perf build: Make libunwind opt-in rather than opt-out

Having multiple unwinding libraries makes the perf code harder to
understand and we have unused/untested code paths.

Perf made BPF support an opt-out rather than opt-in feature. As libbpf
has a libelf dependency, elfutils that provides libelf will also
provide libdw. When libdw is present perf will use libdw unwinding
rather than libunwind unwinding even if libunwind support is compiled
in.

Rather than have libunwind built into perf and never used, explicitly
disable the support and make it opt-in.

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/r/20241028193619.247727-1-irogers@google.com
Closes: https://lore.kernel.org/linux-perf-users/CAP-5=fUXkp-d7gkzX4eF+nbjb2978dZsiHZ9abGHN=BN1qAcbg@mail.gmail.com/
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Ian Rogers 2024-10-28 12:36:19 -07:00 committed by Namhyung Kim
parent aa5c90601b
commit 13e17c9ff4
3 changed files with 8 additions and 4 deletions

View File

@ -95,6 +95,10 @@ ifneq ($(SRCARCH),$(filter $(SRCARCH),x86 arm arm64 powerpc s390 csky riscv loon
NO_LIBDW_DWARF_UNWIND := 1
endif
ifneq ($(LIBUNWIND),1)
NO_LIBUNWIND := 1
endif
ifeq ($(LIBUNWIND_LIBS),)
NO_LIBUNWIND := 1
endif

View File

@ -52,7 +52,7 @@ include ../scripts/utilities.mak
#
# Define NO_LIBELF if you do not want libelf dependency (e.g. cross-builds)
#
# Define NO_LIBUNWIND if you do not want libunwind dependency for dwarf
# Define LIBUNWIND if you do not want libunwind dependency for dwarf
# backtrace post unwind.
#
# Define NO_BACKTRACE if you do not want stack backtrace debug feature

View File

@ -81,7 +81,7 @@ make_no_gtk2 := NO_GTK2=1
make_no_ui := NO_SLANG=1 NO_GTK2=1
make_no_demangle := NO_DEMANGLE=1
make_no_libelf := NO_LIBELF=1
make_no_libunwind := NO_LIBUNWIND=1
make_libunwind := LIBUNWIND=1
make_no_libdw_dwarf_unwind := NO_LIBDW_DWARF_UNWIND=1
make_no_backtrace := NO_BACKTRACE=1
make_no_libcapstone := NO_CAPSTONE=1
@ -121,7 +121,7 @@ make_static := LDFLAGS=-static NO_PERF_READ_VDSO32=1 NO_PERF_READ_VDSOX3
# all the NO_* variable combined
make_minimal := NO_LIBPERL=1 NO_LIBPYTHON=1 NO_GTK2=1
make_minimal += NO_DEMANGLE=1 NO_LIBELF=1 NO_LIBUNWIND=1 NO_BACKTRACE=1
make_minimal += NO_DEMANGLE=1 NO_LIBELF=1 NO_BACKTRACE=1
make_minimal += NO_LIBNUMA=1 NO_LIBAUDIT=1 NO_LIBBIONIC=1
make_minimal += NO_LIBDW_DWARF_UNWIND=1 NO_AUXTRACE=1 NO_LIBBPF=1
make_minimal += NO_LIBCRYPTO=1 NO_SDT=1 NO_JVMTI=1 NO_LIBZSTD=1
@ -153,7 +153,7 @@ run += make_no_gtk2
run += make_no_ui
run += make_no_demangle
run += make_no_libelf
run += make_no_libunwind
run += make_libunwind
run += make_no_libdw_dwarf_unwind
run += make_no_backtrace
run += make_no_libcapstone