linux-kernel - Re: [PATCH 0/2] fbdev: add fillrect and copyarea ioctls

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Message-ID: <20090714034353.GA1280@lilem.mirepesht>
Date:	Tue, 14 Jul 2009 08:13:53 +0430
From:	Ali Gholami Rudi <ali@...i.ir>
To:	Dave Airlie <airlied@...il.com>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	fbdev <linux-fbdev-devel@...ts.sourceforge.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andrea Righi <righi.andrea@...il.com>,
	Krzysztof Helt <krzysztof.h1@...pl>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Geert Uytterhoeven <Geert.Uytterhoeven@...ycom.com>,
	Philippe De Muyter <phdm@...qel.be>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] fbdev: add fillrect and copyarea ioctls

Dave Airlie <airlied@...il.com> wrote:
> On Tue, Jul 14, 2009 at 2:25 AM, Ali Gholami Rudi<ali@...i.ir> wrote:
> > Arjan van de Ven <arjan@...radead.org> 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
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