On Wed, Nov 19, 2008 at 3:35 AM, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
On Tue, 18 Nov 2008, Jatin Kumar wrote:
> I am new to linux fb model and had some queries regarding resolution change
> mechanisms.
>
> Consider a situation where the frambuffer kernel module (vfb/xenfb etc)
> wants to change the resolution.
>
> 1. Is there a mechanism to this, considering the applications/windowing
> system/console above the framebuffer hasnt initiated the size change?
>
> 2. Is there a way to do an upcall into the application/windowing
> system/console modules to inform them about the size change asynchronously?
>
> In this particular case ; the display hardware(instead of the user) has
> initiated the resolution change.Is it possible in the current fb framework
> to support it?

Yes there is! If the resolution is changed, and the number of columns and
lines of the console changes, the tty subsystem will send the SIGWINCH signal
to the application, cfr. tty_do_resize() in drivers/char/tty_io.c.

Note that not all applications handle it. E.g. X doesn't, AFAIK.

Gr{oetje,eeting}s,

                                               Geert

 
Hi Geert,

Thanks much for the info.

Is the tty_io_resize( ) relatively new? .
I am looking at 2.6.18.8 src code (used for xen) and could not find the function.

Also are there any plans for exposing a similar callback api in the linux fb model to make the applications stay updated about the underlying resolution/hardware mode changes?

Thanks so much,
Jatin
 


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                                           -- Linus Torvalds