Re: [Linux-fbdev-devel] [PATCH 0/2] fbdev: add fillrect and copyarea ioctls

[Ali G. R. <al...@ru...>]

Dave Airlie <ai...@gm...> wrote:
> On Tue, Jul 14, 2009 at 2:25 AM, Ali Gholami Rudi<al...@ru...> wrote:
> > Arjan van de Ven <ar...@in...> wrote:
> >> can we turn this around, is there a reason to add them?
> >> or in other words, how / where would these be used ?
> >
> > User-space programs that use framebuffer directly can use them.  I was
> > writing a simple framebuffer virtual terminal (using libfreetype for
> > fonts; like fbterm); scrolling and painting boxes would be faster if
> > there was someway of using hardware accelerated operations.  I think
> > other similar programs can benefit, too.
> 
> The general opinion is we should keep acceleration in userspace if at
> all possible.

I see.  The line between user- and kernel-space for graphic applications
is very blurred to me :-)

> Not all hw can implement these usefully in the kernel, directfb

AFAICT, many major ones like intelfb, radeonfb and nv implement them and
those that can't, use a software implementation.  You mean they are
unreliable or that there is little performance improvement because of
the way those operations are implemented in the kernel?

> already does some
> things for this.

Sometime ago I did try running directfb on a radeon r300 and it failed.
I didn't try hard to see what's wrong but I got the impression that
userspace apps are not good at using the hardware directly.

	Ali