• Masahiro Yamada's avatar
    kconfig: reference environment variables directly and remove 'option env=' · 104daea1
    Masahiro Yamada authored
    To get access to environment variables, Kconfig needs to define a
    symbol using "option env=" syntax.  It is tedious to add a symbol entry
    for each environment variable given that we need to define much more
    such as 'CC', 'AS', 'srctree' etc. to evaluate the compiler capability
    in Kconfig.
    
    Adding '$' for symbol references is grammatically inconsistent.
    Looking at the code, the symbols prefixed with 'S' are expanded by:
     - conf_expand_value()
       This is used to expand 'arch/$ARCH/defconfig' and 'defconfig_list'
     - sym_expand_string_value()
       This is used to expand strings in 'source' and 'mainmenu'
    
    All of them are fixed values independent of user configuration.  So,
    they can be changed into the direct expansion instead of symbols.
    
    This change makes the code much cleaner.  The bounce symbols 'SRCARCH',
    'ARCH', 'SUBARCH', 'KERNELVERSION' are gone.
    
    sym_init() hard-coding 'UNAME_RELEASE' is also gone.  'UNAME_RELEASE'
    should be replaced with an environment variable.
    
    ARCH_DEFCONFIG is a normal symbol, so it should be simply referenced
    without '$' prefix.
    
    The new syntax is addicted by Make.  The variable reference needs
    parentheses, like $(FOO), but you can omit them for single-letter
    variables, like $F.  Yet, in Makefiles, people tend to use the
    parenthetical form for consistency / clarification.
    
    At this moment, only the environment variable is supported, but I will
    extend the concept of 'variable' later on.
    
    The variables are expanded in the lexer so we can simplify the token
    handling on the parser side.
    
    For example, the following code works.
    
    [Example code]
    
      config MY_TOOLCHAIN_LIST
              string
              default "My tools: CC=$(CC), AS=$(AS), CPP=$(CPP)"
    
    [Result]
    
      $ make -s alldefconfig && tail -n 1 .config
      CONFIG_MY_TOOLCHAIN_LIST="My tools: CC=gcc, AS=as, CPP=gcc -E"
    Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
    Reviewed-by: default avatarKees Cook <keescook@chromium.org>
    104daea1
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