From: Leo Yan <leo.yan@arm.com>
Date: Tue, 2 Jun 2026 14:47:17 +0000 (+0100)
Subject: selftests/bpf: Avoid static LLVM linking for cross builds
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=62617d28d9ae123c0d6ba51035caa3ca52b94f7a;p=thirdparty%2Fkernel%2Flinux.git

selftests/bpf: Avoid static LLVM linking for cross builds

The BPF selftests prefer static LLVM linking, which works for native
builds but can break cross builds. Its --link-static output may include
host-only libraries that are unavailable for the cross compilation,
causing link failures.

Avoid static LLVM linking for cross builds and use shared LLVM libraries
instead. Native builds keep the existing behavior.

Signed-off-by: Leo Yan <leo.yan@arm.com>
Link: https://lore.kernel.org/r/20260602-tools_build_fix_zero_init_bpf_only-v2-8-c76e5250ea1c@arm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 302a8aed3bf99..b642ee489ea64 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -194,8 +194,15 @@ ifeq ($(feature-llvm),1)
   LLVM_CONFIG_LIB_COMPONENTS := mcdisassembler all-targets
   # both llvm-config and lib.mk add -D_GNU_SOURCE, which ends up as conflict
   LLVM_CFLAGS  += $(filter-out -D_GNU_SOURCE,$(shell $(LLVM_CONFIG) --cflags))
-  # Prefer linking statically if it's available, otherwise fallback to shared
-  ifeq ($(shell $(LLVM_CONFIG) --link-static --libs >/dev/null 2>&1 && echo static),static)
+  # Cross compilation must use dynamic linking to avoid unresolved library
+  # dependencies. For native build, prefer linking statically if it's
+  # available, otherwise fallback to shared.
+  ifneq ($(ARCH), $(HOSTARCH))
+    LLVM_LINK_STATIC :=
+  else
+    LLVM_LINK_STATIC := $(shell $(LLVM_CONFIG) --link-static --libs >/dev/null 2>&1 && echo y)
+  endif
+  ifeq ($(LLVM_LINK_STATIC),y)
     LLVM_LDLIBS  += $(shell $(LLVM_CONFIG) --link-static --libs $(LLVM_CONFIG_LIB_COMPONENTS))
     LLVM_LDLIBS  += $(filter-out -lxml2,$(shell $(LLVM_CONFIG) --link-static --system-libs $(LLVM_CONFIG_LIB_COMPONENTS)))
     LLVM_LDLIBS  += -lstdc++