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    SubjectRe: [RFC/Requirements/Design] h/w error reporting
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    On Wed, 2010-11-10 at 10:09 -0500, Steven Rostedt wrote:
    >
    > > sure the second way is the only way out, but you still need to come up
    > > with a trace data format and a control ABI.
    >
    > Great! Let's start with that then. Could you list some of the basic
    > needs of perf?

    Needs for what? I've already got a full control ABI and I can already
    redirect output to other buffers ;-)

    I don't have enumeration of what all is redirected to what, I pretend
    that people know wth they're doing.. so if you want session lists of
    what tracepoints are active on which buffers and the like you'll have to
    come up with something for that.

    As for the buffer, I prefer a u64 aligned data stream, but the very
    least I need is frame encapsulation. What I don't want _ever_ is stupid
    sub-buffers. And no they're not needed, see the discussion about sync
    markers a while back.

    I also don't want to support the stupid concurrent read/write from tail.

    What I do want is both mmap() and splice(), this means buffer size needs
    to be specified at buffer creation.

    I currently support overwrite (flight-recorder) and non-overwrite modes
    depending on PROT_WRITE, I guess that can easily be pushed into the
    buffer create call.

    As to the mmap() part, it needs a control page to expose the head/tail
    pointers and some data.

    And as you know I need to write > PAGE_SIZE entries.


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