[igt-dev] [PATCH 2/5] i915/perf: Add tests for mapped OA buffer

[Dixit, Ashutosh]

On Tue, 24 Aug 2021 11:58:42 -0700, Umesh Nerlige Ramappa wrote:
>
> >> +/**
> >> + * OA buffer size and offset.
> >> + *
> >> + * OA output buffer
> >> + *   type: 0
> >> + *   flags: mbz
> >> + *
> >> + *   After querying the info, pass (size,offset) to mmap(),
> >> + *
> >> + *   mmap(0, info.size, PROT_READ, MAP_PRIVATE, perf_fd, info.offset).
> >> + *
> >> + *   Note that only a private (not shared between processes, or across fork())
> >> + *   read-only mmapping is allowed.
> >> + *
> >> + *   Userspace must treat the incoming data as tainted, but it conforms to the OA
> >
> > What does tainted mean?
>
> I'd assume the data is changing as OA buffer reports are captured. I can
> change the comment to say that instead of tainted.

Changing is again ambiguous, I think we could just say something like:

HW is continually writing data to the mapped OA buffer and it conforms to
the OA format as specified by user config. The buffer provides reports that
have OA counters - A, B and C.