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    SubjectRe: [Announce] Linux-tiny project revival
    Rob Landley <> wrote:
    | The "change every printk in the kernel" suggestion came from me trying to
    | figure out how to get the printk() calls below a certain log level to
    | optimize out and not take up space in the binary.
    | The above doesn't address the original cause of the thread, as far as I can
    | tell.

    It does, provided you change the macro definition to:

    #define _printk(level, str, ...) \
    do { \
    if (sizeof(level) == 1) /* continued printk */\
    actual_printk(str, __VA_ARGS__); \
    else if ((level[1] - '0') < CONFIG_PRINTK_DOICARE) \
    actual_printk(level str, __VA_ARGS__); \
    } while(0);
    #define printk(level_str, ...) _printk(level_str, __VA_ARGS__)

    Gcc will do constant folding on the string subscripts, and remove the
    code and the string constants for calls above the desired level.

    This is basically the same as I proposed in my earlier message [*],
    but with the disadvantage that you need to modify all printk() calls
    without an explicit level and add the ugly comma to the KERN_* macros.
    Just compile the code in my message with -O and -S and you will see
    that the KERN_NOTICE call and the corresponding string literal are
    optimized away.


    Dick Streefland //// Altium BV (@ @)

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      Last update: 2007-09-28 16:39    [W:0.090 / U:1.768 seconds]
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