Re: [Qemu-devel] GSoC mentor summit QEMU users session

[Fabien Chouteau <chouteau@adacore.com>]

On 04/11/2011 13:04, Stefan Hajnoczi wrote:
> On Fri, Nov 4, 2011 at 9:53 AM, Fabien Chouteau <chouteau@adacore.com> wrote:
>> On 04/11/2011 09:36, Stefan Hajnoczi wrote:
>>> On Thu, Nov 03, 2011 at 10:35:28AM +0100, Fabien Chouteau wrote:
>>>> On 03/11/2011 08:44, Stefan Hajnoczi wrote:
>>>>> On Wed, Nov 2, 2011 at 5:39 PM, Fabien Chouteau <chouteau@adacore.com> wrote:
>>>>>> On 29/10/2011 15:52, Alexander Graf wrote:
>>>>> I took a quick peak at the qemu-trace.[ch] from couverture and it
>>>>> looks along the lines of the instrumentation that others have been
>>>>> doing too.  I hope you have time to propose the coverage
>>>>> instrumentation for upstream QEMU.
>>>>>
>>>>
>>>> I don't know much about other instrumentations in Qemu (pointers are
>>>> welcome :), but what we have in couverture-qemu is not trivial,
>>>> especially when it comes to MC/DC analysis. You should take a look at
>>>> 201005-erts2.pdf if you want technical details.
>>>
>>> My impression was that the QEMU portion of instrumentation was fairly
>>> simple - it writes out trace records at various interesting points
>>> during guest execution in TCG.
>>
>> It's not rocket science but for MC/DC you have to log history of
>> branches (taken or not), but if you record everything the output will
>> unreasonably grow.
>>
>>>
>>> I think fancy analysis scripts do not have to be part of QEMU but they
>>> could be added to scripts/ or put in a new contrib/ directory.
>>
>> What script are you talking about? GNATcoverage is far more complex than
>> a fancy script :)
>
> I'm not up to speed on GNATcoverage or couverture, so apologies if I'm
> wrong - please let me know.  Still, I think we're talking about the
> same thing here:
>
> http://www.adacore.com/home/products/gnatpro/add-on_technologies/gnatcoverage/
>
> Looks like GNATemulator is QEMU with additional instrumentation.
> GNATcoverage takes the execution traces that the instrumented QEMU
> produced.  So when I said "fancy analysis scripts", I meant the tool
> that analyzes the trace.
>

In your previous message you seemed to say that GNATcoverage could be
included in Qemu. I just wanted to explain that GNATcoverage is a
project on its own and will not be a part of Qemu.

>>> On the train, can't access the PDF you mentioned right now.
>>
>> Can't you checkout the repository?
>
> Sorry, I was reading/replying to mail offline.  I now grabbed the git
> repo and looked at commit b82469c906829865693b4fad0edb0a069604a8d9,
> which I believe is the main change needed to add couverture tracing to
> QEMU.

Right this is the main commit, there are few others to fix corner cases.

>
> I'm trying to see if you want to send QEMU changes upstream?

As I said it's in our plan, but we don't have time for now. You are
welcome to help if you want to.

-- 
Fabien Chouteau