Add a recent kconfig version to coreinfo, in order to make the

supported features configurable later (currently unused). Store all
build files and results (coreinfo.elf) in build/ now.

I'm self-acking this as (though non-"trivial") it doesn't affect coreinfo
in its functionality, this is more or less a "cosmetic" change to the
build interface ("make" -> "make menuconfig && make").

This is a kconfig checkout from the Linux kernel (where kconfig is being
actively maintained) from 03/2008. The hash identifying the last commit
to kconfig is 587c90616a5b44e6ccfac38e64d4fecee51d588c.

The amount of changes to kconfig itself has been kept as small as possible
to keep the diff small and to ease updating/porting to newer kconfig versions.
The following changes were performed on the upstream Linux kconfig:

 - s/kernel/coreinfo/, and s/Linux/coreinfo/ in various strings.

 - Consistently use the env. variable KERNELVERSION in all kconfig
   interfaces -- e.g. config/menuconfig/gconfig/xconfig -- as version number.

 - Hardcode our paths/filenames in some places (could be improved upstream).

 - Always write .config and build/config.h, no matter which kconfig
   interface is used (config/menuconfig/gconfig/xconfig). We want to
   include build/config.h in our code.

 - Adapt the kconfig Makefile for our purposes (build/ directory, rules, etc).

In addition, a few items in the coreinfo Makefile are needed for this to work.

This kconfig setup is successfully tested with all targets from 'make help':

  config          - Update current config utilising a line-oriented program
  menuconfig      - Update current config utilising a menu based program
  xconfig         - Update current config utilising a QT based front-end
  gconfig         - Update current config utilising a GTK based front-end
  oldconfig       - Update current config utilising a provided .config as base
  silentoldconfig - Same as oldconfig, but quietly
  randconfig      - New config with random answer to all options
  defconfig       - New config with default answer to all options
  allmodconfig    - New config selecting modules when possible
  allyesconfig    - New config where all options are accepted with yes
  allnoconfig     - New config where all options are answered with no

For 'make defconfig' to work you have to do (which we don't need in coreinfo):

  $ mkdir configs; touch configs/defconfig

You can also use 'make foo_defconfig' in which case kconfig will use a
file called 'configs/foo_defconfig' as basis.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>



git-svn-id: svn://svn.coreboot.org/coreboot/trunk@3188 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

