kconfig: Add transitional symbol attribute for migration support

new file mode 100644
index 000000000000..a75ed3b2fe5e
@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: GPL-2.0
+# Test that transitional symbols cannot have properties other than help
+
+config BAD_DEFAULT
+	bool
+	transitional
+	default y
+	help
+	  This transitional symbol illegally has a default property.
+
+config BAD_PROMPT
+	bool
+	transitional
+	prompt "Bad prompt"
+	help
+	  This transitional symbol illegally has a prompt.
+
+config BAD_SELECT
+	bool
+	transitional
+	select OTHER_SYMBOL
+	help
+	  This transitional symbol illegally has a select.
+
+config BAD_IMPLY
+	bool
+	transitional
+	imply OTHER_SYMBOL
+	help
+	  This transitional symbol illegally has an imply.
+
+config BAD_DEPENDS
+	bool
+	transitional
+	depends on OTHER_SYMBOL
+	help
+	  This transitional symbol illegally has a depends.
+
+config BAD_RANGE
+	int
+	transitional
+	range 1 10
+	help
+	  This transitional symbol illegally has a range.
+
+config BAD_NO_TYPE
+	transitional
+	help
+	  This transitional symbol illegally has no type specified.
+
+config OTHER_SYMBOL
+	bool

100 lines not on this page · raw message

index 9c2cdfc33c6f..6d2c92c6095d 100644
@@ -126,6 +126,7 @@ n	[A-Za-z0-9_-]
 "select"		return T_SELECT;
 "source"		return T_SOURCE;
 "string"		return T_STRING;
+"transitional"		return T_TRANSITIONAL;
 "tristate"		return T_TRISTATE;
 "visible"		return T_VISIBLE;
 "||"			return T_OR;

71 lines not on this page · raw message

new file mode 100644
index 000000000000..7dffb5b0833f
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+"""
+Test that transitional symbols with invalid properties are rejected.
+
+Transitional symbols can only have help sections. Any other properties
+(default, select, depends, etc.) should cause a parser error.
+"""
+
+def test(conf):
+    # This should fail with exit code 1 due to invalid transitional symbol
+    assert conf.olddefconfig() == 1
+
+    # Check that the error message is about transitional symbols
+    assert conf.stderr_contains('expected_stderr')

new file mode 100644
index 000000000000..b52db4f680f4
@@ -0,0 +1,7 @@
+Kconfig:46:warning: config symbol defined without type
+Kconfig:7: error: transitional symbols can only have help sections
+Kconfig:14: error: transitional symbols can only have help sections
+Kconfig:21: error: transitional symbols can only have help sections
+Kconfig:28: error: transitional symbols can only have help sections
+Kconfig:32: error: transitional symbols can only have help sections
+Kconfig:42: error: transitional symbols can only have help sections

new file mode 100644
index 000000000000..029382a54d47
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0
+"""
+Test transitional symbol migration functionality for all Kconfig types.
+
+This tests that:
+1. OLD_* options in existing .config cause NEW_* options to be set
+2. OLD_* options are not written to the new .config file
+3. NEW_* options appear in the new .config file with correct values
+4. All Kconfig types work correctly: bool, tristate, string, hex, int
+5. User-set NEW values take precedence over conflicting OLD transitional values
+"""
+
+def test(conf):
+    # Run olddefconfig to process the migration with the initial config
+    assert conf.olddefconfig(dot_config='initial_config') == 0
+
+    # Check that the configuration matches expected output
+    assert conf.config_contains('expected_config')

new file mode 100644
index 000000000000..846e9ddcab91
@@ -0,0 +1,12 @@
+CONFIG_MODULES=y
+CONFIG_NEW_BOOL=y
+CONFIG_NEW_TRISTATE=m
+CONFIG_NEW_STRING="test string"
+CONFIG_NEW_HEX=0x1234
+CONFIG_NEW_INT=42
+# CONFIG_NEW_BOOL_PRECEDENCE is not set
+CONFIG_NEW_STRING_PRECEDENCE="user value"
+CONFIG_NEW_TRISTATE_PRECEDENCE=y
+CONFIG_NEW_HEX_PRECEDENCE=0xABCD
+CONFIG_NEW_INT_PRECEDENCE=100
+# CONFIG_REGULAR_OPTION is not set

new file mode 100644
index 000000000000..e648a65e504c
@@ -0,0 +1,16 @@
+CONFIG_MODULES=y
+CONFIG_OLD_BOOL=y
+CONFIG_OLD_TRISTATE=m
+CONFIG_OLD_STRING="test string"
+CONFIG_OLD_HEX=0x1234
+CONFIG_OLD_INT=42
+# CONFIG_NEW_BOOL_PRECEDENCE is not set
+CONFIG_OLD_BOOL_PRECEDENCE=y
+CONFIG_NEW_STRING_PRECEDENCE="user value"
+CONFIG_OLD_STRING_PRECEDENCE="old value"
+CONFIG_NEW_TRISTATE_PRECEDENCE=y
+CONFIG_OLD_TRISTATE_PRECEDENCE=m
+CONFIG_NEW_HEX_PRECEDENCE=0xABCD
+CONFIG_OLD_HEX_PRECEDENCE=0x5678
+CONFIG_NEW_INT_PRECEDENCE=100
+CONFIG_OLD_INT_PRECEDENCE=200

index a91abb8f6840..abce88f15d7c 100644
@@ -232,6 +232,38 @@ applicable everywhere (see syntax).
   enables the third modular state for all config symbols.
   At most one symbol may have the "modules" option set.
 
+- transitional attribute: "transitional"
+  This declares the symbol as transitional, meaning it should be processed
+  during configuration but omitted from newly written .config files.
+  Transitional symbols are useful for backward compatibility during config
+  option migrations - they allow olddefconfig to process existing .config
+  files while ensuring the old option doesn't appear in new configurations.
+
+  A transitional symbol:
+  - Has no prompt (is not visible to users in menus)
+  - Is processed normally during configuration (values are read and used)
+  - Can be referenced in default expressions of other symbols
+  - Is not written to new .config files
+  - Cannot have any other properties (it is a pass-through option)
+
+  Example migration from OLD_NAME to NEW_NAME::
+
+    config NEW_NAME
+	bool "New option name"
+	default OLD_NAME
+	help
+	  This replaces the old CONFIG_OLD_NAME option.
+
+    config OLD_NAME
+	bool
+	transitional
+	help
+	  Transitional config for OLD_NAME to NEW_NAME migration.
+
+  With this setup, existing .config files with "CONFIG_OLD_NAME=y" will
+  result in "CONFIG_NEW_NAME=y" being set, while CONFIG_OLD_NAME will be
+  omitted from newly written .config files.
+
 Menu dependencies
 -----------------