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    SubjectRe: [RFC PATCH 2/5] tracing/events: nicer print format for parsing
    Steven Rostedt wrote:
    > On Tue, 9 Jun 2009, Frederic Weisbecker wrote:
    >>
    >>> The language that is added by this patch is of the following:
    >>>
    >>> * FMT := constant string FMT | COMMAND FMT | empty
    >>> * COMMAND := <TYPE:FIELD> | <mask:FIELD:DELIM:MASKS> | <sym:FIELD:SYMBOLS> |
    >>> * <if:FIELD:TRUE:FALSE>
    >>> * TYPE := int | hex | ptr | string | strarray
    >>> * FIELD := defined by the event structure
    >>> * MASKS := MASK=NAME,MASKS | MASK=NAME
    >>> * MASK := the bit mask to match
    >>> * DELIM := delimiter to separate the fields. None and ':' are both allowed
    >>> * SYMBOLS := SYM=NAME,SYMBOLS | SYM=NAME
    >>> * SYM := the symbol value to test against
    >>> * TRUE := print when field is non zero
    >>> * FALSE := print when field is zero or NULL
    >>> * NAME := the name to write when a match is found
    >>> *
    >>> * A '\<' would print '<'
    >>
    >> But I wonder if the above new language is not breaking the charm
    >> of the TRACE_EVENT(), which charm is that it's easy to implement (hopefully).
    >>
    >> Everyone knows the printk formats. And I guess this new thing is easy and
    >> quick to learn. But because it's a new unknown language, the TRACE_EVENT
    >> will become less readable, less reachable for newcomers in TRACE_EVENT.
    >
    > I tried to avoid this too, but when I started writing a tool in C that
    > would parse the format file, I found that the printf was horrible.
    >
    > Note, I will still keep the TP_printk() macro, that will not change. The
    > new macro is TP_FORMAT() that preforms the tags. Thus, if you really want
    > it to print out, you can use TP_printk, but the user space tools that read
    > the binary will not know how to read it unless the printk is simple.
    >
    > I really want to keep this language simple. If anyone has any better
    > ideas, I'm all for it.
    >
    > I barfed when I saw this in irq_handler_entry:
    >
    > print fmt: "irq=%d handler=%s", REC->irq, (char *)((void *)REC + REC->__data_loc_name)
    >

    I barfed too when I saw this. Introducing a new format is
    very meaningful. And this print format looks well.
    Good Work!

    I'm trying to write user-space tools. Could you tell me your tools'
    developing status? And the aim of these tools? Will it be public?

    I'm wandering whether I should stop this trying.

    Lai.



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