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kbuild: fix building bzImage with CONFIG_TRIM_UNUSED_KSYMS enabled

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When building a specific target such as bzImage, modules aren't normally
built.  However if CONFIG_TRIM_UNUSED_KSYMS is enabled, no built modules
means none of the exported symbols are used and therefore they will all
be trimmed away from the final kernel.  A subsequent "make modules" will
fail because modpost cannot find the needed symbols for those modules in
the kernel binary.

Let's make sure modules are also built whenever CONFIG_TRIM_UNUSED_KSYMS
is enabled and that the kernel binary is properly rebuilt accordingly.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nicolas Pitre 2016-12-02 15:11:50 -05:00 committed by Linus Torvalds
parent 8dc0f265d3
commit 8655639240
1 changed files with 8 additions and 1 deletions
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9
Makefile
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@ -607,6 +607,13 @@ else
include/config/auto.conf: ;
endif # $(dot-config)
# For the kernel to actually contain only the needed exported symbols,
# we have to build modules as well to determine what those symbols are.
# (this can be evaluated only once include/config/auto.conf has been included)
ifdef CONFIG_TRIM_UNUSED_KSYMS
KBUILD_MODULES := 1
endif
# The all: target is the default when no target is given on the
# command line.
# This allow a user to issue only 'make' to build a kernel including modules
@ -944,7 +951,7 @@ ifdef CONFIG_GDB_SCRIPTS
endif
ifdef CONFIG_TRIM_UNUSED_KSYMS
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh \
"$(MAKE) KBUILD_MODULES=1 -f $(srctree)/Makefile vmlinux_prereq"
"$(MAKE) -f $(srctree)/Makefile vmlinux"
endif
# standalone target for easier testing