[BRLTTY] linux screen driver and commands

[Yannick PLASSIARD]

On Fri, Mar 10, 2006 at 10:04:40AM +0100, Mario Lang wrote:
> Samuel Thibault <samuel.thibault at ens-lyon.org> writes:
> 
> > While working on Linux kernel facilities for speech-based screen
> > readers, I found an interesting possibility for driving brltty's speech
> > with the PC keyboard, without having to patch the Linux kernel:
> >
> > - open /dev/input/event0 (provided by the evdev module)
> > - call ioctl(fd, EVIOCGRAB, 1) on it: key presses stop being sent to the
> >   linux virtual console: instead,
> > - read(fd,buf,sizeof(struct input_event)) gets the key press event.
> >
> > This hence permits to grab key presses, which can then be used for
> > driving speech reading etc., while the usual key presses can be
> > simulated back via the uinput facility that we already implemented (the
> > simulated device will appear as another /dev/input/event1 evdev file).
> 
> Yes, I already suggested this plan to Dave in a private mail
> about a year ago or so.  It was especially interesting to some, since
> there are braille displays out there which do not have any display-local
> keys.  AFAICS, the only reason why it is not there yet is
> because no one implemented it.  ITs truly simple though, at least
> the key-forwarding part.
> 
> There is a problem though:  How do you figure out which
> keyboard to grab?  I use a USB keyboard at times, and my PS/2
> keyboard is still connected, so I definitely have two
> system-console keyboards.  Actually, three, since I
> use the Braille Star built-in PS/2 port, but that doesnt really
> count.
	We could simply grab all keys for all keyboards ? I never tried to put two keyboards on a computer. What happens ? Could we type at the same time on the two keyboards, or is there a "priority" or a "locking" facility to exclusively allow a keyboard to the linux console for example ?
> 
> > I will probably not work on this, but this should be enough material for
> > somebody to do it :)
> 
> Ahhh, dejavu ! :)
> 
> -- 
> CYa,
>   Mario
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