When the check_undefined command in kernel/trace/Makefile fails, there
is no output, making it hard to understand why the build failed. Capture
the output of the $(NM) + grep command and print it when failing to make
it clearer what the problem is.
Fixes: a717943d8ecc ("tracing: Check for undefined symbols in
simple_ring_buffer")
Signed-off-by: Nathan Chancellor <[email protected]>
---
Commit a717943d8ecc ("tracing: Check for undefined symbols in
simple_ring_buffer") and its follow up fixes are in the kvmarm tree so
this should go there as well. This is the rebased version of my
suggestion in the original thread:
https://lore.kernel.org/20260311221816.GA316631@ax162/
---
kernel/trace/Makefile | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index c5e14ffd36ee..d662c1a64cd5 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -174,7 +174,13 @@ UNDEFINED_ALLOWLIST = __asan __gcov __kasan __kcsan
__hwasan __sancov __sanitize
$(shell $(NM) -u $(obj)/undefsyms_base.o 2>/dev/null |
awk '{print $$2}')
quiet_cmd_check_undefined = NM $<
- cmd_check_undefined = test -z "`$(NM) -u $< | grep -v $(addprefix -e ,
$(UNDEFINED_ALLOWLIST))`"
+ cmd_check_undefined = \
+ undefsyms=$$($(NM) -u $< | grep -v $(addprefix -e ,
$(UNDEFINED_ALLOWLIST)) || true); \
+ if [ -n "$$undefsyms" ]; then \
+ echo "Unexpected symbols in $<:" >&2; \
+ echo "$$undefsyms" >&2; \
+ false; \
+ fi
$(obj)/%.o.checked: $(obj)/%.o $(obj)/undefsyms_base.o FORCE
$(call if_changed,check_undefined)
---
base-commit: e3d585ed3ff891a00c2284fef4be9cf8581735ab
change-id: 20260320-cmd_check_undefined-verbose-7d15f13f615d
Best regards,
--
Nathan Chancellor <[email protected]>
