kconfig: fix .config dependencies

This fixes one of the worst kbuild warts left - the broken dependencies used
to check and regenerate the .config file.  This was done via an indirect
dependency and the .config itself had an empty command, which can cause make
not to reread the changed .config file.

Instead of this we generate now a new file include/config/auto.conf from
.config, which is used for kbuild and has the proper dependencies.  It's also
the main make target now for all files generated during this step (and thus
replaces include/linux/autoconf.h).

This also means we can now relax the syntax requirements for the .config file
and we don't have to rewrite it all the time, i.e.  silentoldconfig only
writes .config now when it's necessary to keep it in sync with the Kconfig
files and even this can be suppressed by setting the environment variable
KCONFIG_NOSILENTUPDATE, so the update can (and must) be done manually.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

6 files changed, 145 insertions, 57 deletions

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index e48e60da3040..53e53a2e80ae 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -8,7 +8,7 @@ PHONY := __build
 __build:
 
 # Read .config if it exist, otherwise ignore
--include .config
+-include include/config/auto.conf
 
 include scripts/Kbuild.include
 
diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index 0e056cffffdb..576cce5e387f 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -35,7 +35,7 @@
 PHONY := _modpost
 _modpost: __modpost
 
-include .config
+include include/config/auto.conf
 include scripts/Kbuild.include
 include scripts/Makefile.lib
 
diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
index 8012d1076876..9334da65f364 100644
--- a/scripts/kconfig/conf.c
+++ b/scripts/kconfig/conf.c
@@ -599,7 +599,15 @@ int main(int ac, char **av)
                         input_mode = ask_silent;
                         valid_stdin = 1;
                 }
-        }
+        } else if (sym_change_count) {
+                name = getenv("KCONFIG_NOSILENTUPDATE");
+                if (name && *name) {
+                        fprintf(stderr, _("\n*** Kernel configuration requires explicit update.\n\n"));
+                        return 1;
+                }
+        } else
+                goto skip_check;
+
         do {
                 conf_cnt = 0;
                 check_conf(&rootmenu);
@@ -608,5 +616,11 @@ int main(int ac, char **av)
                 fprintf(stderr, _("\n*** Error during writing of the kernel configuration.\n\n"));
                 return 1;
         }
+skip_check:
+        if (input_mode == ask_silent && conf_write_autoconf()) {
+                fprintf(stderr, _("\n*** Error during writing of the kernel configuration.\n\n"));
+                return 1;
+        }
+
         return 0;
 }
diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index a9e3b6abf661..2da4a8d775a5 100644
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -342,7 +342,7 @@ int conf_read(const char *name)
 
 int conf_write(const char *name)
 {
-        FILE *out, *out_h;
+        FILE *out;
         struct symbol *sym;
         struct menu *menu;
         const char *basename;
@@ -379,13 +379,6 @@ int conf_write(const char *name)
         out = fopen(newname, "w");
         if (!out)
                 return 1;
-        out_h = NULL;
-        if (!name) {
-                out_h = fopen(".tmpconfig.h", "w");
-                if (!out_h)
-                        return 1;
-                file_write_dep(NULL);
-        }
         sym = sym_lookup("KERNELVERSION", 0);
         sym_calc_value(sym);
         time(&now);
@@ -401,16 +394,6 @@ int conf_write(const char *name)
                      sym_get_string_value(sym),
                      use_timestamp ? "# " : "",
                      use_timestamp ? ctime(&now) : "");
-        if (out_h)
-                fprintf(out_h, "/*\n"
-                               " * Automatically generated C config: don't edit\n"
-                               " * Linux kernel version: %s\n"
-                               "%s%s"
-                               " */\n"
-                               "#define AUTOCONF_INCLUDED\n",
-                               sym_get_string_value(sym),
-                               use_timestamp ? " * " : "",
-                               use_timestamp ? ctime(&now) : "");
 
         if (!sym_change_count)
                 sym_clear_all_valid();
@@ -426,11 +409,6 @@ int conf_write(const char *name)
                                      "#\n"
                                      "# %s\n"
                                      "#\n", str);
-                        if (out_h)
-                                fprintf(out_h, "\n"
-                                               "/*\n"
-                                               " * %s\n"
-                                               " */\n", str);
                 } else if (!(sym->flags & SYMBOL_CHOICE)) {
                         sym_calc_value(sym);
                         if (!(sym->flags & SYMBOL_WRITE))
@@ -448,59 +426,39 @@ int conf_write(const char *name)
                                 switch (sym_get_tristate_value(sym)) {
                                 case no:
                                         fprintf(out, "# CONFIG_%s is not set\n", sym->name);
-                                        if (out_h)
-                                                fprintf(out_h, "#undef CONFIG_%s\n", sym->name);
                                         break;
                                 case mod:
                                         fprintf(out, "CONFIG_%s=m\n", sym->name);
-                                        if (out_h)
-                                                fprintf(out_h, "#define CONFIG_%s_MODULE 1\n", sym->name);
                                         break;
                                 case yes:
                                         fprintf(out, "CONFIG_%s=y\n", sym->name);
-                                        if (out_h)
-                                                fprintf(out_h, "#define CONFIG_%s 1\n", sym->name);
                                         break;
                                 }
                                 break;
                         case S_STRING:
-                                // fix me
                                 str = sym_get_string_value(sym);
                                 fprintf(out, "CONFIG_%s=\"", sym->name);
-                                if (out_h)
-                                        fprintf(out_h, "#define CONFIG_%s \"", sym->name);
-                                do {
+                                while (1) {
                                         l = strcspn(str, "\"\\");
                                         if (l) {
                                                 fwrite(str, l, 1, out);
-                                                if (out_h)
-                                                        fwrite(str, l, 1, out_h);
-                                        }
-                                        str += l;
-                                        while (*str == '\\' || *str == '"') {
-                                                fprintf(out, "\\%c", *str);
-                                                if (out_h)
-                                                        fprintf(out_h, "\\%c", *str);
-                                                str++;
+                                                str += l;