[PATCH 5/7] kbuild: remove partial section mismatch detection for built-in.a

From: Masahiro Yamada
Date: Mon Mar 19 2018 - 07:27:27 EST


When built-in.o was incrementally linked with 'ld -r', the section
mismatch analysis for the individual built-in.o was possible when
CONFIG_DEBUG_SECTION_MISMATCH was enabled.

With the migration to the thin archive, built-in.a (former, built-in.o)
is no longer an ELF file. So, the modpost does nothing useful.
scripts/mod/modpost.c just checks the header to bail out, as follows:

/* Is this a valid ELF file? */
if ((hdr->e_ident[EI_MAG0] != ELFMAG0) ||
(hdr->e_ident[EI_MAG1] != ELFMAG1) ||
(hdr->e_ident[EI_MAG2] != ELFMAG2) ||
(hdr->e_ident[EI_MAG3] != ELFMAG3)) {
/* Not an ELF file - silently ignore it */
return 0;
}

We have the full analysis in the final link stage anyway, so we would
not miss the section mismatching.

I do not see a good reason to require extra linking only for the
purpose of the per-directory analysis. Just get rid of this part.

Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
---

scripts/Makefile.build | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 316cb95..66461e9 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -456,8 +456,7 @@ quiet_cmd_link_o_target = AR $@

# If the list of objects to link is empty, just create an empty built-in.a
cmd_link_o_target = $(if $(strip $(real-obj-y)),\
- $(cmd_make_builtin) $@ $(filter $(real-obj-y), $^) \
- $(cmd_secanalysis),\
+ $(cmd_make_builtin) $@ $(filter $(real-obj-y), $^), \
$(cmd_make_empty_builtin) $@)

$(builtin-target): $(real-obj-y) FORCE
--
2.7.4