From: James Simmons <jsimmons@edgeglobal.com>
  To  : ggi-develop <ggi-develop@eskimo.com>
  Date: Tue, 10 Aug 1999 15:26:29 -0400 (EDT)

Re: [linux-fbdev] newer patch. (fwd)

---------- Forwarded message ----------
Date: Tue, 10 Aug 1999 15:21:36 -0400
From: Jeff Garzik <jgarzik@pobox.com>
To: James Simmons <jsimmons@edgeglobal.com>
Subject: Re: [linux-fbdev] newer patch.

James Simmons wrote:
> > So you implement accel engine context switching?

> I would like to later on down the road. This isn't going to be easy.

No.  It would also be nice to have the _option_ of doing framebuffer
context switching.  You would have to do it to virtual memory, but it
should be possible.  Just very complex.  The new I/O structure in 2.3.x
should make this easier though.


> > Maybe I am just misunderstanding then.  So, much like /dev/fb presents
> > the frame buffer as an mmap-able memory area, /dev/gfx presents the MMIO
> > region as an mmap-able memory area?
> 
> Yes but /dev/gfx is more powerful than that. It can do things like mmap z
> buffers.

Nice.


> > Unfortunately Linus pretty much despises fbcon, even recently saying he
> > was glas most [x86] people don't use it.  So it will be tough to get a
> > proper virtualization into the kernel IMHO.
> 
> I get the feeling linus is just not a graphics guy. Eventually alot of
> drivers will be written. I know he will NOT accept /d3v/gfx but i don't
> care. Its for the public. I want people to use it so they can actually do
> the above.
> 
> As for performace I do have a idea to place virtualiziation into the
> kernel and have very little performace hits. Its called ping pong buffers.
> I will later explain later if you are interested.

Don't get me wrong, I fully support your work doing virtualization.  And
a quick explanation of your usage of ping pong buffers would be great,
if you have time.

I just want to make sure we don't start stuffing all the accel code into
the kernel...

Oh and another thing, if your /dev/fb and /dev/gfx work both make it
into the kernel, you could probably update KGICON and finally add that
to the kernel.

	Jeff





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