[maemo-developers] Wishlist (was:Re: N800 and USB host mode)

From: Daniel Amelang daniel.amelang at gmail.com
Date: Fri Mar 9 08:47:56 EET 2007
On 3/8/07, Daniel Stone <daniel.stone at nokia.com> wrote:
> On Thu, Mar 08, 2007 at 01:06:00PM -0800, ext Daniel Amelang wrote:
> > On 3/7/07, Eero Tamminen <eero.tamminen at nokia.com> wrote:
> > >Err.  Translucency means compositing and keeping the composited items in
> > >memory.  Due to additional memory accesses needed for this, it would be
> > >slower (and take more memory) regardless of how "accelerated" it would
> > >be.
> >
> > Keeping the composited items in memory is not necessary. After you
> > composite, you can (and often) just keep the final result around.
> The Composite extension to the X server requires a backing pixmap for
> every window, and a final pixmap which is essentially the fb.  So, while
> you're right about compositing as a concept, I think Eero's talking abou
> the possibility of using the Composite extension.


> > I don't totally agree here either. It sounds like you're saying that
> > the hardware acceleration won't get you much unless you have dedicated
> > video memory.
> He is, and I'm willing to back him up.

We must be talking about two different things, because you go on to
back me up below...

> > Here's a counter-example: the macbook uses an integrated graphics card
> > to do all of its fancy accelerated UI effects, including translucency.
> > Yes, the macbook is not a gaming machine, but that's not the issue,
> > here. The issue is that hardware-accelerated graphics enable advanced
> > user interfaces, even w/out dedicated video memory.
> It would be nice if we had the MacBook hardware in the N800's form
> factor, with the exact same power consumption.  Tragically, this is not
> the case, and our memory bandwidth is, shall we say, not staggeringly
> high, limited both by raw clock speed, and memory bus design.
> The MacBook has PCIE, and fast main memory, meaning that it's able to
> push textures between the GPU and main memory at a blazing fast rate.
> N800 has its own 'video memory' for the final framebuffer (so your main
> memory isn't impacted by the load of scanning out), but the rest would
> have to be done in main memory, where you're in direct contention with
> applications for the bandwidth.

Ah, we _are_ talking about two different things. I was making a point
that it is possible to make integrated graphics performant (which we
all seem to agree on, given everyone's comments on the MacBook).
You're saying that on the n800 specifically, it can't be performant
due to architecture limitations. I took Eero's comments to be directed
at integrated graphics in general, given his point about desktop

It is good to know what you have shared about the n800 hardware,
though. Which begs the question: where do you see the MBX being useful
to us (X, cairo, etc), given that it were available?


More information about the maemo-developers mailing list