RE: [Linux-fbdev-devel] API prototype doc

[Geert U. <ge...@li...>]

On Tue, 4 Dec 2001, Sottek, Matthew J wrote:
> >>The only reason to not allow mmap is that it is hard to force apps
> >>to stop writing when they shouldn't.
> 
> >Why to stop them? If we do not provide full virtualization for them,
> >we should not put any additional policy on their behavior.
>  
> I'm ok with leaving out policy, but the problem is that we have no
> way to notify the client in a timely manner either. They would
> have to poll the surface to look at the status.
> 
> So what should be done on a vt switch?
> I think it may be ok to zap() someone's mmap during a vt switch but
> otherwise make them work out their own policy. vt switches are
> slow anyway.

That's why for 2.5.x we wanted to disable VT switching for a VT that has its
/dev/fb* opened by some application.

> I am unsure of how XFree handles this. Does the X server trap the
> vt switch sequence, call leave_vt() then switch the vt?

The X server indeed installs a VT switch handler, and releases access to the
hardware and does the VT switch.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@li...

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