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>

3 files changed, 82 insertions, 1 deletions

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index c67e73ecd5b..ed2773edfe7 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -149,6 +149,12 @@ ld-option = $(call try-run,\
 # $(Q)$(MAKE) $(build)=dir
 build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
 
+###
+# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.modbuiltin obj=
+# Usage:
+# $(Q)$(MAKE) $(modbuiltin)=dir
+modbuiltin := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.modbuiltin obj
+
 # Prefix -I with $(srctree) if it is not an absolute path.
 # skip if -I has no parameter
 addtree = $(if $(patsubst -I%,%,$(1)), \
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)
diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index 797a7410f69..c4dec80cfd8 100644
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -677,7 +677,7 @@ int conf_write_autoconf(void)
 	struct symbol *sym;
 	const char *str;
 	const char *name;
-	FILE *out, *out_h;
+	FILE *out, *tristate, *out_h;
 	time_t now;
 	int i, l;
 
@@ -692,9 +692,16 @@ int conf_write_autoconf(void)
 	if (!out)
 		return 1;
 
+	tristate = fopen(".tmpconfig_tristate", "w");
+	if (!tristate) {
+		fclose(out);
+		return 1;
+	}
+
 	out_h = fopen(".tmpconfig.h", "w");
 	if (!out_h) {
 		fclose(out);
+		fclose(tristate);
 		return 1;
 	}
 
@@ -707,6 +714,9 @@ int conf_write_autoconf(void)
 		     "# %s"
 		     "#\n",
 		     sym_get_string_value(sym), ctime(&now));
+	fprintf(tristate, "#\n"
+			  "# Automatically generated - do not edit\n"
+			  "\n");
 	fprintf(out_h, "/*\n"
 		       " * Automatically generated C config: don't edit\n"
 		       " * Linux kernel version: %s\n"
@@ -727,10 +737,14 @@ int conf_write_autoconf(void)
 				break;
 			case mod:
 				fprintf(out, "CONFIG_%s=m\n", sym->name);
+				fprintf(tristate, "CONFIG_%s=M\n", sym->name);
 				fprintf(out_h, "#define CONFIG_%s_MODULE 1\n", sym->name);
 				break;
 			case yes:
 				fprintf(out, "CONFIG_%s=y\n", sym->name);
+				if (sym->type == S_TRISTATE)
+					fprintf(tristate, "CONFIG_%s=Y\n",
+							sym->name);
 				fprintf(out_h, "#define CONFIG_%s 1\n", sym->name);
 				break;
 			}
@@ -772,6 +786,7 @@ int conf_write_autoconf(void)
 		}
 	}
 	fclose(out);
+	fclose(tristate);
 	fclose(out_h);
 
 	name = getenv("KCONFIG_AUTOHEADER");
@@ -779,6 +794,11 @@ int conf_write_autoconf(void)
 		name = "include/generated/autoconf.h";
 	if (rename(".tmpconfig.h", name))
 		return 1;
+	name = getenv("KCONFIG_TRISTATE");
+	if (!name)
+		name = "include/config/tristate.conf";
+	if (rename(".tmpconfig_tristate", name))
+		return 1;
 	name = conf_get_autoconfig_name();
 	/*
 	 * This must be the last step, kbuild has a dependency on auto.conf