[BRLTTY] BRLTTY under real Dos

[Samuel Thibault]

Hi,

Nicolas Pitre, le Wed 03 May 2006 23:23:32 -0400, a écrit :
> > 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.

On some archs, gcc has an option for turning ints into 32bits.  Maybe
such trick can be used here.

> > 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.

Ok, but a quick try (installing djgpp, trying to compile brltty, see the
issues) is not so long.  And probably shorter than our chatting.

> > > 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.

Grub cannot read cdroms, since for this it needs drivers (which haven't
been implemented so far, even in grub2).
Linux is another story of course :)

> > > 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.

Ok, I understand better your phrase now.  Well, if we provide braille
drivers, and why not a skeleton for very basic vga screen reading too,
the remaining work is very tiny, compared to implementing a serial
terminal support.

> > > 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.

I'm not sure Grub people actually _use_ that feature a lot.  Hence bugs.

> > > 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."

Ok, I understand this better :)

> > > > 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.

The vendor could provide such update.  Yeah, you can call me a dreamer
:)

By "flashing your motherboard", I was rather thinking "flashing your
motherboard with LinuxBIOS".  I.e. can LinuxBIOS images be used with any
board?  Doesn't flashing need special image formats?

Samuel