Re: asynchronous resolution change

["Jatin Kumar" <jatin.kumar@gatech.edu>]

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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
>

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