Re: [PATCH 0/7] perf tool: add meta-data header support for pipe-mode

[Andi Kleen]

> The difficulty in pipe mode is that information needs to be written
> sequentially to the pipe. Meta data headers are usually generated
> (and also expected) at the beginning of the file (or piped output).
> To solve this problem, we introduce new synthetic record types,
> one for each meta-data type. The approach is similar to what
> is *ALREADY* used for BUILD_ID and TRACING_DATA.

The new headers need documentation in Documentation/perf.data-file-format.txt

-Andi