1 files changed, 917 insertions, 0 deletions

diff --git a/payloads/coreinfo/util/kconfig/symbol.c b/payloads/coreinfo/util/kconfig/symbol.c
new file mode 100644
index 0000000000..4a03191ad1
--- /dev/null
+++ b/payloads/coreinfo/util/kconfig/symbol.c
@@ -0,0 +1,917 @@
+/*
+ * Copyright (C) 2002 Roman Zippel <zippel@linux-m68k.org>
+ * Released under the terms of the GNU GPL v2.0.
+ */
+
+#include <ctype.h>
+#include <stdlib.h>
+#include <string.h>
+#include <regex.h>
+#include <sys/utsname.h>
+
+#define LKC_DIRECT_LINK
+#include "lkc.h"
+
+struct symbol symbol_yes = {
+	.name = "y",
+	.curr = { "y", yes },
+	.flags = SYMBOL_CONST|SYMBOL_VALID,
+}, symbol_mod = {
+	.name = "m",
+	.curr = { "m", mod },
+	.flags = SYMBOL_CONST|SYMBOL_VALID,
+}, symbol_no = {
+	.name = "n",
+	.curr = { "n", no },
+	.flags = SYMBOL_CONST|SYMBOL_VALID,
+}, symbol_empty = {
+	.name = "",
+	.curr = { "", no },
+	.flags = SYMBOL_VALID,
+};
+
+struct symbol *sym_defconfig_list;
+struct symbol *modules_sym;
+tristate modules_val;
+
+struct expr *sym_env_list;
+
+void sym_add_default(struct symbol *sym, const char *def)
+{
+	struct property *prop = prop_alloc(P_DEFAULT, sym);
+
+	prop->expr = expr_alloc_symbol(sym_lookup(def, 1));
+}
+
+void sym_init(void)
+{
+	struct symbol *sym;
+	struct utsname uts;
+	static bool inited = false;
+
+	if (inited)
+		return;
+	inited = true;
+
+	uname(&uts);
+
+	sym = sym_lookup("UNAME_RELEASE", 0);
+	sym->type = S_STRING;
+	sym->flags |= SYMBOL_AUTO;
+	sym_add_default(sym, uts.release);
+}
+
+enum symbol_type sym_get_type(struct symbol *sym)
+{
+	enum symbol_type type = sym->type;
+
+	if (type == S_TRISTATE) {
+		if (sym_is_choice_value(sym) && sym->visible == yes)
+			type = S_BOOLEAN;
+		else if (modules_val == no)
+			type = S_BOOLEAN;
+	}
+	return type;
+}
+
+const char *sym_type_name(enum symbol_type type)
+{
+	switch (type) {
+	case S_BOOLEAN:
+		return "boolean";
+	case S_TRISTATE:
+		return "tristate";
+	case S_INT:
+		return "integer";
+	case S_HEX:
+		return "hex";
+	case S_STRING:
+		return "string";
+	case S_UNKNOWN:
+		return "unknown";
+	case S_OTHER:
+		break;
+	}
+	return "???";
+}
+
+struct property *sym_get_choice_prop(struct symbol *sym)
+{
+	struct property *prop;
+
+	for_all_choices(sym, prop)
+		return prop;
+	return NULL;
+}
+
+struct property *sym_get_env_prop(struct symbol *sym)
+{
+	struct property *prop;
+
+	for_all_properties(sym, prop, P_ENV)
+		return prop;
+	return NULL;
+}
+
+struct property *sym_get_default_prop(struct symbol *sym)
+{
+	struct property *prop;
+
+	for_all_defaults(sym, prop) {
+		prop->visible.tri = expr_calc_value(prop->visible.expr);
+		if (prop->visible.tri != no)
+			return prop;
+	}
+	return NULL;
+}
+
+struct property *sym_get_range_prop(struct symbol *sym)
+{
+	struct property *prop;
+
+	for_all_properties(sym, prop, P_RANGE) {
+		prop->visible.tri = expr_calc_value(prop->visible.expr);
+		if (prop->visible.tri != no)
+			return prop;
+	}
+	return NULL;
+}
+
+static int sym_get_range_val(struct symbol *sym, int base)
+{
+	sym_calc_value(sym);
+	switch (sym->type) {
+	case S_INT:
+		base = 10;
+		break;
+	case S_HEX:
+		base = 16;
+		break;
+	default:
+		break;
+	}
+	return strtol(sym->curr.val, NULL, base);
+}
+
+static void sym_validate_range(struct symbol *sym)
+{
+	struct property *prop;
