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

[Stefan Hajnoczi]

On Fri, Nov 4, 2011 at 9:53 AM, Fabien Chouteau <address@hidden> 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 <address@hidden> 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.

>> 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.

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

Stefan