[BRLTTY] BRLTTY under real Dos

[Nicolas Pitre]

On Wed, 3 May 2006, Samuel Thibault wrote:

> Nicolas Pitre, le Wed 03 May 2006 12:28:58 -0400, a écrit :
> > Well... for such a use I'd probably investigate linking BRLTTY directly 
> > with grub instead.
> 
> That's quite another story, since grub doesn't provide all the features
> that an OS provides.  It doesn't handle interrupts, for instance.

Indeed, but BRLTTY shouldn't need much.  It needs a time abstraction for 
delays, plus some read() and write() replacements to communicate over 
the serial port, plus a memory allocator, and a grub specific screen 
driver.  Anything else can be stubbed out with dummy functions in 
sys_grub.c.

> Porting brltty to DOS would probably be much easier.

Are you sure?  I'm not, and I doubt there will be many users as well.
And that would be less useful and rather backward to me.  DOS is 
nevertheless a practically dead environment for which dosemu is 
certainly a good substitute in 99% of the cases.

> I already did some work on grub1: I added the VisioBraille driver
> to grub and added basic grub reading, and this already works quite
> fine.  But grub people don't accept any new features in grub1.  Such
> development would have to wait for grub2.

Of course I wouldn't envision adding BRLTTY to grub source base that 
would be insane and unmaintainable.  Instead there should be a way to 
add some kind of "plugins" capabilities to grub so BRLTTY configured for 
grub would only compile to a single grub_brltty.o file that the grub 
build process would be instructed to link with, and instanciated somehow 
at run time in a standard (non BRLTTY specific) way.

> More than that, it would be useful that brltty (and/or other screen
> readers) be able to provide basic drivers + basic screen reading engine
> as small independant objects.  That would even permit integration in
> BIOSes (even in proprietary BIOSes if the object licence permits it (BSD
> for instance, not GPL/LGPL))

I'm sorry to not be that inclined towards BSD licensing with BRLTTY 
code.  I've been in the disabled industry long enough to know that 
BRLTTY would then be quick to be used within proprietary products, which 
products readers of this list know for sure are completely 
closed and quite prohibitive.  Unless I have my share of the $$$ those 
companies charge for their products I'm not interested in changing the 
license for the code I wrote which includes the Alva driver and many 
parts of the core code.

Better encourage projects like LinuxBIOS and Grub where parts of BRLTTY 
may be used with no license issues and for the benefit of all instead.


Nicolas