+	int base, val, val2;
+	char str[64];
+
+	switch (sym->type) {
+	case S_INT:
+		base = 10;
+		break;
+	case S_HEX:
+		base = 16;
+		break;
+	default:
+		return;
+	}
+	prop = sym_get_range_prop(sym);
+	if (!prop)
+		return;
+	val = strtol(sym->curr.val, NULL, base);
+	val2 = sym_get_range_val(prop->expr->left.sym, base);
+	if (val >= val2) {
+		val2 = sym_get_range_val(prop->expr->right.sym, base);
+		if (val <= val2)
+			return;
+	}
+	if (sym->type == S_INT)
+		sprintf(str, "%d", val2);
+	else
+		sprintf(str, "0x%x", val2);
+	sym->curr.val = strdup(str);
+}
+
+static void sym_calc_visibility(struct symbol *sym)
+{
+	struct property *prop;
+	tristate tri;
+
+	/* any prompt visible? */
+	tri = no;
+	for_all_prompts(sym, prop) {
+		prop->visible.tri = expr_calc_value(prop->visible.expr);
+		tri = EXPR_OR(tri, prop->visible.tri);
+	}
+	if (tri == mod && (sym->type != S_TRISTATE || modules_val == no))
+		tri = yes;
+	if (sym->visible != tri) {
+		sym->visible = tri;
+		sym_set_changed(sym);
+	}
+	if (sym_is_choice_value(sym))
+		return;
+	tri = no;
+	if (sym->rev_dep.expr)
+		tri = expr_calc_value(sym->rev_dep.expr);
+	if (tri == mod && sym_get_type(sym) == S_BOOLEAN)
+		tri = yes;
+	if (sym->rev_dep.tri != tri) {
+		sym->rev_dep.tri = tri;
+		sym_set_changed(sym);
+	}
+}
+
+static struct symbol *sym_calc_choice(struct symbol *sym)
+{
+	struct symbol *def_sym;
+	struct property *prop;
+	struct expr *e;
+
+	/* is the user choice visible? */
+	def_sym = sym->def[S_DEF_USER].val;
+	if (def_sym) {
+		sym_calc_visibility(def_sym);
+		if (def_sym->visible != no)
+			return def_sym;
+	}
+
+	/* any of the defaults visible? */
+	for_all_defaults(sym, prop) {
+		prop->visible.tri = expr_calc_value(prop->visible.expr);
+		if (prop->visible.tri == no)
+			continue;
+		def_sym = prop_get_symbol(prop);
+		sym_calc_visibility(def_sym);
+		if (def_sym->visible != no)
+			return def_sym;
+	}
+
+	/* just get the first visible value */
+	prop = sym_get_choice_prop(sym);
+	expr_list_for_each_sym(prop->expr, e, def_sym) {
+		sym_calc_visibility(def_sym);
+		if (def_sym->visible != no)
+			return def_sym;
+	}
+
+	/* no choice? reset tristate value */
+	sym->curr.tri = no;
+	return NULL;
+}
+
+void sym_calc_value(struct symbol *sym)
+{
+	struct symbol_value newval, oldval;
+	struct property *prop;
+	struct expr *e;
+
+	if (!sym)
+		return;
+
+	if (sym->flags & SYMBOL_VALID)
+		return;
+	sym->flags |= SYMBOL_VALID;
+
+	oldval = sym->curr;
+
+	switch (sym->type) {
+	case S_INT:
+	case S_HEX:
+	case S_STRING:
+		newval = symbol_empty.curr;
+		break;
+	case S_BOOLEAN:
+	case S_TRISTATE:
+		newval = symbol_no.curr;
+		break;
+	default:
+		sym->curr.val = sym->name;
+		sym->curr.tri = no;
+		return;
+	}
+	if (!sym_is_choice_value(sym))
+		sym->flags &= ~SYMBOL_WRITE;
+
+	sym_calc_visibility(sym);
+
+	/* set default if recursively called */
+	sym->curr = newval;
+
+	switch (sym_get_type(sym)) {
+	case S_BOOLEAN:
+	case S_TRISTATE:
+		if (sym_is_choice_value(sym) && sym->visible == yes) {
+			prop = sym_get_choice_prop(sym);
+			newval.tri = (prop_get_symbol(prop)->curr.val == sym) ? yes : no;
+		} else {
+			if (sym->visible != no) {
+				/* if the symbol is visible use the user value
+				 * if available, otherwise try the default value
+				 */
+				sym->flags |= SYMBOL_WRITE;
+				if (sym_has_value(sym)) {
