Re: [Qemu-devel] Memory Traces for System Simulation

[Luis Useche <luis@cs.fiu.edu>]

On Thu, Jun 18, 2009 at 05:20:05PM +0200, Edgar E. Iglesias wrote:
> On Wed, Jun 17, 2009 at 05:50:18PM -0400, Luis Useche wrote:
> > Hi Guys,
> 
> Hello Luis,

Thanks for the response.

> > At the moment, I am instrumenting several functions in exec.c as my trace
> > points:
> > 	ldl_phys
> > 	ldq_phys
> > 	ldup_phys
> > 	lduw_phys
> > 	stl_phys_notdirty
> > 	stq_phys_notdirty
> > 	stl_phys
> > 	stb_phys
> > 	stw_phys
> > 	stq_phys
> 
> Depending on what you want to do and on your cache arch you might need
> to log both virtual and physical addresses. I don't know what the best
> place to hook in would be though.

If I can find the physical addresses that would be really great. And if I
can find both physical and virtual it would be even better. In any case, I
need to know what section of the code is the most likely to have this
memory operations to trace them.

> > I would really appreciate any suggestion you have in order to solve my
> > problem. If you have any insights in the solutions I explained above I
> > would be very thankful.
> > 
> > Given that many people seems to be having the same problem than I, it
> > would be nice to have an actual framework that add this functionality to
> > qemu. I can offer myself to do that as long as I have enough help.
> > 
> > As a parallel question: Does qemu simulate CPU cache? i.e. There is always
> 
> Nope.
> 
> > memory access even when this would not happen in a real system due to CPU
> > cache?
> 
> Yes correct.
> 
> I've got a pretty nasty hack that online emulates controller and tag
> memories. I find it useful for profiling and for some debugging. The data
> memories are not emulated so accesses are never absorbed. I don't think
> it's very useful for scientific purposes..
> 
> Anyway, it kind of works for CRIS and MicroBlaze. Feel free to look around
> on the cris git at your own risk :)
> git://repo.or.cz/qemu/cris-port.git

This can probably helps. Can you give me more information of what this
does.

Best,
-- 
Luis Useche <luis@cs.fiu.edu>
Ph.D. Student
Florida International University