[BRLTTY] braille-kernel-image(s)

[Samuel Thibault]

Hi,

Indeed, the kernel itself could handle braille displays as a regular
console, hence providing for instance a 40x1 tty to applications. The
braille table could be chosen both at compile time, or as a kernel
parameter. But applications aren't ready for handling such a small
display.

What's more, keep in mind that many braille displays don't have any key
to type regular letters and such. So that the usual pc keyboard needs be
used for input. Then you also want to have program display their output
on the regular screen too, so as to show things to sighted people. You
hence need to have applications display things *both* on the screen and
on the braille display. The conventional unix tty structure doesn't
permit that.

What's more, braille devices really *can* be driven from userspace by
using /dev/ttyS*, just like printers are handled by cups, which just
uses /dev/lp*, so that kernel people will tell you "it can be done in
userspace, stay in userspace". And userspace is both much easier to
program and to release: having patches commited in the kernel might be
tedious, while having one's own repository is easier.

Now, one area where some kernel support would be useful is the startup.
We have discussed about it with Sebastien and we think that what could
be done is a bunch of very basic drivers and a very basic kernel
messages reader or even console reader. It could be used in grub too,
and even in Manufacturer BIOSes.

Regards,
Samuel