[BRLTTY] BRLTTY under real Dos

[Nicolas Pitre]

On Thu, 4 May 2006, Samuel Thibault wrote:

> Hi,
> 
> Nicolas Pitre, le Wed 03 May 2006 15:06:08 -0400, a écrit :
> > If you can do it in 32-bit mode I'd say just try it.  Otherwise I don't 
> > think it is worth the implied costs.
> 
> You can't know the real cost before beginning trying :)

Sure.  Go wild.  I won't.  ;-)

> On this issue, I really feel that adapting brltty to grub will probably
> be more invasive than adapting it to DOS. (yes, the potential benefit
> would be much broader though, so it would be worth the effort).

I still can't see how that can be so much more invasive.  Certainly not 
more than the 32 bits vs 16 bits issue.

> Well, anyway, this is just chatting, and makes us loose time instead of
> actually trying DOS port, discovering issues, probably realizing that
> they are too hard, and hence giving up (but at least it would have been
> tried).

I hate spending time on something just to give up afterwards.  This is 
why the chatting is useful as it makes you think twice before diving 
into new endeavors.

> > What operation can you do with DOS for booting Linux that you cannot do 
> > with Grub?
> 
> Having more powerful editing power than the simple grub editor.
> Saving parameters, copying files from a floppy/cdrom/whatever, ... The
> list is really long.

But those are conveniences.  Appreciable ones of course, but nothing 
that cannot be achieved from grub or Linux once booted I'd assume.

> But isn't a bad support in vendor BIOSes better than _no_ support?

I wonder.

> > Yet today's PCs are plain commodities which tag price has to be as low 
> > as possible.  Therefore I doubt BIOS vendors might be convinced into 
> > spending any resources for integrating such a feature that only 0.0001% 
> > of the total customer base might use.
> > <snip>
> > believing that can be achieved with vendor BIOSes is a peep dream
> > IMHO.
> 
> You find me quite optimistic about this, but IIRC, Janina told us
> at some time on a11y.org that she (or FSG, I can't remember) was
> contacted by some BIOS vendor about how they could make their BIOS
> accessible. For isntance, there's the Tiano project from Intel which can
> be an opportunity to take.

Interesting.

> I don't know if it can apply here, but remember that some US law enforce
> accessibility.

Oh of course.  And so far those laws appear to be satisfied when 
applications allow JFW to get to a textual description of various 
widgets on the screen.  At least this has been the state of affairs for 
a while.  So I think we're far, very far away from accessible BIOS 
concerns.

> > I'd hope for serial support from BIOSes before anything resembling 
> > native braille display support,
> 
> BIOSes _do_ already have serial support, since this is one of the
> services it provides to operating systems through interrupt 0x14.

I mean access to the BIOS setup interface over a serial port so you 
could operate with a second PC using a terminal emulator, not the actual 
BIOS call.  That ability is present on some server class machines that 
are expected to be headless but not with the average PC.

> > and yet this is a feature that doesn't work well even in the Grub
> > version installed with FC4!
> 
> Agreed.  Grub's built-in support for serial is quite poor, maybe because
> it doesn't use the uart IRQ.

I don't think that is the problem.  Reading characters typed over the 
serial port doesn't require that much.  It can be done with simple 
polling.  It's just what they do with those characters that appear 
to be broken.

> > Sorry to rain on your parade,
> 
> I'm a bit voiceless on this.  I don't even know how I should understand
> it...

"Désolé d'amoindrir ton enthousiasme."

> > > Do you really think LinuxBIOS will ever be usable on all PCs you can
> > > shop?
> > 
> > Certainly.  Motherboard manufacturers are using more and more "standard" 
> > chipsets increasing the likelihood for your PC to be supported by 
> > LinuxBIOS.
> 
> Agreed.  But will flashing your motherboard often be possible?  And how
> will you be able to do this by yourself if you don't have accessibility
> in the vendor BIOS?

Just like I'd need to do it if I needed a BIOS update to support my bran 
new braille display.


Nicolas