By having a BTF_BASE variable defaulting to using vmlinux
as base BTF, we allow module builders to build standalone
BTF such that it is generated independently and not
de-duplicated with core vmlinux BTF. This allows such
modules to be more resilient to changes in vmlinux BTF
if they occur, as would happen if a change resulted in
a different vmlinux BTF id mapping.
Opt-out of split BTF is done via
make BTF_BASE= M=path/2/module
Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
---
scripts/Makefile.modfinal | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index 25bedd8..7294918 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -30,6 +30,8 @@ quiet_cmd_cc_o_c = CC [M] $@
ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
+BTF_BASE := --btf_base vmlinux
+
quiet_cmd_ld_ko_o = LD [M] $@
cmd_ld_ko_o += \
$(LD) -r $(KBUILD_LDFLAGS) \
@@ -44,7 +46,7 @@ quiet_cmd_btf_ko = BTF [M] $@
elif [ -n "$(CONFIG_RUST)" ] && $(srctree)/scripts/is_rust_module.sh $@; then \
printf "Skipping BTF generation for %s because it's a Rust module\n" $@ 1>&2; \
else \
- LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) --btf_base vmlinux $@; \
+ LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) $(BTF_BASE) $@; \
$(RESOLVE_BTFIDS) -b vmlinux $@; \
fi;
--
1.8.3.1
