On Sat, Jul 4, 2015 at 1:06 AM, Peter Maydell <peter.mayd...@linaro.org> wrote:
> On 3 July 2015 at 18:02, Jun Koi <junkoi2...@gmail.com> wrote: > > I am looking at how the main thread interrupts TCG thread. Inside > > cpu-exec.c, in function cpu_tb_exec(), I can see that it executes one TB, > > and when this is over, it can check for events from other threads (like > main > > thread). This is the reason why TCG thread can be interrupted. > > > > Is my understanding correct? > > > > If this is true, then what if this TB is running infinitely, and do not > > return, or it is in a very long loop? In this case, TCG thread cannot be > > interrupted? > > Every TB starts with a little bit of generated code that checks > the 'tcg_exit_req' flag in the CPUState for the CPU (see the > gen_tb_start() function). If some other part of QEMU wants the > CPU to stop running guest code and return to the top level loop, > it calls cpu_exit() which sets this flag. > But this does not answer my question yet: if we the flag is only enable when TB already enters the "long loop", then nothing can break this TB execution? Thanks.
