Good morning,
I have reviewed the document and find it much easier to understand now - many thanks for the rectifications.
The shallowness of my knowledge in trace decoding prevents me from doing a detailed analysis of the design but from where I stand things are holding together. Blocks are separated cleanly in accordance with their functionality and interfaces are provided for metadata input.
That being said, in what kind of context do you see this library being used (i.e workflow)? Did you foresee a new user space application that would take trace data and feed it to the openCSD library?
Over the past few weeks I've been working on integrating coresight with Perf on both kernel and user space planes. The Perf user space tool already provides a very rich context that include support for source code analysis. As such integrating coresight trace decoding with Perf is probably a sensitive thing to do.
Before we get too far in the design I think it would be a good idea to look at how code analysis is currently done in Perf, with the goal of fitting the openCSD library with the interfaces needed to integrate with Perf.
Perf is already a well established tool for many things, re-using it can only lessen the amount of work to do and speed up community acceptance for coresight.
Mathieu
On 24 June 2015 at 07:07, Mike Leach Mike.Leach@arm.com wrote:
Hi All,
Updated document attached. Contains information on the more comprehensive trace snapshot format which we believe will be useful for exchanging trace captures for decoder testing
Regards
Mike
Mike Leach +44 (0)1254 893911 (Direct) Principal Engineer +44 (0)1254 893900 (Main) Arm Blackburn Design Centre +44 (0)1254 893901 (Fax) Belthorn House Walker Rd mailto:mike.leach@arm.com Guide Blackburn BB1 2QE
-----Original Message----- From: CoreSight [mailto:coresight-bounces@lists.linaro.org] On Behalf Of Mike Leach Sent: 22 June 2015 17:55 To: Mathieu Poirier Cc: coresight@lists.linaro.org Subject: RE: API Document
Hi Mathieu,
Thanks for the feedback. I'll not comment individually on each section other than to say I agree that there is inconsistent terminology used and have addressed each element you pointed out.
There will be a new version of the document published shortly which will include the corrections, along with a new section on the updated snapshot format that was discussed at the last phone meeting.
To the C++ question - the answer is yes. The work we are currently undertaking on the infrastructure and packet decoders is implemented in C++.
Regards
Mike
Mike Leach +44 (0)1254 893911 (Direct) Principal Engineer +44 (0)1254 893900 (Main) Arm Blackburn Design Centre +44 (0)1254 893901 (Fax) Belthorn House Walker Rd mailto:mike.leach@arm.com Guide Blackburn BB1 2QE
-----Original Message----- From: Mathieu Poirier [mailto:mathieu.poirier@linaro.org] Sent: 16 June 2015 17:52 To: Mike Leach Cc: coresight@lists.linaro.org Subject: Re: API Document
Good day Mike,
I reviewed the document that was submitted and have the following comments - at this time most of them surround the terminology that was used. I may be a little slow to catch on but for someone not familiar with trace decoding engines it is extremely difficult to wrap one's head around new concepts when variations are used.
I read the entire document twice but can't provide comments on section 2.3 and beyond before the following points are clarified.
Section 2.1.1:
- "Where the source is a core the decoder will be a PE decoder..." :
Are we still talking about the "packet trace decoder" or something else?
- "The protocol block will require..." : Are we talking about the
"Protocol decode block"?
- The reader must assume the "generic trace primitives" are the same
as the "generic trace elements" introduced in chapter 2.1.5. If so the latter should be used throughout the document.
Section 2.1.2:
- "The trace formatted frame decoder is provided..." : Are we talking
about the "trace frame deformatter". Without using the same terms, there is no way to tell.
- "A decode block can be attached..." : What is a "decode block"? I
must assume we are referring to a "Protocol decode block".
Section 2.1.4:
- "Packet processors and decoders can be...": Are we talking about
the packet processor and packet "trace decoder" presented in section 2.1.1? If so "trace decoder" needs to be referenced explicitly.
Figure 1:
- Is the "Trace Decode Block" the "Protocol decode block" presented
in section 2.1.1? If so section 2.1.1 needs to be modified to include the "Trace Frame Deformatter". Following the figure I think the latter should be presented first, followed by the "packet processor" and "packet decoder" descriptions.
One of the main provider of trace stream to the "Trace Decode Block" will be the user space Perf tool. I am currently working on how the gap between Perf and the Trace Decode Block will be bridged.
Figure 2:
- One must assume the green box labelled "stream protocol decode
block" is the same as what was presented in Figure 1. If so the same names need to be used in both figures.
I would add "Perf" in the "formatted trace source" box.
Should the "Trace Formatted Frame Decoder" be introduced somewhere
in the documentation? Or maybe it was under a different name?
- "... is the Stream Protocol decode block as previously described".
I must assume this is the "Protocol Decode Block" introduced in section 2.1.1. If so the same terminology has to be use throughout the document.
Section 3.1:
I noticed that C++ syntax was used - is this strictly for documentation purposes or should I deduce that ARM favours using C++ in the implementation?
Best regards, Mathieu
On 27 May 2015 at 10:29, Mike Leach Mike.Leach@arm.com wrote:
Hi,
As discussed I have attached the API document that describes the design
and current implementation of a CoreSight decoder library framework that we have been working on within ARM.
This is very much a work in progress (both the document and the API) -
but
questions / comments etc. are always welcome.
The document does have a distribution list on the front but it is not
limited
by this so if I have missed anyone off I apologise.
Regards
Mike
Mike Leach +44 (0)1254 893911 (Direct) Principal Engineer +44 (0)1254 893900 (Main) Arm Blackburn Design Centre +44 (0)1254 893901 (Fax) Belthorn House Walker Rd mailto:mike.leach@arm.com Guide Blackburn BB1 2QE
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