+					newval.tri = EXPR_AND(sym->def[S_DEF_USER].tri,
+							      sym->visible);
+					goto calc_newval;
+				}
+			}
+			if (sym->rev_dep.tri != no)
+				sym->flags |= SYMBOL_WRITE;
+			if (!sym_is_choice(sym)) {
+				prop = sym_get_default_prop(sym);
+				if (prop) {
+					sym->flags |= SYMBOL_WRITE;
+					newval.tri = EXPR_AND(expr_calc_value(prop->expr),
+							      prop->visible.tri);
+				}
+			}
+		calc_newval:
+			newval.tri = EXPR_OR(newval.tri, sym->rev_dep.tri);
+		}
+		if (newval.tri == mod && sym_get_type(sym) == S_BOOLEAN)
+			newval.tri = yes;
+		break;
+	case S_STRING:
+	case S_HEX:
+	case S_INT:
+		if (sym->visible != no) {
+			sym->flags |= SYMBOL_WRITE;
+			if (sym_has_value(sym)) {
+				newval.val = sym->def[S_DEF_USER].val;
+				break;
+			}
+		}
+		prop = sym_get_default_prop(sym);
+		if (prop) {
+			struct symbol *ds = prop_get_symbol(prop);
+			if (ds) {
+				sym->flags |= SYMBOL_WRITE;
+				sym_calc_value(ds);
+				newval.val = ds->curr.val;
+			}
+		}
+		break;
+	default:
+		;
+	}
+
+	if (sym->flags & SYMBOL_AUTO)
+		sym->flags &= ~SYMBOL_WRITE;
+
+	sym->curr = newval;
+	if (sym_is_choice(sym) && newval.tri == yes)
+		sym->curr.val = sym_calc_choice(sym);
+	sym_validate_range(sym);
+
+	if (memcmp(&oldval, &sym->curr, sizeof(oldval))) {
+		sym_set_changed(sym);
+		if (modules_sym == sym) {
+			sym_set_all_changed();
+			modules_val = modules_sym->curr.tri;
+		}
+	}
+
+	if (sym_is_choice(sym)) {
+		struct symbol *choice_sym;
+		int flags = sym->flags & (SYMBOL_CHANGED | SYMBOL_WRITE);
+
+		prop = sym_get_choice_prop(sym);
+		expr_list_for_each_sym(prop->expr, e, choice_sym) {
+			choice_sym->flags |= flags;
+			if (flags & SYMBOL_CHANGED)
+				sym_set_changed(choice_sym);
+		}
+	}
+}
+
+void sym_clear_all_valid(void)
+{
+	struct symbol *sym;
+	int i;
+
+	for_all_symbols(i, sym)
+		sym->flags &= ~SYMBOL_VALID;
+	sym_add_change_count(1);
+	if (modules_sym)
+		sym_calc_value(modules_sym);
+}
+
+void sym_set_changed(struct symbol *sym)
+{
+	struct property *prop;
+
+	sym->flags |= SYMBOL_CHANGED;
+	for (prop = sym->prop; prop; prop = prop->next) {
+		if (prop->menu)
+			prop->menu->flags |= MENU_CHANGED;
+	}
+}
+
+void sym_set_all_changed(void)
+{
+	struct symbol *sym;
+	int i;
+
+	for_all_symbols(i, sym)
+		sym_set_changed(sym);
+}
+
+bool sym_tristate_within_range(struct symbol *sym, tristate val)
+{
+	int type = sym_get_type(sym);
+
+	if (sym->visible == no)
+		return false;
+
+	if (type != S_BOOLEAN && type != S_TRISTATE)
+		return false;
+
+	if (type == S_BOOLEAN && val == mod)
+		return false;
+	if (sym->visible <= sym->rev_dep.tri)
+		return false;
+	if (sym_is_choice_value(sym) && sym->visible == yes)
+		return val == yes;
+	return val >= sym->rev_dep.tri && val <= sym->visible;
+}
+
+bool sym_set_tristate_value(struct symbol *sym, tristate val)
+{
+	tristate oldval = sym_get_tristate_value(sym);
+
+	if (oldval != val && !sym_tristate_within_range(sym, val))
+		return false;
+
+	if (!(sym->flags & SYMBOL_DEF_USER)) {
+		sym->flags |= SYMBOL_DEF_USER;
+		sym_set_changed(sym);
+	}
+	/*
+	 * setting a choice value also resets the new flag of the choice
+	 * symbol and all other choice values.
+	 */
+	if (sym_is_choice_value(sym) && val == yes) {
+		struct symbol *cs = prop_get_symbol(sym_get_choice_prop(sym));
