CTF: University project

[Dominik Taborsky]

On Sun, 30 Nov 2014 22:26:18 +0100, Chris Johns <chrisj at rtems.org> wrote:

> On 1/12/2014 12:17 am, Dominik Taborsky wrote:
>> On Sun, 30 Nov 2014 01:27:06 +0100, Chris Johns <chrisj at rtems.org>  
>> wrote:

...

>>>
>>> One area that has plenty of work that needs doing plus ways to
>>> innovate is trace. Jennifer is adding trace support to the capture
>>> engine [1] for SMP and I have written a trace linker [2] that has
>>> support to trace calls using printk. We need to hook all this together
>>> to make a workable solution for users and we are currently looking at
>>> the Common Trace Format (CTF) [3] to do this. Generating CTF lets us
>>> integrate with Babletrace and the Linux Trace Toolkit Viewer (LTTV).
>>>
>>> The trace support we are adding attempts to solve some tough user
>>> requirements from the space community such as instrumenting and
>>> tracing software at the object level rather than instrumenting at the
>>> source level. This means you take software that is compiled and
>>> production ready and link in trace support. The support needs to be
>>> efficient because it is a target side software only trace.
>>> Transporting data off target needs to be generic and flexible because
>>> we have so many different target types with differing hardware.
>>>
>>> The work involves adding suitable support to the capture engine to
>>> extract the trace data and convert it to the CTF format. This may be
>>> on target or off target depending on the load it places on the target.
>>> We have lots of pieces of code in place but the code is new and green
>>> so you would need to work across all parts. We need support for
>>> generating trigger and trace control maps and this may be linked to
>>> the CTF format and Babeltrace. There will be work at real-time capture
>>> level, the trace linking parts on the host, and CTF integrations.
>>>
>>> Joel and I met three of the EfficiOS people at GSoC this year and
>>> discussed this work so we would work with them.
>>>
>>
>> So you're working on the capture engine itself,
>
> I am not but Jennifer is. I am not sure what remaining work she has  
> planned. I have been doing little bits with the trace linker and that  
> code needs work to integrate with the capture engine. For example  
> trigger maps plus other controls.
>
>> while my job would be to compile the trace captured into a CTF,
>
> If you are lucky this might be the case. How we integrate to that code  
> base has not been looked at. Using this format lets us use the nice  
> front end tools that exist. Any changes will require us working with the 
> upstream project.

I'm not planning to change it, after my blitz look at it, it seems very  
comprehensive.

>
>> possibly transmitting it over to some other machine and decompiling
>> it again?
>
> Yes these tasks exist. The transmission task is complex because of the  
> possible overhead it can create. As Joel said we need to create trigger  
> maps and merge them into the system some how plus there are possible  
> stability issues where the trace overloads the target to be considered.

These are implementation details, right now I worry about design, i.e.  
what am I supposed to do... :)

>
> The capture engine has 2 parts, the capture part and a command line  
> interface via the RTEMS shell. This work relates to just the capture  
> engine code and not the CLI.
>
>>
>> To make sure, this means implementing some kind of state automata on
>> both ends, right?
>>
>
> I am not sure this process is that exact.

It seems to me like that, but let's skip that for now.


Right now I worry about my goals. I need to give my teacher some kind of  
roadmap what I'll be doing. After that I'll dive into the code.

I need a milestone to achieve during February and then possibly another  
during June. Can you select one milestone for February using an educated  
guess what could be achieved, perhaps only as alpha version? I just need  
something to aim at.

Thanks for your patience with me, Chris! :)


Dominik

>
> Chris
>
>>
>>> Chris
>>>
>>> [1] https://devel.rtems.org/browser/rtems/cpukit/libmisc/capture
>>> [2] https://devel.rtems.org/browser/rtems-tools/linkers/rtems-tld.cpp
>>> [3] http://www.efficios.com/ctf