Re: [Qemu-devel] memory trace with qemu

[Jun Koi]

On Mon, Jul 26, 2010 at 8:16 PM, malc <address@hidden> wrote:
> On Mon, 26 Jul 2010, Eliot Moss wrote:
>
>> On 7/26/2010 6:20 AM, Llu?s wrote:
>> > Eduardo Cruz writes:
>> >
>> > > Thanks for your awnsers. Stean, after I find the right place to capture
>> > > the
>> > > reads and writes I'll definitely try your trace tool.
>> >
>> > > Until now, this is what i found:
>> >
>> > > I am using the x86-64 target, and I know that, for instance, lots of 
>> > > reads
>> > > pass here:
>> >
>> > > target-i386/translate.c   gen_op_ld_T1_A0()
>> >
>> > Ok, I've seen at least 3 people working on this lately.
>> >
>> > Some time ago I wrote a message proposing two sets of modifications for
>> > qemu, in
>> > order to allow the analysis of guest code (like feeding traces to an
>> > architecture simulator).
>> >
>> > What I proposed is based on two different functionalities:
>> >
>> > 1) backdoor: a mechanism for the guest to communicate with qemu, such that
>> >     tracing can be started, stopped, etc.
>> >
>> >     My current approach is to decode an instruction that is deemed invalid
>> > by the
>> >     target ISA according to the manual.
>> >
>> >     This is only implemented for x86 right now, but it is trivial to
>> > implement on
>> >     other architectures as long as there are unused opcodes.
>> >
>> > 2) instrumentation: a set of generic macros that signal events that might 
>> > be
>> > of
>> >     interest.
>>
>> Etc.
>>
>> In the context of another simulator, we developed a different
>> technique, which would be quite general and might be of interest
>> for QEMU.  We communicate with the simulator via a "fake" *device*,
>> mapped into user-mode memory using an mmap call.  If someone
>> devised and coded such a device, then it could be used from any
>> guest.
>
> I'v done something similar a while ago:
> http://repo.or.cz/w/qemu/malc.git/shortlog/refs/heads/wctpci

in this repo tree, which part is your new code?

i looked at the git log, and tried to search your name, but none looks related.

thanks,
Jun