+		struct property *prop;
+		struct expr *e;
+
+		cs->def[S_DEF_USER].val = sym;
+		cs->flags |= SYMBOL_DEF_USER;
+		prop = sym_get_choice_prop(cs);
+		for (e = prop->expr; e; e = e->left.expr) {
+			if (e->right.sym->visible != no)
+				e->right.sym->flags |= SYMBOL_DEF_USER;
+		}
+	}
+
+	sym->def[S_DEF_USER].tri = val;
+	if (oldval != val)
+		sym_clear_all_valid();
+
+	return true;
+}
+
+tristate sym_toggle_tristate_value(struct symbol *sym)
+{
+	tristate oldval, newval;
+
+	oldval = newval = sym_get_tristate_value(sym);
+	do {
+		switch (newval) {
+		case no:
+			newval = mod;
+			break;
+		case mod:
+			newval = yes;
+			break;
+		case yes:
+			newval = no;
+			break;
+		}
+		if (sym_set_tristate_value(sym, newval))
+			break;
+	} while (oldval != newval);
+	return newval;
+}
+
+bool sym_string_valid(struct symbol *sym, const char *str)
+{
+	signed char ch;
+
+	switch (sym->type) {
+	case S_STRING:
+		return true;
+	case S_INT:
+		ch = *str++;
+		if (ch == '-')
+			ch = *str++;
+		if (!isdigit(ch))
+			return false;
+		if (ch == '0' && *str != 0)
+			return false;
+		while ((ch = *str++)) {
+			if (!isdigit(ch))
+				return false;
+		}
+		return true;
+	case S_HEX:
+		if (str[0] == '0' && (str[1] == 'x' || str[1] == 'X'))
+			str += 2;
+		ch = *str++;
+		do {
+			if (!isxdigit(ch))
+				return false;
+		} while ((ch = *str++));
+		return true;
+	case S_BOOLEAN:
+	case S_TRISTATE:
+		switch (str[0]) {
+		case 'y': case 'Y':
+		case 'm': case 'M':
+		case 'n': case 'N':
+			return true;
+		}
+		return false;
+	default:
+		return false;
+	}
+}
+
+bool sym_string_within_range(struct symbol *sym, const char *str)
+{
+	struct property *prop;
+	int val;
+
+	switch (sym->type) {
+	case S_STRING:
+		return sym_string_valid(sym, str);
+	case S_INT:
+		if (!sym_string_valid(sym, str))
+			return false;
+		prop = sym_get_range_prop(sym);
+		if (!prop)
+			return true;
+		val = strtol(str, NULL, 10);
+		return val >= sym_get_range_val(prop->expr->left.sym, 10) &&
+		       val <= sym_get_range_val(prop->expr->right.sym, 10);
+	case S_HEX:
+		if (!sym_string_valid(sym, str))
+			return false;
+		prop = sym_get_range_prop(sym);
+		if (!prop)
+			return true;
+		val = strtol(str, NULL, 16);
+		return val >= sym_get_range_val(prop->expr->left.sym, 16) &&
+		       val <= sym_get_range_val(prop->expr->right.sym, 16);
+	case S_BOOLEAN:
+	case S_TRISTATE:
+		switch (str[0]) {
+		case 'y': case 'Y':
+			return sym_tristate_within_range(sym, yes);
+		case 'm': case 'M':
+			return sym_tristate_within_range(sym, mod);
+		case 'n': case 'N':
+			return sym_tristate_within_range(sym, no);
+		}
+		return false;
+	default:
+		return false;
+	}
+}
+
+bool sym_set_string_value(struct symbol *sym, const char *newval)
+{
+	const char *oldval;
+	char *val;
+	int size;
+
+	switch (sym->type) {
+	case S_BOOLEAN:
+	case S_TRISTATE:
+		switch (newval[0]) {
+		case 'y': case 'Y':
+			return sym_set_tristate_value(sym, yes);
+		case 'm': case 'M':
+			return sym_set_tristate_value(sym, mod);
+		case 'n': case 'N':
+			return sym_set_tristate_value(sym, no);
+		}
+		return false;
+	default:
+		;
+	}
+
+	if (!sym_string_within_range(sym, newval))
+		return false;
+
+	if (!(sym->flags & SYMBOL_DEF_USER)) {
+		sym->flags |= SYMBOL_DEF_USER;
+		sym_set_changed(sym);
+	}
+
+	oldval = sym->def[S_DEF_USER].val;
