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Diffstat (limited to 'Documentation/kbuild/kconfig-language.rst')
| -rw-r--r-- | Documentation/kbuild/kconfig-language.rst | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst index a91abb8f6840..abce88f15d7c 100644 --- a/Documentation/kbuild/kconfig-language.rst +++ b/Documentation/kbuild/kconfig-language.rst @@ -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 ----------------- |