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 <[e-mail]>
Tested-by: Paul E. McKenney <[e-mail]>
Cc: Michal Marek <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/kbuild/kconfig-language.txt

···
     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
 -----------------
 

init/Kconfig

···
 
 config EMBEDDED
 	bool "Embedded system"
+	option allnoconfig_y
 	select EXPERT
 	help
 	  This option should be enabled if compiling the kernel for

scripts/kconfig/confdata.c

···
 				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;

scripts/kconfig/expr.h

···
 /* 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
 

scripts/kconfig/lkc.h

···
 #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;

scripts/kconfig/menu.c

···
 	case T_OPT_ENV:
 		prop_add_env(arg);
 		break;
+	case T_OPT_ALLNOCONFIG_Y:
+		current_entry->sym->flags |= SYMBOL_ALLNOCONFIG_Y;
+		break;
 	}
 }
 

scripts/kconfig/zconf.gperf

···
 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
 %%

scripts/kconfig/zconf.hash.c_shipped

···
       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,
···
     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")];
···
     "mainmenu",
     "menuconfig",
     "modules",
+    "allnoconfig_y",
     "menu",
     "select",
     "comment",
···
 {
   enum
     {
-      TOTAL_KEYWORDS = 32,
+      TOTAL_KEYWORDS = 33,
       MIN_WORD_LENGTH = 2,
       MAX_WORD_LENGTH = 14,
       MIN_HASH_VALUE = 2,
···
       {-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},
···
     }
   return 0;
 }
-#line 47 "scripts/kconfig/zconf.gperf"
+#line 48 "scripts/kconfig/zconf.gperf"