+	size = strlen(newval) + 1;
+	if (sym->type == S_HEX && (newval[0] != '0' || (newval[1] != 'x' && newval[1] != 'X'))) {
+		size += 2;
+		sym->def[S_DEF_USER].val = val = malloc(size);
+		*val++ = '0';
+		*val++ = 'x';
+	} else if (!oldval || strcmp(oldval, newval))
+		sym->def[S_DEF_USER].val = val = malloc(size);
+	else
+		return true;
+
+	strcpy(val, newval);
+	free((void *)oldval);
+	sym_clear_all_valid();
+
+	return true;
+}
+
+const char *sym_get_string_value(struct symbol *sym)
+{
+	tristate val;
+
+	switch (sym->type) {
+	case S_BOOLEAN:
+	case S_TRISTATE:
+		val = sym_get_tristate_value(sym);
+		switch (val) {
+		case no:
+			return "n";
+		case mod:
+			return "m";
+		case yes:
+			return "y";
+		}
+		break;
+	default:
+		;
+	}
+	return (const char *)sym->curr.val;
+}
+
+bool sym_is_changable(struct symbol *sym)
+{
+	return sym->visible > sym->rev_dep.tri;
+}
+
+struct symbol *sym_lookup(const char *name, int isconst)
+{
+	struct symbol *symbol;
+	const char *ptr;
+	char *new_name;
+	int hash = 0;
+
+	if (name) {
+		if (name[0] && !name[1]) {
+			switch (name[0]) {
+			case 'y': return &symbol_yes;
+			case 'm': return &symbol_mod;
+			case 'n': return &symbol_no;
+			}
+		}
+		for (ptr = name; *ptr; ptr++)
+			hash += *ptr;
+		hash &= 0xff;
+
+		for (symbol = symbol_hash[hash]; symbol; symbol = symbol->next) {
+			if (!strcmp(symbol->name, name)) {
+				if ((isconst && symbol->flags & SYMBOL_CONST) ||
+				    (!isconst && !(symbol->flags & SYMBOL_CONST)))
+					return symbol;
+			}
+		}
+		new_name = strdup(name);
+	} else {
+		new_name = NULL;
+		hash = 256;
+	}
+
+	symbol = malloc(sizeof(*symbol));
+	memset(symbol, 0, sizeof(*symbol));
+	symbol->name = new_name;
+	symbol->type = S_UNKNOWN;
+	if (isconst)
+		symbol->flags |= SYMBOL_CONST;
+
+	symbol->next = symbol_hash[hash];
+	symbol_hash[hash] = symbol;
+
+	return symbol;
+}
+
+struct symbol *sym_find(const char *name)
+{
+	struct symbol *symbol = NULL;
+	const char *ptr;
+	int hash = 0;
+
+	if (!name)
+		return NULL;
+
+	if (name[0] && !name[1]) {
+		switch (name[0]) {
+		case 'y': return &symbol_yes;
+		case 'm': return &symbol_mod;
+		case 'n': return &symbol_no;
+		}
+	}
+	for (ptr = name; *ptr; ptr++)
+		hash += *ptr;
+	hash &= 0xff;
+
+	for (symbol = symbol_hash[hash]; symbol; symbol = symbol->next) {
+		if (!strcmp(symbol->name, name) &&
+		    !(symbol->flags & SYMBOL_CONST))
+				break;
+	}
+
+	return symbol;
+}
+
+struct symbol **sym_re_search(const char *pattern)
+{
+	struct symbol *sym, **sym_arr = NULL;
+	int i, cnt, size;
+	regex_t re;
+
+	cnt = size = 0;
+	/* Skip if empty */
+	if (strlen(pattern) == 0)
+		return NULL;
+	if (regcomp(&re, pattern, REG_EXTENDED|REG_NOSUB|REG_ICASE))
+		return NULL;
+
+	for_all_symbols(i, sym) {
+		if (sym->flags & SYMBOL_CONST || !sym->name)
+			continue;
+		if (regexec(&re, sym->name, 0, NULL, 0))
+			continue;
+		if (cnt + 1 >= size) {
+			void *tmp = sym_arr;
+			size += 16;
+			sym_arr = realloc(sym_arr, size * sizeof(struct symbol *));
+			if (!sym_arr) {
+				free(tmp);
+				return NULL;
+			}
+		}
+		sym_arr[cnt++] = sym;
+	}
+	if (sym_arr)
+		sym_arr[cnt] = NULL;
+	regfree(&re);
+
+	return sym_arr;
+}
+
+
+struct symbol *sym_check_deps(struct symbol *sym);
+
+static struct symbol *sym_check_expr_deps(struct expr *e)
+{
+	struct symbol *sym;
