Re: [Qemu-discuss] [Qemu-devel] Questions about qemu enabling TCI (tcg/tci.c)

[Peter Maydell]

On 13 June 2018 at 15:10, yt zhang <address@hidden> wrote:
>  Dear technicians，
> Good day.
> I encountered some difficulties in learning about the TCI part of QEMU.
> When I use the following configuration command to enable TCI:
>
>          "configure --enable-tcg-interpreter"
>
> Run the command as:
>
>         "qemu-x86_64 hello-one" (hello-one is my own executable file).
>
> Then I counted the number of times TB was interpreted in the
> "tcg_qemu_tb_exec(CPUArchState *env, uint8_t *tb_ptr)" function in the
> tcg/tci.c file.However, I found that running the above command several
> times on the same host computer [Intel(R) Pentium(R) CPU G3250 @ 3.20GHz],
> the number of TB counts may sometimes be different (as shown below).

I think that's expected. We don't try to be purely deterministic
by default. You may find that suitable use of the -icount option
will give you more deterministic behaviour (though if your guest
program works with timers or signals or multiple threads it
will likely still not be deterministic.)

thanks
-- PMM