[PATCH v3 1/3] perf build: Add libnvme feature detection

[Ian Rogers <irogers@google.com>]

Introduce a feature check for libnvme using pkg-config so that the
tool-provided NVMe PMU can be conditionally compiled when libnvme is
available.

Add libnvme to FEATURE_TESTS_BASIC, FEATURE_DISPLAY, FEATURE_PKG_CONFIG,
and test-all.c so fast-path discovery and individual feature checks stay
consistent with the pkg-config flags used during linking.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/build/Makefile.feature       |  5 ++++-
 tools/build/feature/Makefile       |  4 ++++
 tools/build/feature/test-all.c     |  5 +++++
 tools/build/feature/test-libnvme.c | 11 +++++++++++
 tools/perf/Makefile.config         | 12 ++++++++++++
 5 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 tools/build/feature/test-libnvme.c

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 4d37d11f674c..54b51251c4c3 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -73,6 +73,7 @@ FEATURE_TESTS_BASIC :=                  \
         libbfd                          \
 	libbfd-threadsafe		\
         libelf                          \
+        libnvme                         \
         libelf-getphdrnum               \
         libelf-gelf_getnote             \
         libelf-getshdrstrndx            \
@@ -143,6 +144,7 @@ FEATURE_DISPLAY ?=              \
          libdw                  \
          glibc                  \
          libelf                 \
+         libnvme                \
          libnuma                \
          numa_num_possible_cpus \
          python-module          \
@@ -168,7 +170,8 @@ FEATURE_GROUP_MEMBERS-libbfd = libbfd-liberty libbfd-liberty-z
 FEATURE_PKG_CONFIG ?=           \
 	 babeltrace2-ctf-writer \
          libtraceevent          \
-         libtracefs
+         libtracefs             \
+         libnvme
 
 feature_pkg_config = $(eval $(feature_pkg_config_code))
 define feature_pkg_config_code
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 10340a537224..851f458163f6 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -24,6 +24,7 @@ FILES=                                          \
          test-cxa-demangle.bin                  \
          test-libcap.bin			\
          test-libelf.bin                        \
+         test-libnvme.bin                       \
          test-libelf-getphdrnum.bin             \
          test-libelf-gelf_getnote.bin           \
          test-libelf-getshdrstrndx.bin          \
@@ -147,6 +148,9 @@ $(OUTPUT)test-libcap.bin:
 $(OUTPUT)test-libelf.bin:
 	$(BUILD) -lelf
 
+$(OUTPUT)test-libnvme.bin:
+	$(BUILD) # -lnvme provided by $(FEATURE_CHECK_LDFLAGS-libnvme)
+
 $(OUTPUT)test-eventfd.bin:
 	$(BUILD)
 
diff --git a/tools/build/feature/test-all.c b/tools/build/feature/test-all.c
index 4a6890290f74..155f92efc2c8 100644
--- a/tools/build/feature/test-all.c
+++ b/tools/build/feature/test-all.c
@@ -150,6 +150,10 @@
 # include "test-libopenssl.c"
 #undef main
 
+#define main main_test_libnvme
+# include "test-libnvme.c"
+#undef main
+
 int main(int argc, char *argv[])
 {
 	main_test_python_module();
@@ -183,6 +187,7 @@ int main(int argc, char *argv[])
 	main_test_libzstd();
 	main_test_libtraceevent();
 	main_test_libopenssl();
+	main_test_libnvme();
 
 	return 0;
 }
diff --git a/tools/build/feature/test-libnvme.c b/tools/build/feature/test-libnvme.c
new file mode 100644
index 000000000000..3fefad70a680
--- /dev/null
+++ b/tools/build/feature/test-libnvme.c
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+#include <libnvme.h>
+
+int main(void)
+{
+	nvme_root_t r = nvme_scan(NULL);
+
+	if (r)
+		nvme_free_tree(r);
+	return 0;
+}
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index b4764f69f47f..d82273dadf39 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -1065,6 +1065,18 @@ ifndef NO_CAPSTONE
   endif
 endif
 
+ifndef NO_LIBNVME
+  ifeq ($(feature-libnvme), 1)
+    CFLAGS += -DHAVE_LIBNVME_SUPPORT $(shell $(PKG_CONFIG) --cflags libnvme)
+    LDFLAGS += $(shell $(PKG_CONFIG) --libs-only-L libnvme)
+    EXTLIBS += $(shell $(PKG_CONFIG) --libs-only-l libnvme)
+    $(call detected,CONFIG_LIBNVME)
+  else
+    $(warning No libnvme found, disables NVMe PMU support, please install libnvme-dev/libnvme-devel)
+    NO_LIBNVME := 1
+  endif
+endif
+
 ifdef EXTRA_TESTS
     $(call detected,CONFIG_EXTRA_TESTS)
     CFLAGS += -DHAVE_EXTRA_TESTS
-- 
2.56.1.703.gf848ed807c-goog