kim <namhyung@kernel•org>
To: Ian Rogers <irogers@google•com>
Cc: 9erthalion6@gmail•com, acme@kernel•org, adrian.hunter@intel•com,
alex@ghiti•fr, alexander.shishkin@linux•intel.com,
andrew.jones@oss•qualcomm.com, aou@eecs•berkeley.edu,
atrajeev@linux•ibm.com, blakejones@google•com, ctshao@google•com,
dapeng1.mi@linux•intel.com, howardchu95@gmail•com,
james.clark@linaro•org, john.g.garry@oracle•com,
jolsa@kernel•org, leo.yan@linux•dev, libunwind-devel@nongnu•org,
linux-arm-kernel@lists•infradead.org,
linux-kernel@vger•kernel.org, linux-perf-users@vger•kernel.org,
linux-riscv@lists•infradead.org, mingo@redhat•com,
palmer@dabbelt•com, peterz@infradead•org, pjw@kernel•org,
shimin.guo@skydio•com, tglozar@redhat•com, tmricht@linux•ibm.com,
will@kernel•org, amadio@gentoo•org, yuzhuo@google•com
Subject: Re: [PATCH v1 0/2] perf build: Remove libunwind support
Date: Thu, 26 Mar 2026 15:51:19 -0700 [thread overview]
Message-ID: <acW4Z2KJbyPZM1SG@google.com> (raw)
In-Reply-To: <20260321234220.848859-1-irogers@google.com>
On Sat, Mar 21, 2026 at 04:42:18PM -0700, Ian Rogers wrote:
> libunwind support exists for "--call-graph dwarf", however, libunwind
> support has been opt-in rather than opt-out since Linux v6.13 as libdw
> is preferred - commit 13e17c9ff49119aa ("perf build: Make libunwind
> opt-in rather than opt-out"). A problem with the libdw support was
> that it was slow, an issue fixed in Linux v7.0 in commit 6b2658b3f36a
> ("perf unwind-libdw: Don't discard loaded ELF/DWARF after every
> unwind"). As such libunwind support is now unnecessary.
>
> The patch series:
> https://lore.kernel.org/lkml/20260305221927.3237145-1-irogers@google.com/
> looked to make the libunwind support in perf similar to the libdw
> support, allow cross-architecture unwinding, etc. This was motivated
> by the perf regs conventions being altered by the addition of x86 APX
> support:
> https://lore.kernel.org/lkml/20260209072047.2180332-1-dapeng1.mi@linux.intel.com/
> It is necessary to translate the library's notion of registers to the
> perf register convention so that the stack unwinding state can be
> initialized. On this series it was stated that removing libunwind
> support from perf should be an option, rather than updating support:
> https://lore.kernel.org/lkml/abxs-2rozL1tBEO1@google.com/
> This was also what motivated making libunwind opt-in rather than
> opt-out.
>
> Given that 7 minor releases have happened with libunwind "deprecated"
> by making it opt-in, let's remove the libunwind support. There doesn't
> appear to be any disagreement to this on the mailing list.
I'm not sure if we want to remove it now. I think we need more time to
verify libdw unwinding is stable and fast enough. Also maybe we can
add build- or run-time warning when people try to use libunwind.
Thanks,
Namhyung
>
> Ian Rogers (2):
> perf build: Remove libunwind support
> tools build: Remove libunwind feature tests
>
> tools/build/feature/Makefile | 31 -
> tools/build/feature/test-libunwind-aarch64.c | 27 -
> tools/build/feature/test-libunwind-arm.c | 28 -
> .../test-libunwind-debug-frame-aarch64.c | 17 -
> .../feature/test-libunwind-debug-frame-arm.c | 17 -
> .../feature/test-libunwind-debug-frame.c | 17 -
> tools/build/feature/test-libunwind-x86.c | 28 -
> tools/build/feature/test-libunwind-x86_64.c | 28 -
> tools/build/feature/test-libunwind.c | 28 -
> tools/perf/Documentation/perf-check.txt | 1 -
> tools/perf/Documentation/perf-config.txt | 4 +-
> tools/perf/Documentation/perf-record.txt | 2 +-
> tools/perf/Makefile.config | 163 +---
> tools/perf/Makefile.perf | 3 -
> tools/perf/arch/arm/util/Build | 1 -
> tools/perf/arch/arm/util/unwind-libunwind.c | 50 --
> tools/perf/arch/arm64/util/Build | 1 -
> tools/perf/arch/arm64/util/unwind-libunwind.c | 17 -
> tools/perf/arch/loongarch/util/Build | 1 -
> .../arch/loongarch/util/unwind-libunwind.c | 82 --
> tools/perf/arch/mips/util/Build | 1 -