+
+	if (!e)
+		return NULL;
+	switch (e->type) {
+	case E_OR:
+	case E_AND:
+		sym = sym_check_expr_deps(e->left.expr);
+		if (sym)
+			return sym;
+		return sym_check_expr_deps(e->right.expr);
+	case E_NOT:
+		return sym_check_expr_deps(e->left.expr);
+	case E_EQUAL:
+	case E_UNEQUAL:
+		sym = sym_check_deps(e->left.sym);
+		if (sym)
+			return sym;
+		return sym_check_deps(e->right.sym);
+	case E_SYMBOL:
+		return sym_check_deps(e->left.sym);
+	default:
+		break;
+	}
+	printf("Oops! How to check %d?\n", e->type);
+	return NULL;
+}
+
+/* return NULL when dependencies are OK */
+struct symbol *sym_check_deps(struct symbol *sym)
+{
+	struct symbol *sym2;
+	struct property *prop;
+
+	if (sym->flags & SYMBOL_CHECK) {
+		fprintf(stderr, "%s:%d:error: found recursive dependency: %s",
+		        sym->prop->file->name, sym->prop->lineno, sym->name);
+		return sym;
+	}
+	if (sym->flags & SYMBOL_CHECKED)
+		return NULL;
+
+	sym->flags |= (SYMBOL_CHECK | SYMBOL_CHECKED);
+	sym2 = sym_check_expr_deps(sym->rev_dep.expr);
+	if (sym2)
+		goto out;
+
+	for (prop = sym->prop; prop; prop = prop->next) {
+		if (prop->type == P_CHOICE || prop->type == P_SELECT)
+			continue;
+		sym2 = sym_check_expr_deps(prop->visible.expr);
+		if (sym2)
+			goto out;
+		if (prop->type != P_DEFAULT || sym_is_choice(sym))
+			continue;
+		sym2 = sym_check_expr_deps(prop->expr);
+		if (sym2)
+			goto out;
+	}
+out:
+	if (sym2)
+		fprintf(stderr, " -> %s%s", sym->name, sym2 == sym? "\n": "");
+	sym->flags &= ~SYMBOL_CHECK;
+	return sym2;
+}
+
+struct property *prop_alloc(enum prop_type type, struct symbol *sym)
+{
+	struct property *prop;
+	struct property **propp;
+
+	prop = malloc(sizeof(*prop));
+	memset(prop, 0, sizeof(*prop));
+	prop->type = type;
+	prop->sym = sym;
+	prop->file = current_file;
+	prop->lineno = zconf_lineno();
+
+	/* append property to the prop list of symbol */
+	if (sym) {
+		for (propp = &sym->prop; *propp; propp = &(*propp)->next)
+			;
+		*propp = prop;
+	}
+
+	return prop;
+}
+
+struct symbol *prop_get_symbol(struct property *prop)
+{
+	if (prop->expr && (prop->expr->type == E_SYMBOL ||
+			   prop->expr->type == E_LIST))
+		return prop->expr->left.sym;
+	return NULL;
+}
+
+const char *prop_get_type_name(enum prop_type type)
+{
+	switch (type) {
+	case P_PROMPT:
+		return "prompt";
+	case P_ENV:
+		return "env";
+	case P_COMMENT:
+		return "comment";
+	case P_MENU:
+		return "menu";
+	case P_DEFAULT:
+		return "default";
+	case P_CHOICE:
+		return "choice";
+	case P_SELECT:
+		return "select";
+	case P_RANGE:
+		return "range";
+	case P_UNKNOWN:
+		break;
+	}
+	return "unknown";
+}
+
+void prop_add_env(const char *env)
+{
+	struct symbol *sym, *sym2;
+	struct property *prop;
+	char *p;
+
+	sym = current_entry->sym;
+	sym->flags |= SYMBOL_AUTO;
+	for_all_properties(sym, prop, P_ENV) {
+		sym2 = prop_get_symbol(prop);
+		if (strcmp(sym2->name, env))
+			menu_warn(current_entry, "redefining environment symbol from %s",
+				  sym2->name);
+		return;
+	}
+
+	prop = prop_alloc(P_ENV, sym);
+	prop->expr = expr_alloc_symbol(sym_lookup(env, 1));
+
+	sym_env_list = expr_alloc_one(E_LIST, sym_env_list);
+	sym_env_list->right.sym = sym;
+
+	p = getenv(env);
+	if (p)
+		sym_add_default(sym, p);
+	else
+		menu_warn(current_entry, "environment variable %s undefined", env);
+}