kconfig: make allnoconfig disable options behind EMBEDDED and EXPERT

"make allnoconfig" exists to ease testing of minimal configurations.
Documentation/SubmitChecklist includes a note to test with allnoconfig.
This helps catch missing dependencies on common-but-not-required
functionality, which might otherwise go unnoticed.

However, allnoconfig still leaves many symbols enabled, because they're
hidden behind CONFIG_EMBEDDED or CONFIG_EXPERT.  For instance, allnoconfig
still has CONFIG_PRINTK and CONFIG_BLOCK enabled, so drivers don't
typically get build-tested with those disabled.

To address this, introduce a new Kconfig option "allnoconfig_y", used on
symbols which only exist to hide other symbols.  Set it on CONFIG_EMBEDDED
(which then selects CONFIG_EXPERT).  allnoconfig will then disable all the
symbols hidden behind those.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

8 files changed, 25 insertions, 6 deletions

diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt
index c420676c6fe31d..350f733bf2c716 100644
--- a/Documentation/kbuild/kconfig-language.txt
+++ b/Documentation/kbuild/kconfig-language.txt
@@ -157,6 +157,10 @@ applicable everywhere (see syntax).
     to the build environment (if this is desired, it can be done via
     another symbol).
 
+  - "allnoconfig_y"
+    This declares the symbol as one that should have the value y when
+    using "allnoconfig". Used for symbols that hide other symbols.
+
 Menu dependencies
 -----------------
 
diff --git a/init/Kconfig b/init/Kconfig
index 8851c64178801b..427ba60d638fce 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1483,6 +1483,7 @@ config PCI_QUIRKS
 
 config EMBEDDED
 	bool "Embedded system"
+	option allnoconfig_y
 	select EXPERT
 	help
 	  This option should be enabled if compiling the kernel for
diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index 87f723804079ed..f88d90f20228e8 100644
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -1178,7 +1178,10 @@ bool conf_set_all_new_symbols(enum conf_def_mode mode)
 				sym->def[S_DEF_USER].tri = mod;
 				break;
 			case def_no:
-				sym->def[S_DEF_USER].tri = no;
+				if (sym->flags & SYMBOL_ALLNOCONFIG_Y)
+					sym->def[S_DEF_USER].tri = yes;
+				else
+					sym->def[S_DEF_USER].tri = no;
 				break;
 			case def_random:
 				sym->def[S_DEF_USER].tri = no;
diff --git a/scripts/kconfig/expr.h b/scripts/kconfig/expr.h
index ba663e1dc7e35b..412ea8a2abb8b8 100644
--- a/scripts/kconfig/expr.h
+++ b/scripts/kconfig/expr.h
@@ -109,6 +109,9 @@ struct symbol {
 /* choice values need to be set before calculating this symbol value */
 #define SYMBOL_NEED_SET_CHOICE_VALUES  0x100000
 
+/* Set symbol to y if allnoconfig; used for symbols that hide others */
+#define SYMBOL_ALLNOCONFIG_Y 0x200000
+
 #define SYMBOL_MAXLENGTH	256
 #define SYMBOL_HASHSIZE		9973
 
diff --git a/scripts/kconfig/lkc.h b/scripts/kconfig/lkc.h
index 09f4edfdc91132..d5daa7af8b496e 100644
--- a/scripts/kconfig/lkc.h
+++ b/scripts/kconfig/lkc.h
@@ -61,6 +61,7 @@ enum conf_def_mode {
 #define T_OPT_MODULES		1
 #define T_OPT_DEFCONFIG_LIST	2
 #define T_OPT_ENV		3
+#define T_OPT_ALLNOCONFIG_Y	4
 
 struct kconf_id {
 	int name;
diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index db1512ae30cc48..3ac2c9c6e28030 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -217,6 +217,9 @@ void menu_add_option(int token, char *arg)
 	case T_OPT_ENV:
 		prop_add_env(arg);
 		break;
+	case T_OPT_ALLNOCONFIG_Y:
+		current_entry->sym->flags |= SYMBOL_ALLNOCONFIG_Y;
+		break;
 	}
 }
 
