Re: [Qemu-devel] git bisect results

[Erik Rull <erik.rull@rdsoftware.de>]

On January 30, 2012 at 2:48 PM Jan Kiszka <jan.kiszka@siemens.com> wrote:

> On 2012-01-30 14:17, Erik Rull wrote:
> >
> >
> >
> > On January 30, 2012 at 12:52 PM Jan Kiszka <jan.kiszka@siemens.com>
wrote:
> >
> >> On 2012-01-30 12:34, Erik Rull wrote:
> >>> Hi Jan,
> >>>
> >>> I'm sorry, but this does not solve my issue. I applied the patch and
> >>> crosschecked that the resulting file looks fine.
> >>>
> >>> The final function looks like:
> >>>
> >>> static void sdl_grab_start(void)
> >>> {
> >>> /*
> >>> * If the application is not active, do not try to enter grab state.
> > This
> >>> * prevents 'SDL_WM_GrabInput(SDL_GRAB_ON)' from blocking all the
> >>> * application (SDL bug).
> >>> */
> >>> if (!(SDL_GetAppState() & SDL_APPINPUTFOCUS)) {
> >>> return;
> >>> }
> >>> if (guest_cursor) {
> >>> SDL_SetCursor(guest_sprite);
> >>> if (!kbd_mouse_is_absolute() && !absolute_enabled)
> >>> SDL_WarpMouse(guest_x, guest_y);
> >>> } else
> >>> sdl_hide_cursor();
> >>> SDL_WM_GrabInput(SDL_GRAB_ON);
> >>> gui_grab = 1;
> >>> sdl_update_caption();
> >>> }
> >>
> >> That makes no sense as gui_grab must be 1 now. Please retry your
> >> previous instrumentation.
> >>
> >> Thanks,
> >> Jan
> >>
> >
> > You're right. So I added the instrumentation again.
> >
> > Still looks strange.
> >
> > So I added into the sdl_grab_start() a printf.
> > Wow - a lot of output!
> > This pointed me to all other sdl_grab_start() calls (and in additon to
that
> > all sdl_grab_end() calls).
> >
> > And here are the results of the qemu voting :-)
> >
> > I already assigned a usable name to the printf output that is directly
one
> > line above the corresponding sdl_grab_*() call, so you should be able
to
> > find this easily in your code as well.
> >
> > The huge number of recurring printf's are:
> >
> > sdl_grab_start() called from absolute_mouse_grab()
> > sdl_grab_end() called from handle_activation()
> > sdl_grab_start() called from absolute_mouse_grab()
> > sdl_grab_end() called from handle_activation()
> > sdl_grab_start() called from absolute_mouse_grab()
> > sdl_grab_end() called from handle_activation()
> > sdl_grab_start() called from absolute_mouse_grab()
> > sdl_grab_end() called from handle_activation()
> > sdl_grab_start() called from absolute_mouse_grab()
> > sdl_grab_end() called from handle_activation()
> > sdl_grab_start() called from absolute_mouse_grab()
> > sdl_grab_end() called from handle_activation()
> > sdl_grab_start() called from absolute_mouse_grab()
> > sdl_grab_end() called from handle_activation()
> >
> > Any idea how to proceed?
> >
> > Maybe the first two if-statements in handle_activation() cause the
problem?
> > Because there the two given functions are called in sequence if both
> > if-clauses are valid one after the other. Maybe the first one sets the
> > state so that the second if is valid, too. Maybe a simple else if
solves
> > the issue?
>
> ev->active.gain makes both clauses mutually exclusive - unless someone
> messes with the memory of the event object.
>
> > I'm not familiar with the variables that are checked here, so
> > it's just a guess.
>
> So handle_activation() is called directly after absolute_mouse_grab(),
> and the reported event contains
>
> state = SDL_APPINPUTFOCUS
> gain = 0
> (please validate!)
>
> That would mean we are constantly losing the input focus again after
> trying to gain it via SDL_WM_GrabInput. Weird.
>
> What's the call chain for absolute_mouse_grab()?
>
> Jan
>
> --
> Siemens AG, Corporate Technology, CT T DE IT 1
> Corporate Competence Center Embedded Linux


Here the results:

Handle Activation 0: at function start (before the first if)
Handle Activation 1: between the first and the second if
Handle Activation 2: after the second if

The output is formatted like:
printf("Handle Activation 0: %d %d %d %d\n",gui_grab,(ev->active.state ==
SDL_APPINPUTFOCUS),ev->active.gain,gui_fullscreen);

Handle Activation 0: 0 1 1 0
Handle Activation 1: 0 1 1 0
absolute_mouse_grab() called from handle_activation()
sdl_grab_start() called from absolute_mouse_grab()
Handle Activation 2: 1 1 1 0
Handle Activation 0: 1 1 0 0
sdl_grab_end() called from handle_activation()
Handle Activation 1: 0 1 0 0
Handle Activation 2: 0 1 0 0
Handle Activation 0: 0 1 1 0
Handle Activation 1: 0 1 1 0
absolute_mouse_grab() called from handle_activation()
sdl_grab_start() called from absolute_mouse_grab()
Handle Activation 2: 1 1 1 0
Handle Activation 0: 1 1 0 0
sdl_grab_end() called from handle_activation()
Handle Activation 1: 0 1 0 0
Handle Activation 2: 0 1 0 0
Handle Activation 0: 0 1 1 0
Handle Activation 1: 0 1 1 0
absolute_mouse_grab() called from handle_activation()
sdl_grab_start() called from absolute_mouse_grab()
Handle Activation 2: 1 1 1 0

The gain seems to toggle between the successive calls of
handle_activation...
Next steps?

Best regards,

Erik