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Date: Tue, 24 Aug 2021 12:18:51 -0700
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From: "Dixit, Ashutosh" <ashutosh.dixit@intel.com>
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Subject: Re: [igt-dev] [PATCH 2/5] i915/perf: Add tests for mapped OA buffer
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To: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Cc: igt-dev@lists.freedesktop.org, Lionel G Landwerlin <lionel.g.landwerlin@intel.com>
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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.