diff --git a/scripts/kconfig/zconf.gperf b/scripts/kconfig/zconf.gperf
index f14ab41154b665..b6ac02d604f1fb 100644
--- a/scripts/kconfig/zconf.gperf
+++ b/scripts/kconfig/zconf.gperf
@@ -44,4 +44,5 @@ on,		T_ON,		TF_PARAM
 modules,	T_OPT_MODULES,	TF_OPTION
 defconfig_list,	T_OPT_DEFCONFIG_LIST,TF_OPTION
 env,		T_OPT_ENV,	TF_OPTION
+allnoconfig_y,	T_OPT_ALLNOCONFIG_Y,TF_OPTION
 %%
diff --git a/scripts/kconfig/zconf.hash.c_shipped b/scripts/kconfig/zconf.hash.c_shipped
index 40df0005daa928..c77a8eff1ef21e 100644
--- a/scripts/kconfig/zconf.hash.c_shipped
+++ b/scripts/kconfig/zconf.hash.c_shipped
@@ -55,10 +55,10 @@ kconf_id_hash (register const char *str, register unsigned int len)
       73, 73, 73, 73, 73, 73, 73, 73, 73, 73,
       73, 73, 73, 73, 73, 73, 73, 73, 73, 73,
       73, 73, 73, 73, 73, 73, 73, 73, 73, 73,
-      73, 73, 73, 73, 73, 73, 73, 73, 25, 25,
+      73, 73, 73, 73, 73, 73, 73,  5, 25, 25,
        0,  0,  0,  5,  0,  0, 73, 73,  5,  0,
       10,  5, 45, 73, 20, 20,  0, 15, 15, 73,
-      20, 73, 73, 73, 73, 73, 73, 73, 73, 73,
+      20,  5, 73, 73, 73, 73, 73, 73, 73, 73,
       73, 73, 73, 73, 73, 73, 73, 73, 73, 73,
       73, 73, 73, 73, 73, 73, 73, 73, 73, 73,
       73, 73, 73, 73, 73, 73, 73, 73, 73, 73,
@@ -106,6 +106,7 @@ struct kconf_id_strings_t
     char kconf_id_strings_str23[sizeof("mainmenu")];
     char kconf_id_strings_str25[sizeof("menuconfig")];
     char kconf_id_strings_str27[sizeof("modules")];
+    char kconf_id_strings_str28[sizeof("allnoconfig_y")];
     char kconf_id_strings_str29[sizeof("menu")];
     char kconf_id_strings_str31[sizeof("select")];
     char kconf_id_strings_str32[sizeof("comment")];
@@ -141,6 +142,7 @@ static const struct kconf_id_strings_t kconf_id_strings_contents =
     "mainmenu",
     "menuconfig",
     "modules",
+    "allnoconfig_y",
     "menu",
     "select",
     "comment",
@@ -170,7 +172,7 @@ kconf_id_lookup (register const char *str, register unsigned int len)
 {
   enum
     {
-      TOTAL_KEYWORDS = 32,
+      TOTAL_KEYWORDS = 33,
       MIN_WORD_LENGTH = 2,
       MAX_WORD_LENGTH = 14,
       MIN_HASH_VALUE = 2,
@@ -219,7 +221,8 @@ kconf_id_lookup (register const char *str, register unsigned int len)
       {-1},
 #line 44 "scripts/kconfig/zconf.gperf"
       {(int)(long)&((struct kconf_id_strings_t *)0)->kconf_id_strings_str27,	T_OPT_MODULES,	TF_OPTION},
-      {-1},
+#line 47 "scripts/kconfig/zconf.gperf"
+      {(int)(long)&((struct kconf_id_strings_t *)0)->kconf_id_strings_str28,	T_OPT_ALLNOCONFIG_Y,TF_OPTION},
 #line 16 "scripts/kconfig/zconf.gperf"
       {(int)(long)&((struct kconf_id_strings_t *)0)->kconf_id_strings_str29,		T_MENU,		TF_COMMAND},
       {-1},
@@ -282,5 +285,5 @@ kconf_id_lookup (register const char *str, register unsigned int len)
     }
   return 0;
 }
-#line 47 "scripts/kconfig/zconf.gperf"
+#line 48 "scripts/kconfig/zconf.gperf"