[PATCH v2] Fix build failure due to btf on Linux < 6.0

Giulio Benetti
2026-03-12T20:39:11Z

With commit:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6089fb325cf737eeb2c4d236c94697112ca860da
enum BTF_KIND_ENUM64 has been firstly introduced and this is the latest
BTF_KIND_* enumaration to be added to libtraceevent. So let's check
in runtime, both in Makefile and meson, if BTF_KIND_ENUM64 does exist.
If it's not there let's disable btf support.

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Co-authored-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
---
V1->V2:
* fixed meson check and all bft C source
---
Makefile | 28 +++++++++++++++++++++-------
src/meson.build | 12 ++++++++++++
src/trace-btf.c | 31 +++++++++++++++++++++++++++++--
3 files changed, 62 insertions(+), 9 deletions(-)

diff --git a/Makefile b/Makefile
index e1a10a0..bd88a98 100644
--- a/Makefile
+++ b/Makefile
@@ -27,6 +27,13 @@ $(call allow-override,PKG_CONFIG,pkg-config)
$(call allow-override,LD_SO_CONF_PATH,/etc/ld.so.conf.d/)
$(call allow-override,LDCONFIG,ldconfig)

+# Set compile option CFLAGS
+ifdef EXTRA_CFLAGS
+ CFLAGS ?= $(EXTRA_CFLAGS)
+else
+ CFLAGS ?= -g -Wall
+endif
+
EXT = -std=gnu99
INSTALL = install

@@ -37,6 +44,20 @@ INSTALL = install
DESTDIR ?=
DESTDIR_SQ = '$(subst ','\'',$(DESTDIR))'

+test-build = $(if $(shell sh -c 'echo "$(1)" | tee /tmp/t.c| \
+ $(CC) -o /dev/null -x c - > /dev/null 2>&1 && echo y'), $2)
+
+define BTF_LATEST_SOURCE
+#include <linux/btf.h>
+int main(void) { return BTF_KIND_ENUM64; }
+endef
+
+BTF_OK := $(call test-build,$(BTF_LATEST_SOURCE),y)
+
+ifneq ($(strip $(BTF_OK)), y)
+CFLAGS += -DNO_BTF
+endif
+
LP64 := $(shell echo __LP64__ | ${CC} ${CFLAGS} -E -x c - | tail -n 1)
ifeq ($(LP64), 1)
libdir_relative_temp = lib64
@@ -123,13 +144,6 @@ INCLUDES = -I. -I $(srctree)/include -I $(EP_HEADERS_DIR) $(CONFIG_INCLUDES)

export LIBTRACEEVENT_STATIC LIBTRACEEVENT_SHARED EP_HEADERS_DIR

-# Set compile option CFLAGS
-ifdef EXTRA_CFLAGS
- CFLAGS := $(EXTRA_CFLAGS)
-else
- CFLAGS := -g -Wall
-endif
-
LIBS ?= -ldl
export LIBS

diff --git a/src/meson.build b/src/meson.build
index 3a7a082..2432dd8 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -17,6 +17,18 @@ sources= [
cc = meson.get_compiler('c')
dl_dep = cc.find_library('dl')

+btf_enum64_test_code = '''
+#include <linux/btf.h>
+int main(void) {
+ int x = BTF_KIND_ENUM64;
+ return 0;
+}
+'''
+
+if not cc.compiles(btf_enum64_test_code, name : 'BTF_KIND_ENUM64 check')
+ add_project_arguments('-DNO_BTF', language : 'c')
+endif
+
libtraceevent = library(
'traceevent',
sources,
diff --git a/src/trace-btf.c b/src/trace-btf.c
index 859b086..52e933c 100644
--- a/src/trace-btf.c
+++ b/src/trace-btf.c
@@ -8,12 +8,13 @@
#include <stdlib.h>
#include <stdbool.h>

-#include <linux/btf.h>
-
#include "event-parse.h"
#include "event-utils.h"
#include "event-parse-local.h"

+#ifndef NO_BTF
+#include <linux/btf.h>
+
struct btf_header;
struct btf_type;

@@ -210,17 +211,24 @@ static int load_types(struct tep_btf *btf)
qsort_r(btf->funcs, btf->nr_funcs, sizeof(btf->funcs[0]), cmp_funcs, btf);
return 0;
}
+#endif

__hidden void btf_free(struct tep_btf *btf)
{
+#ifdef NO_BTF
+ tep_warning("BTF not supported.\n");
+ return;
+#else
if (!btf)
return;

free(btf->types);
free(btf->funcs);
free(btf->raw_data);
+#endif
}

+#ifndef NO_BTF
static struct tep_btf *btf_init(void *raw_data, size_t data_size)
{
struct tep_btf *btf;
@@ -271,6 +279,7 @@ static struct tep_btf *btf_init(void *raw_data, size_t data_size)
btf_free(btf);
return NULL;
}
+#endif

/**
* tep_load_btf - Load BTF information into a tep handle
@@ -285,6 +294,10 @@ static struct tep_btf *btf_init(void *raw_data, size_t data_size)
*/
int tep_load_btf(struct tep_handle *tep, void *raw_data, size_t data_size)
{
+#ifdef NO_BTF
+ tep_warning("BTF not supported.\n");
+ return -1;
+#else
/* If btf was already loaded, free it */
btf_free(tep->btf);

@@ -292,8 +305,10 @@ int tep_load_btf(struct tep_handle *tep, void *raw_data, size_t data_size)
if (!tep->btf)
return -1;
return 0;
+#endif
}

+#ifndef NO_BTF
static struct btf_type *btf_get_type(struct tep_btf *btf, int id)
{
if (!id || id > btf->nr_types)
@@ -457,6 +472,7 @@ static int init_btf_func(struct tep_btf *btf, struct trace_seq *s,

return 0;
}
+#endif

/**
* tep_btf_list_args - List the arguments (type and name) for a function
@@ -471,6 +487,10 @@ static int init_btf_func(struct tep_btf *btf, struct trace_seq *s,
*/
int tep_btf_list_args(struct tep_handle *tep, struct trace_seq *s, const char *func)
{
+#ifdef NO_BTF
+ tep_warning("BTF not supported.\n");
+ return -1;
+#else
struct tep_btf *btf = tep->btf;
struct btf_type *type = tep_btf_find_func(btf, func);
struct btf_param *param;
@@ -520,6 +540,7 @@ int tep_btf_list_args(struct tep_handle *tep, struct trace_seq *s, const char *f
trace_seq_printf(s, "%s", param_name);
}
return p;
+#endif
}

/**
@@ -543,6 +564,11 @@ int tep_btf_list_args(struct tep_handle *tep, struct trace_seq *s, const char *f
int tep_btf_print_args(struct tep_handle *tep, struct trace_seq *s, void *args,
int nmem, int size, const char *func)
{
+#ifdef NO_BTF
+ tep_warning("BTF not supported. Args:\n"
+ "args: %08x, nmem: %d, size: %d, func: %08x\n");
+ return -1;
+#else
struct tep_btf *btf = tep->btf;
struct btf_type *type = tep_btf_find_func(btf, func);
struct btf_param *param;
@@ -646,4 +672,5 @@ int tep_btf_print_args(struct tep_handle *tep, struct trace_seq *s, void *args,
}
}
return 0;
+#endif
}
--
2.47.3