Re: [Qemu-devel] Monitor Memory Accesses

[Andrea Pellegrini <andrea.pellegrini@gmail.com>]

Thanks Laurent,
I slightly modified the code from Vince and it worked great for my 
purpose (at least to monitor the PC).
Just a quick question:
In the file linux-user/mmap.c, which is the difference between the two 
following lines? Does the first one provide the virtual address while 
the second one is already translated in the real address?

        p = mmap(g2h(mmap_start),
                 host_len, prot, flags | MAP_FIXED, fd, host_offset);

        p = mmap(real_start ? g2h(real_start) : NULL,
                 host_len, prot, flags, fd, host_offset);

I'm just starting to work on tracking the load/store. :-)

~Andrea

Laurent Desnogues wrote:
> On Wed, Feb 18, 2009 at 2:17 PM, Andrea Pellegrini
> <andrea.pellegrini@gmail.com> wrote:
>   
>> Thanks for the quick reply!
>>
>> I obtain the instruction addresses through the function
>> static TranslationBlock *tb_find_slow(target_ulong pc,
>>                                     target_ulong cs_base,
>>                                     uint64_t flags)
>>
>> ......
>> // Andrea, let's check the pc
>>   printf("PC: 0x%x\n", pc);
>> ....
>>
>> in cpu_exec.c. So far it worked but maybe there is a better way to do it.
>>     
>
> No, it doesn't work.  Try to track the PC of a loop and you'll see
> what I mean.
>
> You should start by learning what is run-time code generation ;)
>
>   
>> Where can I find more informations about the "helper"?
>> I'm just starting working with Qemu so I'm still not 100% sure about what is
>> going on.  :-P
>>     
>
> The documentation is the source.  It's not easy to enter, but once
> you've understood the basic inner-workings, doing what you're
> after should not be very difficult.
>
>   
>> I searched in target-i386/translate.c for
>> tcg_gen_qemu_ld
>> or
>> tcg_gen_qemu_lst
>> and nothing pops up. Am I looking at the right thing?
>>     
>
> I talked about tcg_gen_qemu_ld*.
>
> Just to make it clear, I am talking of svn version of qemu.  If you're
> using 0.9.1 then it's a completely different story, and I invite you to
> take a look at Vince Weaver's work:
>
> http://www.csl.cornell.edu/~vince/projects/qemusim/
> http://www.csl.cornell.edu/~vince/projects/qemu-trace/
>
>
> Laurent
>
>
>
>