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>

.gitignore

@@ -22,6 +22,7 @@
 *.lst
 *.symtypes
 *.order
+modules.builtin
 *.elf
 *.bin
 *.gz

Documentation/kbuild/kbuild.txt

@@ -1,3 +1,17 @@
+Output files
+
+modules.order
+--------------------------------------------------
+This file records the order in which modules appear in Makefiles. This
+is used by modprobe to deterministically resolve aliases that match
+multiple modules.
+
+modules.builtin
+--------------------------------------------------
+This file lists all modules that are built into the kernel. This is used
+by modprobe to not fail when trying to load something builtin.
+
+
 Environment variables
 
 KCPPFLAGS

Documentation/kbuild/kconfig.txt

@@ -103,6 +103,11 @@ KCONFIG_AUTOCONFIG
 This environment variable can be set to specify the path & name of the
 "auto.conf" file.  Its default value is "include/config/auto.conf".
 
+KCONFIG_TRISTATE
+--------------------------------------------------
+This environment variable can be set to specify the path & name of the
+"tristate.conf" file.  Its default value is "include/config/tristate.conf".
+
 KCONFIG_AUTOHEADER
 --------------------------------------------------
 This environment variable can be set to specify the path & name of the

Makefile

@@ -464,7 +464,7 @@ ifeq ($(KBUILD_EXTMOD),)
 # Carefully list dependencies so we do not try to build scripts twice
 # in parallel
 PHONY += scripts
-scripts: scripts_basic include/config/auto.conf
+scripts: scripts_basic include/config/auto.conf include/config/tristate.conf
 	$(Q)$(MAKE) $(build)=$(@)
 
 # Objects we will link into vmlinux / subdirs we need to visit
@@ -491,7 +491,7 @@ $(KCONFIG_CONFIG) include/config/auto.conf.cmd: ;
 # with it and forgot to run make oldconfig.
 # if auto.conf.cmd is missing then we are probably in a cleaned tree so
 # we execute the config step to be sure to catch updated Kconfig files
-include/config/auto.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
+include/config/%.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
 	$(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
 else
 # external modules needs include/generated/autoconf.h and include/config/auto.conf
@@ -876,6 +876,9 @@ $(sort $(vmlinux-init) $(vmlinux-main)) $(vmlinux-lds): $(vmlinux-dirs) ;
 PHONY += $(vmlinux-dirs)
 $(vmlinux-dirs): prepare scripts
 	$(Q)$(MAKE) $(build)=$@
+ifdef CONFIG_MODULES
+	$(Q)$(MAKE) $(modbuiltin)=$@
+endif
 
 # Build the kernel release string
 #
@@ -1080,6 +1083,7 @@ all: modules
 PHONY += modules
 modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux)
 	$(Q)$(AWK) '!x[$$0]++' $(vmlinux-dirs:%=$(objtree)/%/modules.order) > $(objtree)/modules.order
+	$(Q)$(AWK) '!x[$$0]++' $(vmlinux-dirs:%=$(objtree)/%/modules.builtin) > $(objtree)/modules.builtin
 	@$(kecho) '  Building modules, stage 2.';
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_modbuild
@@ -1109,6 +1113,7 @@ _modinst_:
 		ln -s $(objtree) $(MODLIB)/build ; \
 	fi
 	@cp -f $(objtree)/modules.order $(MODLIB)/
+	@cp -f $(objtree)/modules.builtin $(MODLIB)/
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst
 
 # This depmod is only for convenience to give the initial
@@ -1169,7 +1174,7 @@ clean: archclean $(clean-dirs)
 		\( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \
 		-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
 		-o -name '*.symtypes' -o -name 'modules.order' \
-		-o -name '.tmp_*.o.*' \
+		-o modules.order -o -name '.tmp_*.o.*' \
 		-o -name '*.gcno' \) -type f -print | xargs rm -f
 
 # mrproper - Delete all generated files, including .config
@@ -1367,7 +1372,8 @@ $(clean-dirs):
 
 clean:	rm-dirs := $(MODVERDIR)
 clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers \
-                   $(KBUILD_EXTMOD)/modules.order
+                   $(KBUILD_EXTMOD)/modules.order \
+                   $(KBUILD_EXTMOD)/modules.builtin
 clean: $(clean-dirs)
 	$(call cmd,rmdirs)
 	$(call cmd,rmfiles)

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)), \

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)

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;
 			}
@@ -772,13 +786,19 @@ int conf_write_autoconf(void)
 		}
 	}
 	fclose(out);
+	fclose(tristate);
 	fclose(out_h);
 
 	name = getenv("KCONFIG_AUTOHEADER");
 	if (!name)
 		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