kbuild: generate modules.builtin

To make it easier for module-init-tools and scripts like mkinitrd to
distinguish builtin and missing modules, install a modules.builtin file
listing all builtin modules. This is done by generating an additional
config file (tristate.conf) with tristate options set to uppercase 'Y'
or 'M'. If we source that config file, the builtin modules appear in
obj-Y.

Signed-off-by: Michal Marek <mmarek@suse.cz>

1 files changed, 55 insertions, 0 deletions

diff --git a/scripts/Makefile.modbuiltin b/scripts/Makefile.modbuiltin
new file mode 100644
index 00000000000..102a276f6ee
--- /dev/null
+++ b/scripts/Makefile.modbuiltin
@@ -0,0 +1,55 @@
+# ==========================================================================
+# Generating modules.builtin
+# ==========================================================================
+
+src := $(obj)
+
+PHONY := __modbuiltin
+__modbuiltin:
+
+-include include/config/auto.conf
+# tristate.conf sets tristate variables to uppercase 'Y' or 'M'
+# That way, we get the list of built-in modules in obj-Y
+-include include/config/tristate.conf
+
+include scripts/Kbuild.include
+
+# The filename Kbuild has precedence over Makefile
+kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
+kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
+include $(kbuild-file)
+
+include scripts/Makefile.lib
+__subdir-Y     := $(patsubst %/,%,$(filter %/, $(obj-Y)))
+subdir-Y       += $(__subdir-Y)
+subdir-ym      := $(sort $(subdir-y) $(subdir-Y) $(subdir-m))
+subdir-ym      := $(addprefix $(obj)/,$(subdir-ym))
+obj-Y          := $(addprefix $(obj)/,$(obj-Y))
+
+modbuiltin-subdirs := $(patsubst %,%/modules.builtin, $(subdir-ym))
+modbuiltin-mods    := $(filter %.ko, $(obj-Y:.o=.ko))
+modbuiltin-target  := $(obj)/modules.builtin
+
+__modbuiltin: $(modbuiltin-target) $(subdir-ym)
+        @:
+
+$(modbuiltin-target): $(subdir-ym) FORCE
+        $(Q)(for m in $(modbuiltin-mods); do echo kernel/$$m; done;     \
+        cat /dev/null $(modbuiltin-subdirs)) > $@
+
+PHONY += FORCE
+
+FORCE:
+
+# Descending
+# ---------------------------------------------------------------------------
+
+PHONY += $(subdir-ym)
+$(subdir-ym):
+        $(Q)$(MAKE) $(modbuiltin)=$@
+
+
+# Declare the contents of the .PHONY variable as phony.  We keep that
+# information in a variable se we can use it in if_changed and friends.
+
+.PHONY: $(PHONY)