From: Andrew Apted <ajapted@netspace.net.au>
  To  : ggi-develop@eskimo.com
  Date: Thu, 19 Aug 1999 12:27:07 +1000

Re: VC Switching

Brian writes:

>  But, you have good arguments in favor of a sane vc-switching system.
>  They seem to reinforce the point that the graphics card needs
>  to be viewed as a resource server, serving up frames, sprites, 
>  textures, and whatnot, and not seen as a single resource; except for 
>  the actual focus (of which there is only one per monitor attached 
>  to the card, so those are single resources.)
>  
>  We should do the vc-switching system *right* even if it means
>  hacking it out entirely and putting it off for a while.
 
In my opinion, doing it *right* means not doing it in the kernel at
all.  A kernel should just be managing the devices (such as video
cards with whopping big memories), and allowing userspace to allocate,
deallocate & use the resources, but not implementing user interface
abstractions like VTs.

Imagine if an X server emulated the text consoles (and there's no
reason why it couldn't AFAIK).  It would be indistinguishable from the
current system.  I'm not advocating that BTW :->, but I think it
points the way to how it *should* be done.

And while I'm playing Devil's Advocate...  Ping Pong buffers.  I
understand how they work, but not _why_ to go to the extra trouble of
using page faults, instead of just calling some write() function which
can pass a big block of accel commands to the driver.  What is their
advantage ?

Cheers,
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  Andrew Apted   <ajapted@netspace.net.au>      \/