Subject: Re: "console" on multi-device busses
To: Erik E. Fair <>
From: Lennart Augustsson <>
List: tech-kern
Date: 05/16/1999 03:40:51
"Erik E. Fair" wrote:

> I honestly don't know which approach is better. UNIX has traditionally
> supported (where "support" means "get the hell out of the way") nearly
> completely "raw" access to various devices for applications that wanted it,
> but that means putting the smarts in the application. On the other hand, if
> the kernel virtualizes (as UNIX does for disks, TTYs, and other things with
> relatively well understood models of operation), then we take on the
> low-level support headaches. Are the Xfree86 people pushing any particular
> model for this?

I don't know what they have in mind.  Right now they use AT scancodes, which
the USB keyboards have to emulate anyway.  It's kind of yucky.

> I'm probably going to regret asking this, but is supporting a multiple
> console system (i.e. N frame buffers, with N keyboard/mouse combinations,
> for N users) so that multiple users can use one computer a really
> desireable thing?

I don't know if it is desirable, but I think it should be possible if you want
But that's not the case I worry about.  I worry about a single console with
multiple keyboards.  Like if you have a laptop and plug in an extra (USB)
keyboard.  These keyboard could (in Sweden) easily be of different types
and have different scancodes.
I would like this scenario to "just work".  And not just in X, but using play
ttys as well.

> Do you have a particular application in mind for your multiple-user
> multiple frame-buffer system?

As I said, that's not a scenario I worry too much about, but for those who
it I think it should be possible to do (the next version of XFree86 will
it better, I think).

I'm trying out my keyboard/mouse multiplexor stuff right now and I hope
to have a concrete suggestion soon on hiw to handle multiple input devices.


        -- Lennart