> tools/perf/arch/mips/util/unwind-libunwind.c | 22 -
> tools/perf/arch/powerpc/util/Build | 1 -
> .../perf/arch/powerpc/util/unwind-libunwind.c | 92 --
> tools/perf/arch/x86/util/Build | 1 -
> tools/perf/arch/x86/util/unwind-libunwind.c | 115 ---
> tools/perf/builtin-check.c | 1 -
> tools/perf/builtin-report.c | 4 +-
> tools/perf/tests/make | 2 -
> tools/perf/util/Build | 5 -
> tools/perf/util/callchain.c | 2 +-
> tools/perf/util/dso.h | 6 -
> tools/perf/util/libunwind/arm64.c | 40 -
> tools/perf/util/libunwind/x86_32.c | 41 -
> tools/perf/util/maps.c | 47 +-
> tools/perf/util/maps.h | 6 -
> tools/perf/util/thread.c | 40 +-
> tools/perf/util/thread.h | 1 -
> tools/perf/util/unwind-libunwind-local.c | 832 ------------------
> tools/perf/util/unwind-libunwind.c | 92 --
> tools/perf/util/unwind.h | 41 +-
> 41 files changed, 19 insertions(+), 1919 deletions(-)
> delete mode 100644 tools/build/feature/test-libunwind-aarch64.c
> delete mode 100644 tools/build/feature/test-libunwind-arm.c
> delete mode 100644 tools/build/feature/test-libunwind-debug-frame-aarch64.c
> delete mode 100644 tools/build/feature/test-libunwind-debug-frame-arm.c
> delete mode 100644 tools/build/feature/test-libunwind-debug-frame.c
> delete mode 100644 tools/build/feature/test-libunwind-x86.c
> delete mode 100644 tools/build/feature/test-libunwind-x86_64.c
> delete mode 100644 tools/build/feature/test-libunwind.c
> delete mode 100644 tools/perf/arch/arm/util/unwind-libunwind.c
> delete mode 100644 tools/perf/arch/arm64/util/unwind-libunwind.c
> delete mode 100644 tools/perf/arch/loongarch/util/unwind-libunwind.c
> delete mode 100644 tools/perf/arch/mips/util/unwind-libunwind.c
> delete mode 100644 tools/perf/arch/powerpc/util/unwind-libunwind.c
> delete mode 100644 tools/perf/arch/x86/util/unwind-libunwind.c
> delete mode 100644 tools/perf/util/libunwind/arm64.c
> delete mode 100644 tools/perf/util/libunwind/x86_32.c
> delete mode 100644 tools/perf/util/unwind-libunwind-local.c
> delete mode 100644 tools/perf/util/unwind-libunwind.c
>
> --
> 2.53.0.959.g497ff81fa9-goog
>
next prev parent reply other threads:[~2026-03-26 22:51 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-24 14:29 [RFC PATCH v1 0/7] perf libunwind multiple remote support Ian Rogers
2026-02-24 14:29 ` [RFC PATCH v1 1/7] tools build: Deduplicate test-libunwind for different architectures Ian Rogers
2026-02-24 14:29 ` [RFC PATCH v1 2/7] perf build: Be more programmatic when setting up libunwind variables Ian Rogers
2026-02-24 14:29 ` [RFC PATCH v1 3/7] perf build loongarch: Remove reference to missing file Ian Rogers
2026-02-24 14:29 ` [RFC PATCH v1 4/7] perf unwind-libunwind: Make libunwind register reading cross platform Ian Rogers
2026-02-24 14:29 ` [RFC PATCH v1 5/7] perf unwind-libunwind: Move flush/finish access out of local Ian Rogers
2026-02-24 14:29 ` [RFC PATCH v1 7/7] perf unwind-libunwind: Add RISC-V libunwind support Ian Rogers
2026-02-25 21:08 ` Andrew Jones
2026-02-26 1:34 ` Ian Rogers
2026-03-05 22:19 ` [PATCH v2 0/8] perf libunwind multiple remote support Ian Rogers
2026-03-05 22:19 ` [PATCH v2 1/8] perf unwind: Refactor get_entries to allow dynamic libdw/libunwind selection Ian Rogers
2026-03-31 20:38 ` Arnaldo Carvalho de Melo
2026-03-31 20:42 ` Arnaldo Carvalho de Melo
2026-03-31 21:21 ` Ian Rogers
2026-03-05 22:19 ` [PATCH v2 2/8] perf build loongarch: Remove reference to missing file Ian Rogers
2026-03-30 21:05 ` Arnaldo Carvalho de Melo
2026-03-31 17:01 ` Ian Rogers
2026-03-05 22:19 ` [PATCH v2 3/8] tools build: Deduplicate test-libunwind for different architectures Ian Rogers
2026-03-30 21:08 ` Arnaldo Carvalho de Melo
2026-03-05 22:19 ` [PATCH v2 4/8] perf build: Be more programmatic when setting up libunwind variables Ian Rogers
2026-03-05 22:19 ` [PATCH v2 5/8] perf unwind-libunwind: Make libunwind register reading cross platform Ian Rogers
2026-03-05 22:19 ` [PATCH v2 6/8] perf unwind-libunwind: Move flush/finish access out of local Ian Rogers
2026-03-05 22:19 ` [PATCH v2 8/8] perf unwind-libunwind: Add RISC-V libunwind support Ian Rogers
2026-03-19 21:39 ` [PATCH v2 0/8] perf libunwind multiple remote support Namhyung Kim
2026-03-21 3:06 ` Ian Rogers
2026-03-21 8:20 ` Guilherme Amadio
2026-03-21 23:42 ` [PATCH v1 0/2] perf build: Remove libunwind support Ian Rogers
2026-03-21 23:42 ` [PATCH v1 1/2] " Ian Rogers
2026-03-21 23:42 ` [PATCH v1 2/2] tools build: Remove libunwind feature tests Ian Rogers
2026-03-26 22:51 ` Namhyung Kim [this message]
2026-03-26 23:14 ` [PATCH v1 0/2] perf build: Remove libunwind support Ian Rogers
2026-03-27 20:07 ` Arnaldo Carvalho de Melo
2026-03-27 20:37 ` Ian Rogers
2026-03-27 20:41 ` Ian Rogers
2026-03-27 21:08 ` Arnaldo Carvalho de Melo
2026-03-30 18:49 ` Arnaldo Carvalho de Melo
2026-04-04 5:40 ` [PATCH v3 0/8] perf libunwind multiple remote support Ian Rogers
2026-04-04 5:40 ` [PATCH v3 1/8] perf unwind: Refactor get_entries to allow dynamic libdw/libunwind selection Ian Rogers
2026-04-04 5:40 ` [PATCH v3 2/8] perf build loongarch: Remove reference to missing file Ian Rogers
2026-04-04 5:40 ` [PATCH v3 3/8] tools build: Deduplicate test-libunwind for different architectures Ian Rogers
2026-04-04 5:40 ` [PATCH v3 4/8] perf build: Be more programmatic when setting up libunwind variables Ian Rogers
2026-04-04 5:40 ` [PATCH v3 5/8] perf unwind-libunwind: Make libunwind register reading cross platform Ian Rogers
2026-04-04 5:40 ` [PATCH v3 6/8] perf unwind-libunwind: Move flush/finish access out of local Ian Rogers
2026-04-04 5:40 ` [PATCH v3 8/8] perf unwind-libunwind: Add RISC-V libunwind support Ian Rogers
2026-04-11 1:04 ` [PATCH v3 0/8] perf libunwind multiple remote support Ian Rogers
2026-04-12 19:18 ` Arnaldo Carvalho de Melo
2026-04-13 2:47 ` [PATCH v4 " Ian Rogers
2026-04-13 2:47 ` [PATCH v4 1/8] perf unwind: Refactor get_entries to allow dynamic libdw/libunwind selection Ian Rogers
2026-04-30 3:25 ` patchwork-bot+linux-riscv
2026-04-13 2:47 ` [PATCH v4 2/8] perf build loongarch: Remove reference to missing file Ian Rogers
2026-04-13 2:48 ` [PATCH v4 3/8] tools build: Deduplicate test-libunwind for different architectures Ian Rogers
2026-04-13 2:48 ` [PATCH v4 4/8] perf build: Be more programmatic when setting up libunwind variables Ian Rogers
2026-04-13 2:48 ` [PATCH v4 5/8] perf unwind-libunwind: Make libunwind register reading cross platform Ian Rogers
2026-04-13 2:48 ` [PATCH v4 6/8] perf unwind-libunwind: Move flush/finish access out of local Ian Rogers
2026-04-13 2:48 ` [PATCH v4 8/8] perf unwind-libunwind: Add RISC-V libunwind support Ian Rogers
2026-04-13 21:01 ` [PATCH v4 0/8] perf libunwind multiple remote support Ian Rogers
2026-05-13 23:31 ` [PATCH v5 0/7] " Ian Rogers
2026-05-13 23:31 ` [PATCH v5 1/7] perf unwind: Refactor get_entries to allow dynamic libdw/libunwind selection Ian Rogers
2026-05-15 0:12 ` Arnaldo Carvalho de Melo
2026-05-15 11:27 ` Arnaldo Carvalho de Melo
2026-05-15 16:30 ` Ian Rogers
2026-05-13 23:31 ` [PATCH v5 2/7] tools build: Deduplicate test-libunwind for different architectures Ian Rogers
2026-05-13 23:31 ` [PATCH v5 3/7] perf build: Be more programmatic when setting up libunwind variables Ian Rogers
2026-05-13 23:31 ` [PATCH v5 4/7] perf unwind-libunwind: Make libunwind register reading cross platform Ian Rogers
2026-05-15 19:23 ` Arnaldo Carvalho de Melo
2026-05-15 19:38 ` Ian Rogers
2026-05-15 20:48 ` Arnaldo Carvalho de Melo
2026-05-17 17:23 ` Ian Rogers
2026-05-13 23:31 ` [PATCH v5 5/7] perf unwind-libunwind: Move flush/finish access out of local Ian Rogers
2026-05-13 23:31 ` [PATCH v5 7/7] perf unwind-libunwind: Add RISC-V libunwind support Ian Rogers
2026-05-14 16:51 ` [PATCH v5 0/7] perf libunwind multiple remote support Ian Rogers
2026-05-15 0:01 ` Arnaldo Carvalho de Melo
2026-05-15 0:28 ` Arnaldo Carvalho de Melo
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